Journal articles: 'Methylene (-CH2-) Group'

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Елена Михайловна, Чернова,, Орлов, Михаил Юрьевич, and Орлов, Юрий Димитриевич. "STUDY OF THE ELECTRONIC STRUCTURE OF B MOLECULES OF THE HOMOLOGOUS SERIES CH3(CH2)NC≡C(CH2)NCH3." Вестник Тверского государственного университета. Серия: Химия, no. 3(49) (October 28, 2022): 120–24. http://dx.doi.org/10.26456/vtchem2022.3.14.

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В рамках квантовой теории атомов в молекуле (QTAIM) рассчитаны характеристики электронной плотности в молекулах гомологического ряда CH(CH)C≡C(CH)CH. Установлено, что влияние группы C≡C распространяется на две ближайшие метиленовые группы. In the framework of the quantum theory of atoms in a molecule (QTAIM), the parameters of the electron density in molecules of the homologous series CH(CH)C≡C(CH)CH are compute. It was found that the influence of group C≡C extends to the two nearest methylene groups.

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Cowie, Martin. "2003 Alcan Award Lecture Roles of the adjacent metals in the coupling of methylene groups promoted by heterobinuclear complexes of Group 8 and 9 metals." Canadian Journal of Chemistry 83, no. 8 (2005): 1043–55. http://dx.doi.org/10.1139/v05-122.

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The reactivities of the heterobinuclear complexes, [MM′(CO)4(dppm)2][X] (MM′ = RhOs, RhRu, IrRu; dppm = µ-Ph2PCH2PPh2; X = BF4, CF3SO3) with diazomethane are reported. The RhOs species reacts to give three products of methylene-group incorporation, depending on the temperature; at 80 °C the methylene bridged product, [RhOs(CO)4(µ-CH2)(dppm)2][X], is formed exclusively, at ambient temperature only [RhOs(η1-C3H5)(CH3)(CO)3(dppm)2][X], having the allyl group bound to Rh and the methyl group bound to Os, is obtained, while at intermediate temperatures [RhOs(η1:η1-C4H8)(CO)3(dppm)2][X], having the butanediyl fragment chelating on Os, is generated. Based on labeling studies a mechanism is proposed rationalizing formation of the different products. Under the same range of conditions the Rh/Ru and Ir/Ru species yield only the methylene bridged products, [MM′(CO)4(µ-CH2)(dppm)2][X] (MM′ = RhRu, IrRu). A rationalization for the different reactivities observed and a description of the roles of the different metals in coupling of the methylene groups are presented. Attempts to model key intermediates in the methylene coupling sequence promoted by the Rh/Os complexes, through coupling of methylene groups with ethylene or alkynes, are described. Key words: heterobinuclear, rhodium/osmium, rhodium/ruthenium, iridium/ruthenium, methylene coupling, FischerTropsch, alkyne insertions, bimetallic cooperativity.

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Klopfenstein, Sean R., Constanze Kluwe, Kristin Kirschbaum та Julian A. Davies. "The reactions of [Pd2Cl2(μ-PP)2] (PP = dppm, dmpm) with Et2NC≡CNEt2 in methylene chloride solution: X-ray crystal structures of [Pd2Cl2(μ-CH2)(μ-dppm)2] and hexakis(diethylamino)benzene, C6(NEt2)6". Canadian Journal of Chemistry 74, № 11 (1996): 2331–39. http://dx.doi.org/10.1139/v96-260.

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The binuciear palladium(I) complex, [Pd2Cl2(μ-dppm)2] (dppm = bis(diphenylphosphino)methane), has been shown to react with bis(diethylamino)acetylene, Et2NC≡CNEt2, in methylene chloride solution to yield two isolable products, the known methylene-bridged complex, [Pd2Cl2(μ-CH2)(μ-dppm)2], and hexakis(diethylamino)benzene, C6(NEt2)6, both of which have been characterized crystallographically. The source of the bridging methylene group in [Pd2Cl2(μ-CH2)(μ-dppm)2] has been shown to be the methylene chloride solvent. A mechanism that accounts for the formation of the two isolable products is proposed. The complex, [Pd2Cl2(μdmpm)2] (dmpm = bis(dimethylphosphino)methane), was similarly found to react with Et2NC≡NEt2 in methylene chloride solution to yield [Pd2Cl2(μ-CH2)(μ-dmpm)2], which was identified spectroscopically. Key words: acetylene, palladium, cyclooligomerization, aminoacetylene, hexakis(diethylamino)benzene.

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Stevanovic, Jelena, Anton Rakitin, Ivan Kojic, Nikola Vukovic, and Ksenija Stojanovic. "Significance of infrared spectroscopic branching factor for investigation of structural characteristics of alkanes, geochemical properties and viscosity of oils." Journal of the Serbian Chemical Society 87, no. 1 (2022): 41–55. http://dx.doi.org/10.2298/jsc210830091s.

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A detailed investigation of significance of the infrared (IR) spectroscopic branching factor (??2/??3; the ratio of methylene and methyl group peak heights at 2917?2921 and 2951?2954 cm-1, respectively in the IR spectra) for characterization of alkane structure, geochemical properties and viscosity of 76 oil samples was performed. These oils, originating from 13 Serbian oil fields in SE Pannonian Basin, differ according to source and depositional environment of organic matter (OM), as well as by thermal maturity and biodegradation stage. Methylene and methyl asymmetric stretching peak absorbances were used for the branching factor calculation. CH2 peak positions exhibited 3?4 cm-1 red shift with increasing the CH2/CH3 ratio, due to a greater contribution of trans vs. gauche rotamers in aliphatic chains. Comparing IR spectra of the oils and model n-alkanes, it was established that the average (CH2)n methylene chain length per ??3 group varied from n = 3.5 to 6.5. The CH2/CH3 ratio showed significant concordance with geochemical parameters, enabling clear distinction of the oils according to source and depositional environment of OM. At the same time, dependence of the CH2/CH3 ratio on oil maturity in the range from immature to mature was not observed, allowing for an accurate determination of oil genetic types irrespective of maturity. The CH2/CH3 ratio showed good accordance with oil biodegradation scale and oil viscosity.

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Ramalingam, K., C. Rizzoli, G. S. Sivagurunathan, S. Sivasekar, T. Rajaraman, and M. Prabu. "Anhydrous Aluminum Chloride Catalyzed Methylene Group Inclusion: Mechanistic, Spectral and Single Crystal X-Ray Structural Study on Methanediyl Bis(Cyclohexylmethylcarbamodithioate)." International Letters of Chemistry, Physics and Astronomy 68 (July 2016): 61–70. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.68.61.

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In this study anhydrous AlCl3is used as a catalyst for the inclusion of a methylene group in to cyclohexylmethyldithiocarbamic acid to form methanediyl bis(cyclohexylmethylcarbamodithioate). Dichloromethane is used as a methylene group bearer in the reaction. A suitable mechanistic pathway involving+CH2Cl is discussed. FTIR, NMR and Mass spectral techniques have been used in the analysis. Single crystal X-ray structure of the compound was determined. FTIR spectrum of the compound showed υc-sband at 1073 cm-1and υC-Hvibrations appeared at 2853 and 2928 cm-1. Thioureide stretching band was observed at 1473 cm-1. The molecular ion peak in the Mass spectroscopy confirmed the proposed formula. H1NMR spectrum of the compound showed a signal at 4.33(s) ppm for α-CH of the cyclohexyl ring and -CH3protonsattached to nitrogen appeared at 3.40 ppm. Methylene proton (S-CH2-S) signal appeared at 3.16 ppm which is largely deshielded by the presence of two electronegative sulphur atoms on either side. The characteristic methylene carbon (S-CH2-S) signal appeared at 45.46 ppm in the13C NMR spectrum. Single crystal X-ray structural analysis of the compound showed it to be monomeric. Methylene carbon in S-CH2-S, C(9) is tetrahedrally bonded to two hydrogen atoms and two sulphur atoms S(2), S(3). The molecule stacks its cyclohexyl rings along ‘c’ axis of the unit cell. Short contacts in the form of supramolecular interactions such as C---S and S---S exist in the solid state at 3.49 and 3.50 Å respectively.

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Ramalingam, K., C. Rizzoli, G. S. Sivagurunathan, S. Sivasekar, T. Rajaraman, and M. Prabu. "Anhydrous Aluminum Chloride Catalyzed Methylene Group Inclusion: Mechanistic, Spectral and Single Crystal X-Ray Structural Study on Methanediyl Bis(Cyclohexylmethylcarbamodithioate)." International Letters of Chemistry, Physics and Astronomy 68 (July 19, 2016): 61–70. http://dx.doi.org/10.56431/p-f3pe87.

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In this study anhydrous AlCl3 is used as a catalyst for the inclusion of a methylene group in to cyclohexylmethyldithiocarbamic acid to form methanediyl bis(cyclohexylmethylcarbamodithioate). Dichloromethane is used as a methylene group bearer in the reaction. A suitable mechanistic pathway involving +CH2Cl is discussed. FTIR, NMR and Mass spectral techniques have been used in the analysis. Single crystal X-ray structure of the compound was determined. FTIR spectrum of the compound showed υc-s band at 1073 cm-1 and υC-H vibrations appeared at 2853 and 2928 cm-1. Thioureide stretching band was observed at 1473 cm-1. The molecular ion peak in the Mass spectroscopy confirmed the proposed formula. H1 NMR spectrum of the compound showed a signal at 4.33(s) ppm for α-CH of the cyclohexyl ring and -CH3 protonsattached to nitrogen appeared at 3.40 ppm. Methylene proton (S-CH2-S) signal appeared at 3.16 ppm which is largely deshielded by the presence of two electronegative sulphur atoms on either side. The characteristic methylene carbon (S-CH2-S) signal appeared at 45.46 ppm in the 13C NMR spectrum. Single crystal X-ray structural analysis of the compound showed it to be monomeric. Methylene carbon in S-CH2-S, C(9) is tetrahedrally bonded to two hydrogen atoms and two sulphur atoms S(2), S(3). The molecule stacks its cyclohexyl rings along ‘c’ axis of the unit cell. Short contacts in the form of supramolecular interactions such as C---S and S---S exist in the solid state at 3.49 and 3.50 Å respectively.

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7

Proulx, Grant, and Robert G. Bergman. "Reaction of a Tantalum Alkylidene Complex with Dinuclear Metal Carbonyls: Formation of C3 ligands." Science 259, no. 5095 (1993): 661–63. http://dx.doi.org/10.1126/science.259.5095.661.

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The mechanisms of reactions that deoxygenate carbon monoxide (CO) and convert it into longer chain hydrocarbons are not well understood. A series of reactions between "early" and "late" transition metal complexes that result in CO coupling reactions in a homogeneous solution are reported. In one example, the Schrock tantalum-methylene complex (η5-C5H2)2Ta(CH2)(CH3) reacts with the dinuclear metal carbonyls CO2(CO)8 and Fe2(CO)9 in a novel fashion to yield a C3H2O2 ligand bridging three metal centers. Reaction of the tantalum-methylene complex with Re2(CO)10 leads to an even more substantial change in which extensive rearrangement along with three-carbon coupling occurs. An oxygen atom is removed from one CO group, leading to the novel oxotantalum compound (η5-C5H5)2(CH3)Ta=O. Simultaneously, the carbon atom from the transformed CO couples with two CH2 groups initially bound to tantalum and the CH2 hydrogens are rearranged to produce a CH3-CC ligand. Low-temperature nuclear magnetic resonance and isotope tracer experiments have provided preliminary information about the mechanisms of these unusual carbon-carbon bond-forming reactions.

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Sedenkova, Kseniya N., Kristian S. Andriasov, Tamara S. Kuznetsova, and Elena B. Averina. "Oxyfunctionalization of CH2-Group Activated by Adjacent Three-Membered Ring." Current Organic Synthesis 15, no. 4 (2018): 515–32. http://dx.doi.org/10.2174/1570179415666180405113158.

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Background: Increasing use of the three-membered ring in drug development initiates the search for efficient methods of transformations of cyclopropane derivatives. Oxidation of methylene group activated by an adjacent cyclopropane represents a direct approach towards carbonylcyclopropanes, allows avoiding unnecessary synthetic stages and meets the requirements of atom economy. Objective: In this review all available data concerning the oxidation of cyclopropane-containing hydrocarbons and their functionally substituted derivatives are systematized, and the general regularities between the structure of the starting compound, the oxidant employed and the reaction outcome are underlined. Conclusion: The following regularities were distinguished for the oxidation of cyclopropane-containing compounds into cyclopropylketones. The main structural parameters of the starting compounds, which influence the distribution of the oxidation products, are the followings: the presence of competing C-H bonds, flexibility or rigidity of structure, electron and sterical substituents effects. A number of preparative methods of activated C(sp3)-H bonds oxygenation were elaborated, employing such powerful oxidants as ozone, dioxiranes, CrO3 and a variety of catalytic systems, based on transition metals. For the oxidation of cyclopropane derivatives all these oxidants may be employed. RuO4, generated in situ, usually behaves as selective and soft oxidant. TFDO often demonstrates lesser selectivity, but it may be the best choice when several activated CH2 groups should be oxidised. In the case of dihalocyclopropanes the use of CrO3 is preferable. Summarily, the oxidation of methylene group adjacent to cyclopropane has been undoubtedly developed into a reliable preparative approach to cyclopropylketones, which should find an active use in synthetic organic chemistry.

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Mazumdar, Pooja Anjali, Amit Kumar Das, Valerio Bertolasi, Sandip Kumar Kundu, and Animesh Pramanik. "A Folded Conformation around the Methylene Group in Simple Boc–NH–(CH2)3–NH–Boc: An X-ray Diffraction Study." Journal of Chemical Research 2002, no. 12 (2002): 640–41. http://dx.doi.org/10.3184/030823402103171104.

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Structural studies on model compounds Boc–NH–(CH2)2–NH–Boc (1) and Boc–NH–(CH2)3–NH–Boc (2) have shown the inherent tendency of the propylene group to adopt a folded conformation, which may help in peptide and peptide nucleic acid (PNA) design.

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Wang, Zhi-Qiang, Harry Adams, Neil A. Bailey, Michael L. Turner та Peter M. Maitlis. "The syntheses and structures of the phenyl-di-μ-methylene-dirhodium complexes, [{(η5-C5Me5)Rh(μ-CH2)}2(Ph)(Br)] and [{(η5-C5Me5)Rh(μ-CH2)}2(Ph)2]". Canadian Journal of Chemistry 73, № 7 (1995): 1206–12. http://dx.doi.org/10.1139/v95-148.

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Reaction of PhMgBr with [{(η5-C5Me5)Rh(μ-CH2)2(Br)2] in a halide-specific reaction gave, first, the monophenyl complex 2a [{(η5-C5Me5)Rh(μ-CH2)}2(Ph)(Br)] and then the diphenyl complex 3[{(η5-C5Me5)Rh(μ-CH2)}2(Ph)2]. X-ray crystal structure determinations showed both molecules to have trans structures, [{(η5-C5Me5)Rh(μ-CH2)}2(Ph)(Br)] (a = 10.066(3), b = 11.065(3), c = 14.002(3) Å; α = 85.23(2)°, β = 70.10(2)°, γ = 65.22(2)°; U = 1328.2(6) Å3; Z = 2; space group [Formula: see text] final R, 0.0586) and [{(C5Me5)Rh(μ-CH2)}2(Ph)2] (a = 17.102(8), b = 10.396(4), c = 16.134(7) Å; U = 2869(2) Å3; Z = 4; spacegroup Pccn [Formula: see text] No. 56), final R = 0.0426). Keywords: X-ray structure determination, pentamethylcyclopentadienyl, di-μ-methylene, rhodium

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11

Dagys, Laurynas, Barbara Ripka, Markus Leutzsch, et al. "Geminal parahydrogen-induced polarization: accumulating long-lived singlet order on methylene proton pairs." Magnetic Resonance 1, no. 2 (2020): 175–86. http://dx.doi.org/10.5194/mr-1-175-2020.

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Abstract. In the majority of hydrogenative parahydrogen-induced polarization (PHIP) experiments, the hydrogen molecule undergoes pairwise cis addition to an unsaturated precursor to occupy vicinal positions on the product molecule. However, some ruthenium-based hydrogenation catalysts induce geminal hydrogenation, leading to a reaction product in which the two hydrogen atoms are transferred to the same carbon centre, forming a methylene (CH2) group. The singlet order of parahydrogen is substantially retained over the geminal hydrogenation reaction, giving rise to a singlet-hyperpolarized CH2 group. Although the T1 relaxation times of the methylene protons are often short, the singlet order has a long lifetime, provided that singlet–triplet mixing is suppressed, either by chemical equivalence of the protons or by applying a resonant radiofrequency field. The long lifetime of the singlet order enables the accumulation of hyperpolarization during the slow hydrogenation reaction. We introduce a kinetic model for the behaviour of the observed hyperpolarized signals, including both the chemical kinetics and the spin dynamics of the reacting molecules. Our work demonstrates the feasibility of producing singlet-hyperpolarized methylene moieties by parahydrogen-induced polarization. This potentially extends the range of molecular agents which may be generated in a hyperpolarized state by chemical reactions of parahydrogen.

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Parra, Rubén D. "Hydrogen-Bond-Driven Peptide Nanotube Formation: A DFT Study." Molecules 28, no. 17 (2023): 6217. http://dx.doi.org/10.3390/molecules28176217.

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DFT calculations were carried out to examine geometries and binding energies of H-bond-driven peptide nanotubes. A bolaamphiphile molecule, consisting of two N-α amido glycylglycine head groups linked by either one CH2 group or seven CH2 groups, is used as a building block for nanotube self-assembly. In addition to hydrogen bonds between adjacent carboxy or amide groups, nanotube formation is also driven by weak C-H· · ·O hydrogen bonds between a methylene group and the carboxy OH group, and between a methylene group and an amide O=C group. The intratubular O-H· · ·O=C hydrogen bonds account for approximately a third of the binding energies. Binding energies calculated with the wB97XD/DGDZVP method show that the hydrocarbon chains play a stabilizing role in nanotube self-assembly. The shortest nanotube has the length of a single monomer and a diameter than increases with the number of monomers. Lengthening of the tubular structure occurs through intertubular O-H· · ·O=C hydrogen bonds. The average intertubular O-H· · ·O=C hydrogen bond binding energy is estimated to change with the size of the nanotubes, decreasing slightly towards some plateau value near 15 kcal/mol according to the wB97XD/DGDZVP method.

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Mijin, Dusan, and Dusan Antonovic. "Temperature dependence of the Kovats retention indices for alkyl 1, 3-diketones on a DB-5 capillary column." Journal of the Serbian Chemical Society 69, no. 10 (2004): 759–67. http://dx.doi.org/10.2298/jsc0410759m.

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A series of alkyl 1,3-diketones were used to study the temperature dependence of the Kovats retention indices in the temperature range 130?190 ?C (403?463 K). The temperature dependence is described by the empirical equation I = B B/T + ClnT. On the basis of this equation, the activation enthalpy, ?H?, and the chemical potential of the partitioning of one methylene group between the two phases of the chromatographic system, ??p(CH2), were calculated. Also the Kovats retention indices ? boiling point correlations (linear and reciprocal) for alkyl 1,3-diketones were studied and ??p(CH2) was calculated.

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Fatoni, Ahmad, Poedji Loekitowati Hariani, Hermansyah Hermansyah, and Aldes Lesbani. "Synthesis and Characterization of Chitosan Linked by Methylene Bridge and Schiff Base of 4,4-Diaminodiphenyl Ether-Vanillin." Indonesian Journal of Chemistry 18, no. 1 (2018): 92. http://dx.doi.org/10.22146/ijc.25866.

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The synthesis chitosan-methylene bridge-Schiff base of 4,4-diaminodiphenyl ether-vanillin using casting method has been done. The aims of this research were modification chitosan with Schiff base of 4,4-diaminodiphenyl ether-vanillin, formaldehyde and its characterization using FTIR spectroscopy, SEM analysis, 1H-NMR and X-Ray Diffraction analysis. The first step was a synthesis of modified chitosan between chitosan and Schiff base of 4,4-diaminodiphenyl ether-vanillin. The second step was chitosan modified Schiff base of 4,4-diaminodiphenyl ether-vanillin then reacted with formaldehyde through casting method. The result showed that chitosan can be modified with Schiff base of 4,4-diaminodiphenyl ether-vanillin and formaldehyde and this modified chitosan can be linked by methylene bridge (-NH-CH2-NH-) and had azomethine group (-C=N-). The functional group of –C=N in modified chitosan before and after adding formaldehyde appeared at a constant wavenumber of 1597 cm-1. The functional group C-N in methylene bridge detected at 1388 and 1496 cm-1. The chitosan-Schiff base of 4,4-diaminodiphenyl ether-vanillin and Chitosan-methylene bridge-Schiff base of 4,4-diaminodiphenyl ether-vanillin had index crystalline (%)16.04 and 25.76, respectively. The chemical sift of signal proton azomethine group (-C=N-) in modified chitosan detected at 8.44–8.48 and 9.77 ppm. Proton from methylene bridge in modified chitosan appeared at 4.97–4.99 and 3.75 ppm. Surface morphology chitosan-methylene bridge-Schiff base of 4,4-diaminodiphenylether-vanillin had dense surfaces, mostly uniform and regular in shape.

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Chudgar, N. K., and Alpana Shah. "Synthesis and study of mesogenic compounds having a methylene ketone (-CH2-CO-) linking group." Liquid Crystals 14, no. 4 (1993): 1163–67. http://dx.doi.org/10.1080/02678299308027824.

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Butcher, Ray J., та Andrew P. Purdy. "μ-Methylene-bis[dibromido(diethyl ether-κO)aluminium(III)]: crystal structure and chemical exchange in solution". Acta Crystallographica Section E Crystallographic Communications 77, № 6 (2021): 647–52. http://dx.doi.org/10.1107/s2056989021005302.

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In the title compound, [Al2Br4(CH2)(C4H10O)2], the molecule lies on a crystallographic twofold axis passing through the bridging C atom. Each AlIII atom is four-coordinate, being bonded to two bromide ions, bridging the CH2 group as well as the oxygen atom of a diethyl ether ligand in a slightly distorted tetrahedral arrangement with angles ranging from 101.52 (8) to 116.44 (5)°. The Al—CH2—Al angle, 118.4 (2)°, is the smallest observed for a structure where this moiety is not part of a ring. In the crystal, weak C—H...Br interactions, characterized as R 2 2(12) rings, link the molecules into ribbons in the [101] direction. The title compound is monomeric and coordinatively saturated in the solid state, as each aluminum is four-coordinate, but in solution the ether molecules from either or both Al atoms can dissociate, and would be expected to rapidly exchange, and this is supported by NMR data.

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Lübbe, W., A. Franken, and W. Preetz. "Darstellung, 11B-, 13C-, 1H-NMR- und Schwingungsspektren von 1.2-Trimethylenpentahydro-closo-Hexaborat(1 - ) , cis - [B6H5(CH2)3]- und 1.2-Tetramethylenpentahydro-closo-Hexaborat(1-), cis-[B6H5(CH2)4]- sowie Kristallstrukturen von [P(C6H5)4][B6H5(CH2)3] und [P(C6H5)4][B6H5(CH2)4] / Preparation, 11B, 13C, 1H NMR and Vibrational Spectra of 1.2-Trim ethylenepentahydro-closo-hexaborate(1-), cis-[B6H5(CH2)3]-, and 1.2-Tetramethylenepentahydro-closo-hexaborate(1-), cis-[B6H5(CH2)4]-, and the Crystal Structures of [P(C6H5)4][B6H5(CH2)3] and [P(C6H5)4][B6H5(CH2)4]." Zeitschrift für Naturforschung B 49, no. 8 (1994): 1115–22. http://dx.doi.org/10.1515/znb-1994-0816.

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By reaction of [B6H6]2- with diiodopropane or diiodobutane in dichloromethane the 1,2- rimethylene-pentahydro-closo-hexaborate(1-), cis-[B6H5(CH2)3]-, and the 1,2-tetra-methylene- entahydro-closo-hexaborate(1-), dv-[B6H5(CH2)4]- are obtained, respectively. The compounds were separated from excess [B6H6]2- by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structures of [P(C6H5)4][B6H5(CH2)3] (I) and [P(C6H5)4][B6H3(CH2)4] (II) have been determined by single crystal X-ray diffraction analysis: I is triclinic, space group P1̅ with a = 7,388(2), b = 12,254(2), c = 14,415(2) Å, α = 85,638(12)°, β= 84,06(2)°, γ = 85,13(2)°; II is monoclinic, space group P21/c with a =9,7855(10), b = 11,0793(10), c = 25,2386(10) Å, β= 2,491(10)°. The 11B NMR spectra of oth compounds reveal the feature of a cis-disubstituted octahedral B6 cage. The 13C NMR pectrum of I exhibits a quartet at 15,46 ppm with 1J(C,B) = 121,7 Hz (B-CH2) and a triplet at 37,98 ppm with 1J(C,H) = 124,4 Hz (CH2). For II a quartet at 12,89 ppm with 1J(C,B) = 105,5 Hz (B-CH2) and a triplet at 30,00 ppm with 1J(C,H) = 124,4 Hz (CH2) are observed. In the 1H NMR spectrum of I two multiplets at 0,73 and 1,90 ppm of the CH2 groups and two singlets at 2,23 and -3,71 ppm of the BH fragments are bserved; the signals of the CH2 groups of II are at 0,60 and 1,35 ppm and of the BH fragments at 2,15 and -4,81pm,respectively. The IR and Raman spectra exhibit five very strong CH stretching bands between 2807 and 2938 cm-1 in case of I and between 2817 and 2889 cm 1 in case of II.

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Andrade, L. C. R., J. A. Paixão, M. J. M. de Almeida, E. J. Tavares da Silva, and F. M. Fernandes Roleira. "N-Hexyl-3-(4-hydroxy-3,5-dimethoxyphenyl)propanamide." Acta Crystallographica Section E Structure Reports Online 68, no. 6 (2012): o1603—o1604. http://dx.doi.org/10.1107/s1600536812019022.

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In the title compound, C17H27NO4, which is an hydrosinapic acid derivative with increased lipophilicity conferred by an additional alkyl chain, the central and the hexyl linear chains contain slightly shorter bond lengths [C—N = 1.316 (2) Å; average linear chain C—C = 1.487 (6) Å] than reported average values [Csp 2—N = 1.334, C—C for CH2—CH2 = 1.524 and 1.513 Å for CH2—CH3]. The 4-hydroxy-3,5-dimethoxyphenyl plane [r.m.s. deviation 0.055 (12) Å] makes an angle of 59.89 (5)° with the central plane of the molecule (composed of the N atom, the carbonyl group and the two methylene C atoms linking the carbonyl group and the ring, [r.m.s. deviation 0.0026 (10) Å], which, in turn, makes an angle of 64.24 (13)° with the essentially planar hexyl chain [r.m.s. deviation 0.035 (18) Å]. The N—H group of the amide group is involved in a bifurcated hydrogen bond towards the hydroxy and one of the methoxy O atoms of the 4-hydroxy-3,5-dimethoxyphenyl substituent of a neighbouring molecule, forming a two-dimensional network in the (100) plane. In addition, the same hydroxy group acts as a donor towards the carbonyl O atom of another neighbouring molecule, forming chains running along the b axis.

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Djordjevic, Bratislav, Oliver Schuster, and Hubert Schmidbaur. "Auration of the Sulfones MeSO2CH2CN and CH2(CH2SO2)2CH2." Zeitschrift für Naturforschung B 60, no. 2 (2005): 169–74. http://dx.doi.org/10.1515/znb-2005-0207.

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MeSO2CH2CN shows considerable C-H acidity at its methylene group. Through lithiation followed by reaction with (Ph3P)AuCl it can therefore be readily converted into the dinuclear, geminally substituted product MeSO2C[Au(PPh3)]2CN. With an excess of aurating reagents, a third [(Ph3P)Au] group becomes N-bonded to the nitrile unit to give an ionic trinuclear compound {MeSO2C[Au(PPh3)]2CNAu(PPh3)}+BF4−. The same product is obtained by direct reaction of MeSO2CH2CN with [(Ph3P)Au]BF4. The crystal structures of the two products have been determined. The diaurated sulfone parts of the molecule and the cation are virtually superimposible. Small Au-C-Au angles and short Au-Au contacts suggest significant aurophilic interactions (“Aframe” structures). The small -C≡N-Au angle of 165.6(5)° in the cation indicates that the strong [(Ph3P)Au]+ acceptor causes substantial changes in the bonding of the nitrile group. Dilithiation of 1,3-dithiane-S,S’-tetroxide followed by reaction with 2 equivalents of (Ph3P)AuCl affords the geminally diaurated compound CH2(CH2SO2)2C[Au(PPh3)]2.

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20

Lübbe, W., та W. Preetz. "Darstellung, 11B-, 13C-, 1H-NMR- und Schwingungsspektren von μ-Methylen-bis-hexahydro-closo-hexaborat, [B6H6(CH2)B6H6]2-, und Kristallstruktur von [As(C6H5)4]2[B6H6(CH2)B6H6]· ½(CH3)2CO / Preparation, 11B- , 13C-, 1H NMR and Vibrational Spectra of μ-Methylene-bis-hexahydro-doso-hexaborate, [B6H6(CH2)B6H6]2- and Crystal Structure of [As(C6H5)4]2[B6H6(CH2)B6H6]· ½(CH3)2CO". Zeitschrift für Naturforschung B 51, № 4 (1996): 545–50. http://dx.doi.org/10.1515/znb-1996-0418.

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Abstract By reaction of [B6H6]2- with dibromomethane in acetonitrile μ-Methylene-bis-hexahydro-closo-hexaborate, [B6H6(CH2)B6H6]2-, is formed which can be separated from excess [B6H6]2- by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structure of [As(C6H5)4]2[B6H6(C H2)B6H6] · (CH3)2CO has been determined by single crystal X-ray analysis: triclinic, space group P1 with a = 10.779(2), b = 10.8003(12) and c = 23.077(3) Å, a = 99.147(10), β = 91.569(13) and y = 91.288(11)°. The 11B NMR spectrum reveals the features of a monosubstituted octahedral B6 cage. The 13C NMR spectrum exhibits a multiplet at -5.44 ppm. In the 1H NM R spectrum a singlet of the methylene protons at 0.23 ppm and two singlets at 1.97 and -4.52 ppm of the BH fragments are observed. The IR and Raman spectra exhibit strong CH stretching bands between 2873 and 2762 cm-1, BH stretching bands between 2443 and 2403 cm-1, and a BC stretching vibration at 1138 cm-1 in the Raman spectrum.

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21

Achmad, M. Janib, Ardan Samman, and Nebuchadnezzar Akbar. "Action of Ergost-7-en-3- ol from (Acanthaster planci) stimulation of activity peritoneal macrophages." Pharmacia 71 (April 25, 2024): 1–9. http://dx.doi.org/10.3897/pharmacia.71.e113504.

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An is a compound capable of influencing the human immune system because it can maintain and restore the balance of the immune system by stimulating the immune system through phagocytosis, the complement system, IgA antibody secretion, the release of interferon α and γ, T and B lymphocytes, specific antibody systems, and cytokines. Immunomodulators can be obtained from natural sources, one of which is Acanthaster planci, which is one of the marine organisms that has important bioactive substances that can act as immunomodulators. The purpose of this research is to determine the immunomodulatory activity of chloroform fractions FrKl3.1.3.1 and FrKl3.1.3.2 and to identify the immunomodulatory compounds from the chloroform fraction FrKl3.1.3.1 of A. planci. The results of the study showed that the macrophage test of the FrKl3.1.3.1 fraction had higher activity compared to FrKl3.1.3.2, while the spectroscopic data analysis results showed that UV-VIS had a maximum absorption at a wavelength (λmax) of 240 nm, FTIR data (cm-1) showed the presence of hydroxyl (-OH) groups, alkene groups (double bonds (C=C)), and aliphatic C-H groups. The 1H-NMR data (CDCl3, 500 MHz) showed six methane groups, ten aliphatic methylene groups (-CH2-), nine geminal methylene groups, one methylene group with a double bond, and 13C-NMR and DEPT 135 data (CDCl3, 125 MHz) indicated that the A. planci FrKl3.1.3.1 fraction had 28 carbon atoms consisting of six methyl (-CH3) carbon atoms, ten methylene (-CH2) carbon atoms, and nine methine (-CH-) carbon atoms. From the spectroscopic analysis data, it is known that the chloroform fraction of A. planci FrKl3.1.3.1 is ergost-7-en-3-ol compound.

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22

Achmad, M. Janib, Ardan Samman, and Nebuchadnezzar Akbar. "Action of Ergost-7-en-3- ol from (Acanthaster planci) stimulation of activity peritoneal macrophages." Pharmacia 71 (April 25, 2024): 1–9. https://doi.org/10.3897/pharmacia.71.e113504.

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An is a compound capable of influencing the human immune system because it can maintain and restore the balance of the immune system by stimulating the immune system through phagocytosis, the complement system, IgA antibody secretion, the release of interferon α and γ, T and B lymphocytes, specific antibody systems, and cytokines. Immunomodulators can be obtained from natural sources, one of which is Acanthaster planci, which is one of the marine organisms that has important bioactive substances that can act as immunomodulators. The purpose of this research is to determine the immunomodulatory activity of chloroform fractions FrKl3.1.3.1 and FrKl3.1.3.2 and to identify the immunomodulatory compounds from the chloroform fraction FrKl3.1.3.1 of A. planci. The results of the study showed that the macrophage test of the FrKl3.1.3.1 fraction had higher activity compared to FrKl3.1.3.2, while the spectroscopic data analysis results showed that UV-VIS had a maximum absorption at a wavelength (λmax) of 240 nm, FTIR data (cm-1) showed the presence of hydroxyl (-OH) groups, alkene groups (double bonds (C=C)), and aliphatic C-H groups. The 1H-NMR data (CDCl3, 500 MHz) showed six methane groups, ten aliphatic methylene groups (-CH2-), nine geminal methylene groups, one methylene group with a double bond, and 13C-NMR and DEPT 135 data (CDCl3, 125 MHz) indicated that the A. planci FrKl3.1.3.1 fraction had 28 carbon atoms consisting of six methyl (-CH3) carbon atoms, ten methylene (-CH2) carbon atoms, and nine methine (-CH-) carbon atoms. From the spectroscopic analysis data, it is known that the chloroform fraction of A. planci FrKl3.1.3.1 is ergost-7-en-3-ol compound.

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23

Gruwel, Marco L. H., and Roderick E. Wasylishen. "Molecular Motion in Phenpropylammonium Chloride Studied by Deuterium NMR." Zeitschrift für Naturforschung A 47, no. 10 (1992): 1073–86. http://dx.doi.org/10.1515/zna-1992-1012.

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AbstractCation dynamics in phenpropylammonium chloride, C6H5(CH2)3NH3Cr, were studied in three different solid phases by means of 2H nmr. Both 2H nmr line shapes and spin-lattice relaxation studies were performed on the ammonium head group, the adjacent methylene group and the phenyl-ring. In the low temperature phase, solid III, the - ND3 group dynamics were dominated by C3 jumps about the C - N axis. From the observed minima in T1Z and T1Q a quadrupole coupling constant of 165 ± 5 kHz was obtained. The 2H nmr line shapes of the methylene group indicate that this group does not execute any large amplitude motion in the low temperature phase. In contrast, the phenyl ring deuterium nuclei give rise to line shapes characteristic of C2 ring flips about the Cpara - Cipso axis.In the solid II phase the 2H nmr line shapes of both the - ND3 and - CD2 - groups are characterized by asymmetric Pake powder patterns. Since one of the principal components of the electric field gradient tensor remains temperature independent for both groups, it was concluded that these groups perform planar large-amplitude motions between two sites. Axially symmetric spectra were obtained for all three groups in the high temperature phase, solid I. The 2H nmr line shapes indicate the presence of whole ion reorientation about a molecular axis. In addition, the - ND3 groups perform C3 jumps about the C - N axis and the - C6D5 group display line shapes characteristic for rotational diffusion about the Cpara - Cipso axis.

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24

Delgado, Gerzon E., Lis E. Fernández, Angelina C. Coronel, and Eduardo L. Varetti. "X-ray powder diffraction data for methylene bis(thiocyanate) CH2(SCN)2, a microbicide for water-treatment purposes." Powder Diffraction 30, no. 1 (2014): 79–81. http://dx.doi.org/10.1017/s0885715614001122.

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X-ray powder diffraction data, unit-cell parameters, and space group for methylene bis(thiocyanate) (C3H2N2S2) are reported [a = 6.6888(4) Å, b = 8.0616(6) Å, c = 11.089(1) Å, β = 105.33(1), Z = 4, unit-cell volume V = 576.68(7) Å3, with M20 = 56.0 and F30 = 43.8 (0.0079, 87)]. All measured lines were indexed and are consistent with the monoclinic I2/c space group.

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25

Poletaeva, Olga Yu, Alexandr Yu Leontev, Eldar M. Movsumzade, Galina Yu Kolchina, and Elbay R. Babayev. "STUDY OF COMPOSITION OF HIGH-VISCOUS HEAVY OILS BY METHOD OF NUCLEAR MAGNETIC RESONANT SPECTROSCOPY." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 64, no. 1 (2020): 52–58. http://dx.doi.org/10.6060/ivkkt.20216401.6261.

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The work uses the nuclear magnetic resonance method to study the composition of heavy high-viscosity oils of various fields of the Volga Ural oil and gas basin. The spectra were recorded on a Bruker Avance III 500MHz high resolution NMR spectrometer with operating frequencies of 1H (500.1 MHz) and 13C (125.8 MHz) at a constant sample temperature in CDCl3. It is established that the oil of the studied field in its physical and chemical characteristics, structural group composition of resins, asphaltenes and oil components is a typical representative of aromatic oils. Oil samples are characterized by high density, a high content of tar-asphaltene compounds and sulfur. In the 1H NMR scale, methylene and methine signals appear in the range from 1.0 to 2.3 ppm: β-CH2, some β-CH groups in aromatic compounds and β-CH, CH2-groups in hydroaromatic compounds, and in the 13C NMR scale they are in the range from 22 to 60 ppm: methylene group (CH2-) in naphthenic fragments, etc. An analysis of the aromaticity coefficients obtained from the 1H and 13C NMR spectra shows a high convergence of the results and indicates a high degree of aromatic condensation in oil samples with a density of 950 kg/m3, a viscosity of 7200 mPa*s at 20 °C and a density of 948 kg/m3, viscosity 1000 mPa·s (FHA=0.046-0.081). With an increase in viscosity, there is a clear tendency to increase the aromaticity coefficient and the average chain length. It follows from the results of the 1H NMR spectra of oils with different origins, viscosities and processing that crude and refined oils may differ in water and olefin signals, and from 13C NMR analysis for oils the most important results were obtained when assessing the concentration of primary, tertiary and aromatic carbon.

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26

Poletaeva, Olga Yu, Alexandr Yu Leontev, Eldar M. Movsumzade, Galina Yu Kolchina, and Elbay R. Babayev. "STUDY OF COMPOSITION OF HIGH-VISCOUS HEAVY OILS BY METHOD OF NUCLEAR MAGNETIC RESONANT SPECTROSCOPY." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 64, no. 1 (2020): 52–58. http://dx.doi.org/10.6060/ivkkt.20216401.6261.

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The work uses the nuclear magnetic resonance method to study the composition of heavy high-viscosity oils of various fields of the Volga Ural oil and gas basin. The spectra were recorded on a Bruker Avance III 500MHz high resolution NMR spectrometer with operating frequencies of 1H (500.1 MHz) and 13C (125.8 MHz) at a constant sample temperature in CDCl3. It is established that the oil of the studied field in its physical and chemical characteristics, structural group composition of resins, asphaltenes and oil components is a typical representative of aromatic oils. Oil samples are characterized by high density, a high content of tar-asphaltene compounds and sulfur. In the 1H NMR scale, methylene and methine signals appear in the range from 1.0 to 2.3 ppm: β-CH2, some β-CH groups in aromatic compounds and β-CH, CH2-groups in hydroaromatic compounds, and in the 13C NMR scale they are in the range from 22 to 60 ppm: methylene group (CH2-) in naphthenic fragments, etc. An analysis of the aromaticity coefficients obtained from the 1H and 13C NMR spectra shows a high convergence of the results and indicates a high degree of aromatic condensation in oil samples with a density of 950 kg/m3, a viscosity of 7200 mPa*s at 20 °C and a density of 948 kg/m3, viscosity 1000 mPa·s (FHA=0.046-0.081). With an increase in viscosity, there is a clear tendency to increase the aromaticity coefficient and the average chain length. It follows from the results of the 1H NMR spectra of oils with different origins, viscosities and processing that crude and refined oils may differ in water and olefin signals, and from 13C NMR analysis for oils the most important results were obtained when assessing the concentration of primary, tertiary and aromatic carbon.

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27

Mihajlovic-Lalic, Ljiljana, Aleksandar Savic, Gabrijela Bradjan, Tibor Sabo, and Sanja Grguric-Sipka. "Novel methylene bridged ethylenediamine-type ligands: Synthesis and spectral characterization." Journal of the Serbian Chemical Society 79, no. 10 (2014): 1199–204. http://dx.doi.org/10.2298/jsc140212042m.

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Herein we report the synthesis of two new organic compounds, diisobutyl- and diisopentyl N,N?-methylene-(S,S)-ethylenediamine-N,N?-di-2-(3-cyclohexyl)propanoate. A one-pot procedure was carried out by adding the reducing agent and carbonyl compound into the methanol solution of the parent compounds (iso-butyl and iso-pentyl esters of (S,S)-ethylenediamine-N,N?-di-2-(3-cyclohexyl)propanoic acid) in appropriate stoichiometric ratios. The compounds were fully characterized by infrared, ESI-MS, 1D (1H, 13C) and 2D (COSY, HSQC, HMBC) NMR spectroscopy and elemental analysis. The spectral data confirm the presence of -CH2- group introduced between nitrogen atoms of the ethylenediamine moiety revealing neutral form of potential bidentate ligand.

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28

Castro, Mirian R. C. de, Angelo Q. Aragão, Hamilton B. Napolitano, Caridad Noda-Perez, and Felipe T. Martins. "An additional methylene group driving the conformation and assembly of two arylsulfonamidepara-alkoxychalcone hybrids." Acta Crystallographica Section C Crystal Structure Communications 69, no. 3 (2013): 267–72. http://dx.doi.org/10.1107/s0108270113002291.

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The structures of two arylsulfonamidepara-alkoxychalcones, namely,N-{4-[(E)-3-(4-methoxyphenyl)prop-2-enoyl]phenyl}benzenesulfonamide, C22H19NO4S, (I), andN-{4-[(E)-3-(4-ethoxyphenyl)prop-2-enoyl]phenyl}benzenesulfonamide, C23H21NO4S, (II), reveal the effect of the inclusion of one –CH2– group between the CH3branch and the alkoxy O atom on the conformation and crystal structure. Although the molecular conformations and one-dimensional chain motifs are the same in both structures, their crystallographic symmetry, number of independent molecules and crystal packing are different. The crystal packing of (I) is stabilized by weak C—H...π and π–π interactions, while only C—H...π contacts occur in the structure of (II). The role of the additional methylene group in the crystal packing can also be seen in the fact that the alkoxy O atom is an acceptor in nonclassical hydrogen bonds only in thepara-ethoxy analogue, (II). The remarkable similarity between the crystal packing features of (I) and (II) lies in the formation of N—H...O hydrogen-bonded ribbons, a synthon commonly found in related compounds.

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29

Bender, Desiree N., Alan J. Lough, R. Stephen Wylie, Robert A. Gossage та Daniel A. Foucher. "Preparation and DFT Studies of κ2C,N-Hypercoordinated Oxazoline Organotins: Monomer Constructs for Stable Polystannanes". Inorganics 8, № 5 (2020): 35. http://dx.doi.org/10.3390/inorganics8050035.

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Tetraorganotin tin(IV) compounds containing a flexible or rigid (4: Ph3Sn-CH2-C6H4-R; 7: Ph3SnC6H4-R, R = 2-oxazolinyl) chelating oxazoline functionality were prepared in good yields by the reaction of lithiated oxazolines and Ph3SnCl. Reaction of 7 with excess HCl resulted in the isolation of the tin monochlorido compound, 9 (ClSn[Ph2]C6H4-R). Conversion of the triphenylstannanes 7 and 4 into their corresponding dibromido species was successfully achieved from the reaction with Br2 to yield 10 (Br2Sn[Ph]C6H4-R) and 11 (Br2Sn[Ph]-CH2-C6H4-R), respectively. X-ray crystallography of 4, 7, 9, 10, and 11 reveal that all structures adopt a distorted trigonal bipyramidal geometry around Sn in the solid state. Compound 4, with an additional methylene spacer group, displays a comparatively long Sn–N bond distance compared to the dibromido tin species, 11. Several DFT methods were compared for accuracy in predicting the solid-state geometries of compounds 4, 7, 9–11. Compounds 10 and 11 were further converted into the corresponding dihydrides (12: H2Sn[Ph]C6H4-R, 13: H2Sn[Ph]-CH2-C6H4-R), via Br–H exchange, in high yield by reaction with NaBH4. Polymerization of 12 or 13 with a late transition metal catalyst produced a low molecular weight polystannane (14: –[Sn[Ph]C6H4-R]n–, Mw = 10,100 Da) and oligostannane (15: –[Sn[Ph]-CH2-C6H4-R]n–, Mw = 3200 Da), respectively.

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30

Mathur, Pradeep, Bala Manimaran, Md Munkir Hossain, C. V. V. Satyanarayana, Vedavati G. Puranik та Sudam S. Tavale. "Insertion of methylene group into FeTe bond: synthesis and characterization of {(CO)3Fe(μ-CH2)Te}2". Journal of Organometallic Chemistry 493, № 1-2 (1995): 251–55. http://dx.doi.org/10.1016/0022-328x(94)05353-d.

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31

Suganuma, Yuta, and Yuichi Kobayashi. "Formation of COOH-Ylides, and Their Reactivities and Selectivities in Wittig Reactions." Synlett 30, no. 03 (2019): 333–37. http://dx.doi.org/10.1055/s-0037-1611958.

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Whereas two equivalents of base are typically required to prepare carboxylate (CO2 –) ylides [Ph3P+C–(H)-alk-CO2 –] (alk = alkanediyl) from carboxy (CO2H) phosphonium salts [(Ph3PCH2-alk-CO2H)+] X–, we reveal, for the first time, that carboxy ylides [Ph3P+C–(H)-alk-CO2H] can be generated with one equivalent of NaHMDS at 0 °C, and that the Wittig reaction of simple aliphatic aldehydes (1 equiv) with these carboxy ylides (1.5–2 equiv) in THF at –95 to –90 °C for one hour, then at warming temperatures to 0 °C over two hours affords (Z)-alkenoic acids. Phosphonium salts containing (CH2) n alkanediyl chains (n = 2–5) showed adequate reactivity and high Z-selectivity, whereas shorter or longer alkanediyl chains resulted in a low Z-selectivity and/or a low yield. On the basis of these results with different (CH2) n chains and that obtained with a rigid methylene group, we propose that a rapid equilibrium between Ph3PCH 2-alk-CO2 – and Ph3P+C–(H)-alk-CO2 H, through an intramolecular hydrogen exchange, accounts for the success of the Wittig reaction.

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32

David, Shantha, David Dolphin, Brian R. James, et al. "Synthesis and characterization of durene-capped porphyrins and the crystal structure of a hemin derivative." Canadian Journal of Chemistry 64, no. 1 (1986): 208–12. http://dx.doi.org/10.1139/v86-036.

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Sterically hindered porphyrins having a fully hydrophobic cavity have been prepared. The cavity is capped with a 2,3,5,6-tetramethylbenzene moiety containing at the 1,4-positions methylene —(CH2)n— chains (n = 4, 5, 7) bonded at trans pyrrole rings of a porphyrin that is alkylated with methyl or ethyl groups at the other β-pyrrolic positions. The iron(III) chloride derivative of the 4,4-durene-capped base has been obtained as single crystals, and subjected to X-ray structural analysis. The typical high spin, square pyramidal geometry of five-coordinate hemin chlorides is maintained; the porphyrin core is strongly distorted and there is no interaction between the phenyl group of the strap and the iron.

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33

Fornika, Roland, Christian Six, Helmar Görls, Magnus Kessler, Carl Krüger, and Walter Leitner. "Synthesis and structural features of complexes [(P∩P)2Rh][hfacac] containing hexafluoroacetyl- acetonate as a noncoordinating anion." Canadian Journal of Chemistry 79, no. 5-6 (2001): 642–48. http://dx.doi.org/10.1139/v01-039.

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The synthesis and characterization of complexes [(P∩P)2Rh][hfacac] (P∩P = chelating bidentate phosphine ligand R2P(CH2)nPR2 (2a-g), hfacac = hexafluoroacetylacetonate anion) (4) is reported. The molecular structures of 4a (R = Ph, n = 1) and 4f (R = Cy, n = 2) in the solid state were determined by single-crystal X-ray diffraction. The complexes crystallize in the monoclinic space groups C2/c (No. 15) and P21/n (No. 14), respectively. No coordinative interaction between the rhodium center of the cation [(P∩P)2Rh]+ (4a+, 4f+) and the hfacac anion is evident in either cases. In the crystal structure of 4a, hydrogen bonds between the oxygen atoms of the hfacac anion and methylene protons of the CH2 bridges of the phosphine ligand lead to highly symmetric chains of regularly alternating cations and anions. The coordination geometry around the rhodium center in 4a+ is ideally square-planar, whereas 4f+ is significantly distorted towards a tetrahedron with an angle between the two P2Rh moieties of 18.6°. The cation 4b+ (R = Cy, n = 1) was investigated in form of the tetrafluoroborate salt for comparison. The compound [{Cy2P(CH2)PCy2}2Rh][BF4] crystallizes as a THF solvate (4b′) in the triclinic space group P[Formula: see text] (No. 2) containing ideally square-planar [(P∩P)2Rh]+ cations. Key words: rhodium, chelating ligands, coordination modes, 1,3-diketonates, phosphorus ligands.

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34

Teltayev, B., and T. Seilkhanov. "NMR-Spectroscopy Determination of Fragmentary Composition of Bitumen and its Components." Eurasian Chemico-Technological Journal 20, no. 2 (2018): 153. http://dx.doi.org/10.18321/ectj696.

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This paper represents and discusses the results of quantitative determination for fragmentary composition of road bitumen of grade BND 100/130 and its components (asphaltenes, resins and oils) by NMR spectroscopy method. Group chemical composition of the bitumen has been determined by adsorption chromatography method. It has been identified that the bitumen and its components consist only of aromatic and aliphatic protons, which account for 2.4‒10.2% and 9.8‒97.6% respectively. Availability of olefinic elements in them has not been identified. The most part (79‒81%) of nuclei of carbon atoms relates to quaternary carbon atoms of saturated compounds. Primary carbon atoms at methylene group (CH2) are contained in the least quantity: bitumen ‒ 1.32%; asphaltenes – 0.6%; resins – 3.24% and oils – 2.11%. Primary carbon atoms, linked with CH-group or aromatic nucleus, occupy an intermediate position and are contained in the quantity of 17‒20%.

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Kidonakis, Marios, та Manolis Stratakis. "Reduction of the Diazo Functionality of α-Diazocarbonyl Compounds into a Methylene Group by NH3BH3 or NaBH4 Catalyzed by Au Nanoparticles". Nanomaterials 11, № 1 (2021): 248. http://dx.doi.org/10.3390/nano11010248.

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Supported Au nanoparticles on TiO2 (1 mol%) are capable of catalyzing the reduction of the carbene-like diazo functionality of α-diazocarbonyl compounds into a methylene group [C=(N2) → CH2] by NH3BH3 or NaBH4 in methanol as solvent. The Au-catalyzed reduction that occurs within a few minutes at room temperature formally requires one hydride equivalent (B-H) and one proton that originates from the protic solvent. This pathway is in contrast to the Pt/CeO2-catalyzed reaction of α-diazocarbonyl compounds with NH3BH3 in methanol, which leads to the corresponding hydrazones instead. Under our stoichiometric Au-catalyzed reaction conditions, the ketone-type carbonyls remain intact, which is in contrast to the uncatalyzed conditions where they are selectively reduced by the boron hydride reagent. It is proposed that the transformation occurs via the formation of chemisorbed carbenes on Au nanoparticles, having proximally activated the boron hydride reagent. This protocol is the first general example of catalytic transfer hydrogenation of the carbene-like α -ketodiazo functionality.

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Zhong, Xiao Xing, Guo Lan Dou, Hai Hui Xin, and De Ming Wang. "Study on Low-Temperature Oxidation Process of Low Rank Coal by In Situ FTIR." Advanced Materials Research 652-654 (January 2013): 871–76. http://dx.doi.org/10.4028/www.scientific.net/amr.652-654.871.

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Low temperature oxidation of two different low rank coals was measured by in-situ FTIR. Curve-fitting analysis was employed to identify functional groups types of raw coals, and series technology was carried out on in-situ infrared spectrum of sample coals at low-temperature oxidation process to analyze the changes of main active functional groups with temperature. The results indicate that -CH3, -CH2, -OH, C=O, COOH are the main active functional groups in low rank coal. In the oxidation process, with temperature increasing, the methyl and methylene show the tendency of increase after decrease and then decrease, and all of hydroxyl, carboxyl and carbonyl group present the tendency of increase after decrease, there exists some differences among the main functional groups in the coal low-temperature process.

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37

Šubrtová, Věra, Václav Petříček, and Karel Malý. "The crystal structure of o-(1,2-dicarba-closo-dodecaborane-1-yl)methyl-cholesterol." Collection of Czechoslovak Chemical Communications 56, no. 10 (1991): 1983–92. http://dx.doi.org/10.1135/cccc19911983.

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The structure of C2B10H11.CH2C27H45O was determined by X-ray diffraction. This compound crystallizes in the orthorhombic system with the P212121 space group. The unit cell parameters are a = 994.0(4), b = 3 231.0(7), c = 1 039.6(2) pm, V = 3 338 . 106 pm3, Z = 4, calculated density Dc = 1.080Mg m-3. Mr = 542.9, linear absorption coefficient μ(MoK α) = 0.54 cm-1 F(000) = 1 184. Intensities were measured at room temperature, radiation used λ(MoK α) = 71.073 pm. Final R = 0.063 for 2 099 observed independent reflections. The studied molecule is built from ortho-carborane icosahedron connected with the cholesterol through the methylene CH2 group bonded to the icosahedral carbon atom C(B1) (C-C= 151.0(7) pm) and to the oxygen atom of the cholesterol (C-O = 138.3(7) pm). Valence angle C(B1)-C-O = 108(2)°, torsion angle C(B1)-C-O-C(3) = 164(4)°.

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38

J, Mancini-Filho. "Bioavailability and Functionality of Conjugated Fatty Acids in Foods." Bioequivalence & Bioavailability International Journal 6, no. 1 (2022): 1–3. http://dx.doi.org/10.23880/beba-16000167.

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Dietary conjugated fatty acids are associated with heart disease, obesity, diabetes, cancer and others; in addition, many functions of cell membranes are dependent on lipid composition and lipids ingested through the diet can modify this composition and their biochemical activity. Due to the discoveries of their chemical and physiological properties, there is a growing interest in conjugated fatty acids as well as in the properties of their isomers. Conjugated fatty acids (CFAs) are the general term to describe the positional and geometric isomers of polyunsaturated fatty acids with conjugated double bonds, which are separated by a single carbon-carbon bond rather than being separated by a methylene group (CH2). Theoretically, several isomers of conjugated fatty acids are possible, with multiple combinations of numerical, positional and geometric configurations of the conjugation of double bonds, which may present as conjugated linoleic and α-linolenic acids and may have different functionalities in the body.

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39

Sonoyama, Masashi, Kunihiro Shoda, Gen Katagiri, and Hideyuki Ishida. "Dynamic Step-Scan Two-Dimensional Fourier Transform Infrared Studies of Uniaxially Drawn Poly(Ethylene Terephthalate) Film." Applied Spectroscopy 50, no. 3 (1996): 377–81. http://dx.doi.org/10.1366/0003702963906249.

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Dynamic infrared spectra of uniaxially drawn poly(ethylene terephthalate) (PET) under a sinusoidal strain were examined. A very intense dynamic band at 973 cm−1 assigned to the trans C-O stretching mode indicated stress-induced high mobility around the C-O bond in the ethylene glycol units. It was supposed that derivative-like skeletal bands observed in the dynamic spectra originated from the stress-induced frequency shift. Two-dimensional correlation analyses of the dynamic spectra were also carried out and revealed that the phenyl ring 18a band at 1018 cm−1 and the phenyl ring 19b band at 1410 cm−1 were composed of three and two independent components, respectively. The correlation peaks between the phenyl ring and CH2 vibrational modes showed that orientation of the methylene group in the ethylene glycol unit, induced by mechanical stretching, is faster than that of the phenyl ring in the terephthalate unit.

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40

Schaefer, Ted, Kerry J. Cox, Cherrie L. Morier, Christian Beaulieu, Rudy Sebastian, and Glenn H. Penner. "Motion about the bond in benzyl OR (R = CH3, CH2CH3, CH(CH3)2, C(CH3)3). Solvent and substituent dependence." Canadian Journal of Chemistry 68, no. 9 (1990): 1553–58. http://dx.doi.org/10.1139/v90-240.

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The 1H nuclear magnetic resonance spectral parameters of benzyl alkyl ethers (CH3, CH2CH3, CH(CH3)2, and C(CH3)3) in CS2 and acetone-d6 solutions are obtained, as are those for the 3,5-dichloro derivatives (CH3, CH2CH3, and CH(CH3)3) in acetone-d6 solution. The long-range coupling constants between the methylene and para ring protons show that the apparent twofold barrier to rotation about the [Formula: see text] bond is solvent and ring-substituent dependent. The apparent twofold barrier ranges from a vanishing value for benzyl methyl ether in CS2 solution to as much as 4.6 kJ/mol for 3,5-dichlorobenzyl isopropyl ether in acetone-d6 solution. The data imply that, for the free molecules, the conformation of highest energy has the CH2—O bond in a plane perpendicular to that of the phenyl group. Molecular orbital computations with a minimal Gaussian basis set agree that, for benzyl methyl ether in the exo form (the methyl group pointing away from the phenyl moiety), this conformation is the least stable. However, geometry optimization procedures imply that the CH2—O bond is twisted out of the ring plane by 30.3° in the most stable geometry of the exo form. Such procedures for the (distorted) endo form locate another stable conformer, in which the CH2—O bond is twisted out of the phenyl plane by 45°, only 0.25 kJ/mol less stable than the most stable conformer of the exo form. These results, together with some computations for the tert-butyl derivative, are discussed in terms of the theoretical potentials for rotation about the [Formula: see text] bond. The approximate potential surface is rather flat compared to kT at ambient temperatures for the free molecules, consistent with its sensitivity to the medium and to ring substituents. Keywords: 1H NMR, benzyl alkyl ethers; long-range coupling constants in benzyl alkyl ethers; conformations, benzyl alkyl ethers; internal motion, benzyl alkyl ethers; MO computations on benzyl methyl ether.

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41

Ibrahim, Saraa Muwafaq, and Ziad T. Abd Ali. "Using of modified-bentonite as low-cost sorbent for removal of methylene blue dye from aqueous solution." Association of Arab Universities Journal of Engineering Sciences 27, no. 2 (2020): 45–54. http://dx.doi.org/10.33261/jaaru.2020.27.2.005.

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Batch experiments have been studied to remove methylene blue dye (MB) from aqueous solution using modified bentonite. The modified bentonite was synthesized by replacing exchangeable calcium cations in natural bentonite with cationic surfactant cetyl trimethyl ammonium bromide (CTAB). The characteristics of modified bentonite were studied using different analysis such as Scanning electronic microscopy (SEM), Fourier transform infrared spectrometry (FTIR) and surface area. Where SEM shows the natural bentonite has a porous structure, a rough and uneven appearance with scattered and different block structure sizes, while the modified bentonite surface morphology was smooth and supplemented by a limited number of holes. On other hand, (FTIR) analysis that proved NH group aliphatic and aromatic group of MB and silanol group are responsible for the sorption of contaminate. The organic matter peaks at 2848 and 2930 cm-1 in the spectra of modified bentonite which are sharper than those of the natural bentonite were assigned to the CH2 scissor vibration band and the symmetrical CH3 stretching absorption band, respectively, also the 2930 cm-1 peak is assigned to CH stretching band. The batch study was provided the maximum removal efficiency (99.99 % MB) with a sorption capacity of 129.87 mg/g at specified conditions (100 mg/L, 25℃, pH 11 and 250rpm). The sorption isotherm data fitted well with the Freundlich isotherm model. The kinetic studies were revealed that the sorption follows a pseudo-second-order kinetic model which indicates chemisorption between sorbent and sorbate molecules.

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42

Maharajh, Rabindranath B., James P. Snyder, James F. Britten, and Russell A. Bell. "Synthesis, high-field NMR, X-ray structure, and conformational analysis of a 10-membered diamide disulfide ring." Canadian Journal of Chemistry 75, no. 2 (1997): 140–61. http://dx.doi.org/10.1139/v97-018.

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N,N′-[Dimethyl-(2,2′-dithiobisacetyl)]ethylenediamine (1) has been synthesized in 30% overall yield from N,N′-dimethylethylenediamine and thioacetic acid by an improved procedure involving simultaneous deprotection and oxidative cyclization with iodine. This cyclic diamide disulfide exists in solution as a mixture of two Z,Z and one Z,E disulfide, and amide ring conformers and has been characterized by nuclear Overhauser effect (NOE), 1H–1H, 1H–13C shift-correlated 2D-NMR and molecular modelling studies. Among the Z,Z ring conformers Z,Z1 and Z,Z2, the former predominates and interconverts with the latter isomer by rotation about the S—S bond with an activation energy of 14.5 ± 1.3 kcal/mol. Coalescence of N-CH3 signals occurred at ca. 127 °C (500 MHz), which corresponded to an approximate barrier to amide rotation of 19.3 kcal/mol. Aromatic solvent-induced shifts in C6D6 corroborated molecular mechanics and NOE predictions of amide stereochemistry. The structure of the Z,E stereoisomer of 1 has been determined by single-crystal X-ray diffraction at 296 K. A large geminal N-CH2 inequivalence (>2 ppm in CDCl3) was observed for the Z,Z conformers. Proton chemical shifts have been calculated for the conformers of 1 and related molecular fragments with DFT/GIAO theory. Absolute chemical shifts are modelled within 0.2 ppm of experiment. The unusual nonequivalence of geminal N-CH2 and S-CH2 protons can be understood as a combination of shielding mechanisms derived from short N-methyl contacts, amide group orientation, and sulfur lone-pair disposition. An implication of these results is the possibility of using α-CH (and eventually α-CH) shifts to probe the local conformational space in cyclic peptides and other conformationally constrained rings. Keywords: amide/disulfide rotamers, conformational analysis, density functional theory, DFT/GIAO NMR shift calculations, methylene nonequivalence, molecular modelling.

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43

Cauzzi, Daniele, Claudia Graiff, Maurizio Lanfranchi, Giovanni Predieri, and Antonio Tiripicchio. "Copper-promoted intramolecular selenium transfer from a PSe group to a P–CH2–P methylene carbon producing an unusual methaneselone ligand." J. Chem. Soc., Chem. Commun., no. 23 (1995): 2443–44. http://dx.doi.org/10.1039/c39950002443.

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44

Selvianti, Selvianti, Mohammad Wijaya, and Maryono Maryono. "Identifikasi Senyawa Patkouli Alkohol dari Minyak Atsiri Daun Nilam (Pogostemon cablin benth.) Identification Of Patchouli Alcohol Compounds from The Essential Oil Of Patchouli Leaves (Pogostemon cablin benth.)." Chemica: Jurnal Ilmiah Kimia dan Pendidikan Kimia 25, no. 2 (2024): 41. https://doi.org/10.35580/chemica.v25i2.54035.

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Penelitian ini bertujuan untuk mengetahui banyaknya kandungan senyawa patkouli alkohol yang terdapat dalam minyak atsiri daun nilam dan karakteristik senyawa patkouli alkohol yang terdapat dalam minyak atsiri daun nilam. Sampel penelitian diambil dari Desa Paruttellang, Kecamatan Ngapa, Kabupaten Kolaka Utara, Provinsi Sulawesi Tenggara. Tahap penelitian ini terdiri dari preparasi sampel, destilasi air, fraksinasi, analisis GC-MS, pemurnian dan identifikasi. Hasil penelitian berupa minyak atsiri daun nilam sebanyak 57 mL yang berwarna kuning muda dan memiliki wangi yang khas. Analisis menggunakan GC-MS terhadap fraksi B, fraksi C, fraksi D dan fraksi E menghasilkan kandungan senyawa patkouli alkohol berturut-turut sebanyak 22,71%; 30,13%; 33,09% dan 22,65%. Isolat D berbentuk kristal putih yang memiliki titik leleh 56 , termasuk dalam senyawa golongan terpenoid, memiliki rumus molekul C15H26O dengan massa molekul 222 gram/mol, identifikasi FTIR menunjukkan adanya gugus O-H, C-H (SP3), C-C metilen (-CH2-CH2), -CH3, dan C-OH alkohol tersier yang merupakan karakteristik dari senyawa patkouli alkohol.Kata Kunci : Daun Nilam (Pogostemon Cablin Benth.), Minyak Atsiri, Patkouli AlkoholThis research aims to determine the amount of patchouli alcohol compound contained in the essential oil of patchouli leaves and the characteristics of the patchouli alcohol compound contained in the essential oil of patchouli leaves. The research sample was taken from Paruttellang Village, Ngapa District, North Kolaka Regency, Southeast Sulawesi Province. This research stage consists of sample preparation, water distillation, fractionation, GC-MS analysis, purification and identification. The results of the research were 57 mL of patchouli leaf essential oil which was light yellow in color and had a distinctive fragrance. Analysis using GC-MS on fraction B, fraction C, fraction D and fraction E resulted in a Patchouli alcohol compound content of 22.71%; 30.13%; 33.09% and 22.65%. Isolate D is white crystals which have a melting point of 56 , included in the terpenoid group of compounds, has the molecular formula C15H26O with a molecular mass of 222 grams/mol, FTIR identification shows the presence of the O-H, C-H (SP3), C-C methylene (-CH2-CH2), -CH3, and C-OH tertiary alcohol which is characteristic of Patchouli alcohol compounds.Keywords: Patchouli Leaves (Pogostemon Cablin Benth.), Essential Oil, Patchouli Alcohol

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45

Wang, Liying, Jianhuang Li, Ying He, et al. "Computer simulation prediction of uranyl ion capture by hetero-sulfide perhydroxycalix[4]arene." Journal of Physics: Conference Series 2390, no. 1 (2022): 012112. http://dx.doi.org/10.1088/1742-6596/2390/1/012112.

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Abstract In order to explore the effect of calix[4]arene hetero-sulfidation on the capture ability of uranyl ions, computer simulations were used to predict that the B3LYP method in density functional theory, the perhydroxycalix[4]arene with different numbers of hetero-sulfur atoms effects on uranyl ion capture ability, and the compounds formed. We gradually replaced the methylene group "-CH2” in the perhydroxycalix[4]arene with "-S-", and combined the substituted perhydroxycalix[4]arene and the uranyl ion to form a complex. Structural optimization was carried out to further verify that the complexes can exist stably after structural optimization. The structural features of the optimized complexes were analyzed, and the molecules of infrared spectroscopy, the binding energy of calix[4]arene to uranyl ion after hybridization S, and the frontier molecular orbital energy levels of the complexes formed were studied. The number of calixarene-hetero-S with the strongest ability to capture uranyl ions and the number of calixarene-hetero-S with the best chemical stability of the complex formed after the capture of uranyl ions were found.

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46

Wiberg, Kenneth B. "Chirality Induced by the Interaction of C═C and C═X Bonds (X═CH2, NH, NH2+, O, and S) Separated by a Methylene Group." Journal of Physical Chemistry A 120, no. 39 (2016): 7771–77. http://dx.doi.org/10.1021/acs.jpca.6b07842.

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47

Schaefer, Ted, and Glenn H. Penner. "Mechanisms of 1H,1H; 1H,13C; and 13C,13C spin–spin coupling constants in benzyl cyanide and some derivatives. Experimental and theoretical estimates of internal rotational potentials." Canadian Journal of Chemistry 64, no. 10 (1986): 2013–20. http://dx.doi.org/10.1139/v86-333.

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The mechanisms of long-range spin–spin coupling constants involving the methylene protons and the 13C nucleus of the cyano group are discussed for benzyl cyanide. Analysis of the 1H nmr spectrum of benzyl cyanide-8-13C in benzene-d6 solution yields nJ(H,CH2) and nJ(H,13CN) for n = 4–6. Similar data are reported for the 2,6-dichloro and 2,6-difluoro derivatives, together with some sign determinations. nJ(13C,13CN), n = 1–5, are given for the three compounds. It is shown that all these parameters are consistent with a small barrier to internal rotation about the [Formula: see text] bond in benzyl cyanide in solution. Computations at various levels of molecular orbital theory agree that this barrier is small. The nJ(13C, 13CN) imply a stabilization in polar solvents of the conformation in which the cyano group of benzyl cyanide lies in a plane perpendicular to the benzene plane. The molecular orbital calculations indicate a predominantly twofold nature of the internal barrier, although a significant fourfold component is also present. The coupling constants cannot discern the presence of the fourfold component for benzyl cyanide nor for its 2,6-difluoro derivative. 1J(13C,13CN) is solvent dependent. A table of the computed sidechain geometries is appended.

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48

Asiwe, Thomas Ndidi, Idongesit Bassey Anweting, Atim Sunday Johnson, Nzikahyel Simon, and Solomon Enejo Shaibu. "Eco-Friendly Synthesis and Characterization of Silver and Zinc Nanoparticles Using Aqueous Extract from the Bark of Antiaris toxicaria." Communication in Physical Sciences 12, no. 1 (2025): 149–61. https://doi.org/10.4314/cps.v12i1.12.

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Silver nanoparticles (AgNPs) and zinc nanoparticles (ZnNPs) were synthesized by a cheap, rapid, and eco-friendly method using aqueous bark extract of Antiaris toxicaria as both the reducing and capping agents. The synthesized AgNPs and ZnNPs were characterized using a UV-visible spectroscopy, Fourier Transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Energy dispersive spectroscopy (EDS). The metal ions (M+ ) were rapidly reduced from M+ to M0 by the aqueous bark extract of Antiaris toxicaria, forming AgNPs and ZnNPs with sizes ranging between 1- 100 nm. The diffraction peaks were indexed to the facecentered cubic (fcc) phase of silver and zinc, indicating that the synthesized AgNPs and ZnNPs were crystalline in nature. Absorption spectra of AgNPs and ZnNPs showed a surface plasmon resonance (SPR) peak around a wavelength of 423 nm and 306 nm respectively. The FTIR spectra revealed distinct peaks at 3295.38 cm1 attributed to the OHgroup which may be responsible for the reduction of M+ to M0 and subsequent formation of metal MNPs, 2104.38 cm-1 corresponding to asymmetric stretching vibrations of methylene (CH2) group in AgNPs, and a sharp peak at 1634.80 cm-1 corresponding to a carbonyl (C=O) group.

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49

Jia, Jinzhang, Yinghuan Xing, Bin Li, et al. "Study on the Occurrence Difference of Functional Groups in Coals with Different Metamorphic Degrees." Molecules 28, no. 5 (2023): 2264. http://dx.doi.org/10.3390/molecules28052264.

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In order to quantitatively study the difference in occurrence content of functional groups in coals with different metamorphic degrees, the samples of long flame coal, coking coal, and anthracite of three different coal ranks were characterized by FTIR and the relative content of various functional groups in different coal ranks was obtained. The semi-quantitative structural parameters were calculated, and the evolution law of the chemical structure of the coal body was given. The results show that with the increase in the metamorphic degree, the substitution degree of hydrogen atoms on the benzene ring in the aromatic group increases with the increase in the vitrinite reflectance. With the increase in coal rank, the content of phenolic hydroxyl, carboxyl, carbonyl, and other active oxygen-containing groups gradually decreased, and the content of ether bonds gradually increased. Methyl content increased rapidly first and then increased slowly, methylene content increased slowly first and then decreased rapidly, and methylene content decreased first and then increased. With the increase in vitrinite reflectance, the OH-π hydrogen bond gradually increases, the content of hydroxyl self-association hydrogen bond first increases and then decreases, the oxygen-hydrogen bond of hydroxyl ether gradually increases, and the ring hydrogen bond first significantly decreases and then slowly increases. The content of the OH-N hydrogen bond is in direct proportion to the content of nitrogen in coal molecules. It can be seen from the semi-quantitative structural parameters that with the increase in coal rank, the aromatic carbon ratio fa, aromatic degree AR and condensation degree DOC increase gradually. With the increase in coal rank, A(CH2)/A(CH3) first decreases and then increases, hydrocarbon generation potential ‘A’ first increases and then decreases, maturity ‘C’ first decreases rapidly and then decreases slowly, and factor D gradually decreases. This paper is valuable for analyzing the occurrence form of functional groups in different coal ranks and clarifying the evolution process of structure in China.

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50

Aginsky, Valery N. "Thin-Layer Chromatography of Inks— Efficiency of Separation of Ink Components." Journal of the American Society of Questioned Document Examiners 22, no. 2 (2019): 13–21. https://doi.org/10.69525/jasqde.259.

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There are numerous publications relating to the use of thin-layer chromatography (TLC) in the analysis of inks on documents. This paper compares the efficiencies of TLC separation of ink components when using several ‘developing’ solvents (solvent systems) commonly used for ink analysis in the forensic laboratory. The parameters chosen for this evaluation are the shape of and distance between chromatographic zones of separated dye components of ink, including components of Methyl Violet, a dye mixture often used in the manufacture of black, violet and blue ballpoint, fountain pen, and stamp pad inks. (This mixture typically consists of the dye Crystal Violet and its two or three homologues, which are triphenylmethane dyes of a similar chemical structure and hence similar physical and chemical properties, whose chemical structures differ only by one methylene [CH2] group). The results obtained show that at least three solvent systems, one of which (ethyl acetate  isopropanol  water  acetic acid  30:15:10:1) was developed and reported by this author in the 1980s, provide significantly improved TLC separation efficiency compared with the “Solvent System I” recommended in the current SWGDOC Standard for Test Methods for Forensic Writing Ink Comparison.

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Journal articles on the topic 'Methylene (-CH2-) Group'

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