Academic literature on the topic 'Methylene (-CH2-) Group'
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Journal articles on the topic "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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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
Books on the topic "Methylene (-CH2-) Group"
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Eland, John H. D., and Raimund Feifel. Molecules with four, five or seven atoms. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198788980.003.0005.
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Double photoionisation spectra of NH3, C2H2, HCHO, C2N2, PCl3, CH4, the methyl halides CH3F, CH3Cl, CH3I, the methylene halides CH2Cl2, CH2Br2, CH2I2, the carbon tetrahalides CF4, CCl4, CBr4, germanium tetrahalides GeCl4, GeBr4, and SF6 are presented with analysis to identify the electronic states of the doubly charged ions. The effects of indirect double ionisation pathways are discussed. There are relatively few important molecules with just four atoms, but most of the ones included here are present and sometimes abundant in planetary and astrophysical environments. The range of five-atom molecules includes methane and all its simple derivatives. Where possible closely related molecules are grouped together in this chapter, as much of the discussion of their electronic structure is the same for all members of a group. This chapter also includes SF6 as a closely related molecule, even though its atom count goes beyond those of some molecules in later chapters.
Book chapters on the topic "Methylene (-CH2-) Group"
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Kumar, M., and R. Gupta. "9 Diamagnetic susceptibility contribution of methylene group (–CH2–) in different classes of organic compounds." In Diamagnetic Susceptibility and Magnetic Anisotropy of Organic Compounds. Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-44736-8_741.
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Mark, James E., Dale W. Schaefer, and Gui Lin. "Types of Polysiloxanes." In The Polysiloxanes. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780195181739.003.0005.
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The polysiloxane of greatest commercial importance and scientific interest is poly(dimethylsiloxane) (PDMS), [Si(CH3)2 –O –]x, a member of the symmetrical dialkyl polysiloxanes, with repeat unit [SiR2 –O –]x. This polymer is discussed extensively in the following chapters, particularly in chapter 5. Other members of this series are poly(diethylsiloxane) [Si(C2H5) –O–]x, and poly(di-n-propylsiloxane) [SiC3H7)2–O–]x. An example of an aryl member of the symmetrically substituted series is poly(diphenylsiloxane), with repeat unit [Si(C6H5)2–O–]x. This polymer is unusual because of its very high melting point and the mesophase it exhibits. The closely related polymer, poly(phenyl/tolylsiloxane), has also been prepared and studied. The unsymmetrically substituted polysiloxanes have the repeat unit [SiRR’O–]x, and are exemplified by poly(methylphenylsiloxane) [Si(CH3) (C6H5) –O–]xand poly(methylhydrosiloxane) [Si(CH3)(H) –O–]x. In some cases, one of the side chains has been unusually long, for example C6H13, C16H33, and C18H37, including a branched side chain—CH(CH3– (CH2)m–CH3. Another example has methoxy-substituted aromatic fragments as one of the two side chains in the repeat unit. Such chains have stereochemical variability in analogy with the vinyl polymers such as polypropylene [CH(CH3) –CH2–]xand vinylidene polymers such as poly(methyl methacrylate) [C(CH3)(C = OOCH3) –CH2–]xOne can also introduce optically active groups as side chains, the simplest example being the secondary butyl group—CH(CH3)(C2H5). Another example involves redox-active dendritic wedges containing ferrocenyl and carbonylchromium moieties. Other substituents have included phenylethenyl groups, cyclic siloxane groups, and Cr-bound carbazole chromophores. In a reversal of roles, some polymers were prepared to have PDMS side chains on a poly(phenylacetylene) main chain. Siloxane-terminated solubilizing side chains are used to improve the properties of thin-film transistors. Silalkylene polymers have methylene groups replacing the oxygen atoms in the backbone. Poly(dimethylsilmethylene) is an example, [Si(CH3)2–CH2]x. A variation on this theme is to include aryl groups, for example, in poly(dimethyldiphenylsilylenemethylene) [Si(CH3)2CH2Si(C6H5)2]x. Other aryl substituents, specifically tolyl groups, have also been included as side chains. It is also possible to insert a silphenylene group [Si(CH3)2–C6H4–] into the backbone of the polysiloxane repeat unit to give [Si(CH3)2–C6H4– Si(CH3)2O–], in which the phenylene can be para or ortho or meta. A specific example is poly(tetramethyl-p-silphenylene-siloxane).
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Venkatesan, Dhanalakshmi, Daya Srinivasan, Senthil Eagappan, and R. A. Sowmiyasree. "AN INVITRO STUDY COMPARING THE MARGINAL SEALING PERFORMANCE OF PIT AND FISSURE SEALANTS." In Emerging Trends in Oral Health Sciences and Dentistry. Technoarete Publishers, 2022. http://dx.doi.org/10.36647/etohsd/2022.01.b1.ch011.
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The goal of this study is to examine and appraise pit and fissure sealants' marginal sealing efficacy . Fifty healthy premolars were selected which was extracted atraumatically for orthodontic treatment and out of which 25 for Group I ( Conseal F )and 25 for Group II ( Embrace Wet Bond). The pit and fissure sealants were applied to the concerned groups, stored in artificial saliva, thermocycled and placed in 1% methylene blue solution . The teeth were rinsed, divided buccolingually and viewed for microleakage with optical stereomicroscope based on the penetration of dye, using Williams B and Winter GB criteria. At 95% confidence level statistical analysis was performed with Mann -Whitney test and chi square test .On comparing the microleakage scores a statistically significance was found (p< 0.001) .Group I (Conseal F ) showed a better marginal sealing efficiency than Group II (Embrace Wet Bond).
Conference papers on the topic "Methylene (-CH2-) Group"
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Demadis, Konstantinos D., Argyri Moschona, Nicoleta Plesu, and Andrew G. Thomas. "Corrosion Control Using Inhibitor Systems Based on Phosphonates and Metal Phosphonate Materials." In CORROSION 2020. NACE International, 2020. https://doi.org/10.5006/c2020-14289.
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Abstract Six systematically varied tetraphosphonate molecules [EDTMP (C2), TDTMP (C4), HDTMP (C6), ODTMP (C8) and DDTMP (C12)] were evaluated as corrosion inhibitors for carbon steel at pH 3. Their interactions with the metal surface were studied by X-Ray Photoelectron Spectroscopy (XPS). The additives belong to the aminomethylene-phosphonate family, and they possess systematically elongated backbone (from two to twelve methylene groups separating the N atoms). The XPS results suggest that the tetraphosphonic acid molecules become significantly deprotonated upon interaction with the carbon steel surface and that the surface interaction of the tetraphosphonic acid family leads to additive adsorption on the steel surface via the phosphonate groups. The mode of corrosion inhibition was studied by potentiodynamic polarization and electrochemical impedance spectroscopy. The results confirm a strong inhibitor adsorption on the metal surface. The nature of the protective layer formed on the carbon steel surface was examined by Attenuated Total Reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and optical microscopy. For selected additives, their synergy with metal ions commonly encountered in water systems was also evaluated. It was found that the phosphonic acid additives form “complexes” with the metal ions on the metallic surface and result in enhanced inhibitory activity. These “metal phosphonate” coatings were studied with a variety of surface techniques, and were also synthesized and structurally characterized, in order to gain a deeper understanding of the true nature of the anti-corrosion coating.
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Saltonstall, Christopher B., John C. Duda, Patrick E. Hopkins, and Pamela M. Norris. "Assesment of Vibrational Coupling at Solid-SAM Junctions." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44314.
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Self-assembled monolayers (SAMs) have recently garnered much interest due to their unique electrical and chemical properties. The limited literature detailing SAM thermal properties has suggested that thermal boundary conductance (TBC) at solid-SAM junctions is not only low, but also insensitive to changes in SAM length as the number of methylene groups (-CH2-) along alkanedithiol chains is varied from 8 to 10. The present study investigates the vibrational spectra of alkanedithiol SAMs as a function of the number of methylene groups forming the molecule backbone via Hartree-Fock methods and the subsequent effects on TBC calculated using a diffuse scattering model. In particular, the vibrational overlap between the alkanedithiol and Au is studied. It is found that despite the addition of 9 new vibrational modes per added methylene group, only one of those modes is elastically accessible to Au. It is believed that this “vibrational inaccessibility” is the cause of the insensitivity of thermal conductance to molecule length.
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Creighton, J. R., and C. M. Truong. "Surface Chemistry of GaAs Atomic Layer Epitaxy." In Microphysics of Surfaces: Nanoscale Processing. Optica Publishing Group, 1995. http://dx.doi.org/10.1364/msnp.1995.mthc1.
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Atomic layer epitaxy (ALE) is a technique which, in principle, yields unparalleled deposition uniformity with precise (i.e. monolayer) thickness control. The technique has been used to deposit compound semiconductors, e.g. GaAs, although the success has not been universally good. In many examples the ALE operating “window” is very small or non-existent. Unintentional carbon doping is another problem which has limited the utility of this technique. In order to address the problems limiting GaAs ALE, we have investigated the surface chemical properties of the standard deposition precursors on GaAs(100) using a variety of surface science diagnostics. Results of these experiments have shed light on the mechanisms of precursor decomposition which lead to film growth and carbon doping. For instance, the kinetics of trimethylgallium (TMGa) decomposition on the Ga-rich and As-rich surfaces, measured by TPD, are in semiquantitative agreement with ALE results. This indicates that the dominant growth mechanism during ALE is heterogeneous in nature. We have also investigated the mechanism of carbon incorporation when using TMGa. Normally, a small fraction of adsorbed methyl (CH3) groups dehydrogenate into methylene (CH2) groups, which are a likely precursor to carbon incorporation. This adsorbate was characterized with vibrational spectroscopies and static SIMS. The rate of CH3 dehydrogenation is consistent with the carbon doping levels obtained during ALE and MOMBE.
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Angappan, Sajeevan, Mudith Karunaratne, Charitha Thambiliyagodage, and Leshan Usgodaarachchi. "Development of Silica-Copper Nanocomposite for Water Purification." In The SLIIT International Conference on Engineering and Technology 2022. Faculty of Engineering, SLIIT, 2022. http://dx.doi.org/10.54389/vodw8508.
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Water pollution is one of the serious concerns across the world at the moment. Industrial wastewater significantly contributes to the negative impacts caused by water pollution. Textile industries discharge large amounts of effluents into water streams with little or no treatment of the discharge because wastewater treatment is an expensive process. Thus, there exists a need for a cheap and effective way to treat textile effluent that contains dyes before being discharged. A high purity silica-based Nano-adsorbent was synthesized by using rice husk as the commercially available main cheap precursor. Copper-loaded silica nanoparticles were successfully functionalized with 3-aminopropyl triethoxysilane (APTES) via the sol-gel pathway to enhance the adsorption performance of organic dyes from textile effluent. The performance of produced Nano-adsorbent was evaluated by using methylene blue as waste adsorbate. As synthesized nanomaterial was characterized by X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy, the XRD results confirmed the presence of silicon dioxide (SiO2) and paramelaconite (Cu4O3) as predicted. The FTIR confirmed the presence of Si–O stretching, N-H bending, C–H stretching, Cu–O stretching and O–H bending vibrations thereby suggesting the presence of SiO2, NH2 groups, CH2, Cu4O3 and physisorbed H2O. The optimum conditions for pH and adsorbent dosage were successfully evaluated for the adsorption process. The optimum pH at which the nanomaterial performed best was at pH 4. The optimum mass of the adsorbent that gave maximum adsorption performance was 20 mg. Kinetic studies revealed that the experimented data was in better correlation with pseudo-second-order kinetics. The outcome of this project would be of interest to textile industries looking for a cheap and effective way to treat textile wastewater. KEYWORDS: Adsorption, APTES, Methylene Blue, Nano adsorbent, Rice Husk, Silica, Sol-gel,
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SAZHIN, SERGEI, and IRINA SHISHKOVA. "Kinetic and MD modelling of automotive fuel droplets heating and evaporation: recent results." In ILASS2017 - 28th European Conference on Liquid Atomization and Spray Systems. Universitat Politècnica València, 2017. http://dx.doi.org/10.4995/ilass2017.2017.4593.
Full textAbstract:
Recent results of the investigation of kinetic and molecular dynamics (MD) models for automotive fuel droplet heating and evaporation are summarised. The kinetic model is based on the consideration of the kinetic region in the close vicinity of the surface of the heated and evaporating droplets, where the motion of molecules is described in terms of the Boltzmann equations for vapour components and air, and the hydrodynamic region away from this surface. The effects of finite thermal conductivity and species diffusivity inside the droplets and inelastic collisions in the kinetic region are taken into account. A new self-consistent kinetic model for heating and evaporation of Diesel fuel droplets is briefly described. The values of temperature and vapour densities at the outer boundary of the kinetic region are inferred from the requirement that both heat flux and mass flux of vapour components in the kinetic and hydrodynamic regions in the vicinity of the interface between these regions are equal. At first, the heat and mass fluxes in the hydrodynamic region are calculated based on the values of temperature and vapour density at the surface of the droplet. Then the values of temperature and vapour density at the outer boundary of the kinetic region, obtained following this procedure, are used to calculate the corrected values of hydrodynamic heat and species mass fluxes. The latter in their turn lead to new corrected values of temperature and vapour density at the outer boundary of the kinetic region. It is shown that this process quickly converges and leads to self-consistent values for both heat and mass fluxes. Boundary conditions at the surface of the droplet for kinetic calculations are inferred from the MD calculations. These calculations are based on the observation that methyl (CH3 ) or methylene (CH2 ) groups in n-dodecane (approximation of Diesel fuel) molecules can be regarded as separate atom-like structures in a relatively simple United Atom Model. Some results of the application of quantum chemical methods to the estimation of the evaporation/condensation coefficient are discussed.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4593