Relevant bibliographies by topics / Ketenes

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Ketenes'

Author: Grafiati
Published: 4 June 2021
Last updated: 31 July 2024

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Journal articles on the topic "Ketenes"

1

Ríos-Gutiérrez, Mar, Andrea Darù, Tomás Tejero, Luis R. Domingo, and Pedro Merino. "A molecular electron density theory study of the [3 + 2] cycloaddition reaction of nitrones with ketenes." Organic & Biomolecular Chemistry 15, no. 7 (2017): 1618–27. http://dx.doi.org/10.1039/c6ob02768g.

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The zw-type 32CA reactions of nitrones with ketenes are controlled by the nucleophilic character of the nitrone and the electrophilic character of the ketene. They are chemo- and regio-selective and the use of electrophilic ketenes changes the mechanism from one-step to two-step.
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2

Andraos, J., Y. Chiang, S. J. Eustace, A. J. Kresge, S. W. Paine, V. V. Popik, and K. Sung. "Article." Canadian Journal of Chemistry 77, no. 4 (April 1, 1999): 459–62. http://dx.doi.org/10.1139/v99-058.

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Five ketenes, phenyl(ethyl)ketene, phenyl(methylthio)ketene, diphenylketene, pentafluorophenylketene, and 1-naphthylketene, were generated flash photolytically and solvent isotope effects (H2O vs. D2O) on their hydroxide-ion-catalyzed hydration in aqueous solution were determined. The values obtained are all weakly inverse and closely similar (kHO/kDO = 0.76-0.97), as expected for these fast, hydroxide-ion-consuming reactions, known to proceed by nucleophilic attack of hydroxide on the ketene carbonyl group. The characteristic magnitude of these isotope effects should prove useful in identifying new examples of this reaction.Key words: ketenes, flash photolysis, photo-Wolff reaction, solvent isotope effects on hydroxide ion consumption.
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Ahmed, Issahaku, Richard Tia, and Evans Adei. "A density functional theory study of the mechanisms of addition of transition metal oxides ReO3L(L = Cl-, O-, OCH3, CH3) to substituted ketenes." Journal of Theoretical and Computational Chemistry 14, no. 05 (August 2015): 1550035. http://dx.doi.org/10.1142/s0219633615500352.

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Ketenes are excellent precursors for catalytic asymmetric reactions, creating chiral centers mainly through addition across their C = C bonds. Density functional theory (DFT) calculations at the MO6/LACVP* and B3LYP/LACVP* levels of theory were employed in a systematic investigation of the peri-, chemo- and regio-selectivity of the addition of transition metal oxo complexes of the type ReO 3 L ( L = Cl -, O -, OCH 3, CH 3) to substituted ketenes O = C = C ( CH 3)(X) [ X = CH 3, H , CN , Ph ] with the aim of elucidating the effects of substituents on the mechanism of the reactions. The [2 + 2] addition pathway across the C = C or C = O (depending on the ligand) is the most preferred in the reactions of dimethyl ketene with all the metal complexes studied. The [2 + 2] pathway is also the most preferred in the reactions of ReO 3 Cl with all the substituted ketenes studied except when X = Cl . Thus of all the reactions studied, it is only the reaction of ReO 3 Cl with O = C = C ( CH 3)( Cl ) that prefers the [3 + 2] addition pathway. Reactions of dimethyl ketene with ReO 3 L favors addition across C = O bonds of the ketene when L = O - and CH 3 but favors addition across C = C bonds when L = OCH 3 and Cl . In the reactions of ReO 3 Cl with substituted ketenes, addition across C = O bonds is favored only when X = H while addition across C = C bonds is favored when X = CH 3, Cl , Ph , CN . The reactions of dimethyl ketene with ReO 3 L will most likely lead to the formation of an ester precursor in each case. A zwitterionic intermediate is formed in the reactions except in the reactions of [Formula: see text]. The order in the activation energies of the reactions of dimethyl ketenes with the metal complexes ReO 3 L with respect to changing ligand L is O - < CH 3 O - < Cl - < CH 3 while the order in reaction energies is CH 3 < CH 3 O - < O - < Cl -. For the reactions of substituted ketenes with ReO 3 Cl , the order in activation barriers is CH 3 < Ph < CN < Cl < H while the reaction energies follow the order Cl < CH 3 < H < Ph < CN . In the reactions of dimethyl ketenes with ReO 3 L , the trend in the selectivity of the reactions with respect to ligand L is Cl - < CH 3 O - < CH 3 < O - while the trend in selectivity is CH 3 < CN < Cl < Ph in the reactions of ReO 3 Cl with substituted ketenes. It is seen that reactions involving a change in oxidation state of metal from the reactant to product have high activation barriers while reactions that do not involve a change in oxidation state have low activation barriers. For both [3 + 2] and [2 + 2] additions, low activation barriers are obtained when the substituent on the ketene is electron-donating while high activation barriers are obtained when the substituent is electron-withdrawing.
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4

Lystsova, Ekaterina A., Ekaterina E. Khramtsova, and Andrey N. Maslivets. "Acyl(imidoyl)ketenes: Reactive Bidentate Oxa/Aza-Dienes for Organic Synthesis." Symmetry 13, no. 8 (August 17, 2021): 1509. http://dx.doi.org/10.3390/sym13081509.

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Polyfunctional building blocks are essential for the implementation of diversity-oriented synthetic strategies, highly demanded in small molecule libraries’ design for modern drug discovery. Acyl(imidoyl)ketenes are highly reactive organic compounds, bearing both oxa- and aza-diene moieties, conjugated symmetrically to the ketene fragment, enabling synthesis of various skeletally diverse heterocycles on their basis. The highlights of reactions utilizing acyl(imidoyl)ketenes are high yields, short reaction time (about several minutes), high selectivity, atom economy, and simple purification procedures, which benefits the drug discovery. The present review focuses on the approaches to thermal generation of acyl(imidoyl)ketenes, patterns of their immediate transformations via intra- and intermolecular reactions, including the reactions of cyclodimerization, in which either symmetric or dissymmetric heterocycles can be formed. Recent advances in investigations on mechanisms, identifications of intermediates, and chemo- and regioselectivity of reactions with participation of acyl(imidoyl)ketenes are also covered.
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Allen, Annette D., A. Jerry Kresge, Norman P. Schepp, and Thomas T. Tidwell. "Hydration reactivity of ketenes generated by flash photolysis." Canadian Journal of Chemistry 65, no. 8 (August 1, 1987): 1719–23. http://dx.doi.org/10.1139/v87-287.

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The ketenes n-BuCH=C=O, PhCH=C=O, and Ph2C=C=O have been generated by flash photolysis and their reactivities toward water, including acid and base catalysis, have been measured in wholly aqueous media by ultraviolet spectrophotometry. The phenyl group electronically enhances the reactivity of ketenes relative to n-butyl toward water and hydroxide, but retards reaction with protic acids. The presence of bulky groups, including phenyls, on each side in the ketene plane sterically retards nucleophilic attack. The reactions are interpreted as involving in-plane attack by nucleophilic water or hydroxide in the neutral and base-induced reactions, and electrophilic protonation perpendicular to the ketene plane for the acid-catalyzed reaction.
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6

Brook, Adrian G., and Abraha Habtemariam. "Insertion reactions of nitrosobenzene and ketenes into silaaziridines." Canadian Journal of Chemistry 81, no. 11 (November 1, 2003): 1164–67. http://dx.doi.org/10.1139/v03-001.

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Nitrosobenzene, trimethylsilyl ketene, and diphenylketene insert into the ring of silaaziridines to yield relatively unstable 5-membered heterocyclic ring systems. The new compounds, which have been characterized by 1H, 13C, and 29Si NMR spectroscopy, arise from two different modes of insertion into the ring Si—N bond, leading to compounds with an exocyclic C=N bond (from nitrosobenzene) or two exocyclic C=C bonds (from the ketenes).Key words: silaaziridines, ring insertion, nitrosobenzene, ketenes, heterocyclic rings.
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7

Jörges, Mike, Felix Krischer, and Viktoria H. Gessner. "Transition metal–free ketene formation from carbon monoxide through isolable ketenyl anions." Science 378, no. 6626 (December 23, 2022): 1331–36. http://dx.doi.org/10.1126/science.ade4563.

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The capacity of transition metals to bind and transform carbon monoxide (CO) is critical to its use in many chemical processes as a sustainable, inexpensive C1 building block. By contrast, only few s- and p-block element compounds bind and activate CO, and conversion of CO into useful carbonyl-containing organic compounds in such cases remains elusive. We report that metalated phosphorus ylides provide facile access to ketenyl anions ([RC=C=O] – ) by phosphine displacement with CO. These anions are very stable and storable reagents with a distinctive electronic structure between that of the prototypical ketene (H 2 C=C=O) and that of ethynol (HC≡C–OH). Nonetheless, the ketenyl anions selectively react with a range of electrophiles at the carbon atom, thus offering high-yielding and versatile access to ketenes and related compounds.
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Andraos, John, and A. Jerry Kresge. "Correlation of rates of uncatalyzed and hydroxide-ion catalyzed ketene hydration. A mechanistic application and solvent isotope effects on the uncatalyzed reaction." Canadian Journal of Chemistry 78, no. 4 (April 1, 2000): 508–15. http://dx.doi.org/10.1139/v00-032.

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Rates of hydration of a number of ketenes were measured in neutral and basic solution using flash photolytic techniques, and rate constants for their uncatalyzed, kuc, and hydroxide-ion catalyzed, kHO, reactions were determined. These results, plus additional data from the literature, were found to provide the remarkably good correlation log kuc = -3.21 + 1.14 log kHO, which spans 10 orders of magnitude in reactivity and includes 31 ketenes. This good correlation implies that uncatalyzed and hydroxide-ion catalyzed ketene hydraton occur by similar reaction mechanisms, which for the hydroxide-ion catalyzed process is known to involve nucleophilic attack on the carbonyl carbon atom of the ketene. Rate constants for phenylhydroxyketene, on the other hand, do not fit this correlation, which suggests that the mechanistic assignment upon which these rate constants are based may not be correct. Solvent isotope effects on these uncatalyzed ketene hydrations are weak; most are less than kH/kD = 2. It is argued that these isotope effects are largely, if not entirely, secondary in nature and that they are consistent with both a reaction mechanism in which nucleophlic attack of a single water molecule on the ketene carbonyl carbon atom produces a zwitterionic intermediate and also a mechanism that avoids this intermediate by passing through a cyclic transition state involving several water molecules.Key words: ketene hydration, rate correlation, nucleophilic attack, solvent isotope effects, phenylhydroxyketene.
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McAllister, Michael A., and Thomas T. Tidwell. "Structural and substituent effects on the ketene infrared stretching frequency." Canadian Journal of Chemistry 72, no. 3 (March 1, 1994): 882–87. http://dx.doi.org/10.1139/v94-115.

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The frequencies and intensities of the ketene asymmetric stretching vibration near 2100 cm−1 for a series of substituted ketenes and fulvenones have been calculated using ab initio molecular orbital methods. Comparisons of the calculated values with experimentally determined results show reasonably good agreement in most cases, with a typical deviation of ± 10 cm−1 between the measured and calculated values. A test of a correlation proposed by Gano and Jacob (Spectrochim. Acta, 43A, 1023 (1987)) of the frequencies with substituent field and resonance parameters F and R shows a modest correlation coefficient of 0.86, with no significant dependence on R. These results are consistent with enhancements of ketene infrared absorption frequencies by interaction of substituents with the negative charge density at Cβ of ketenes, as indicated by the resonance structure [Formula: see text] The calculated intensities I (km/mol) for non-π acceptor substituents are correlated with the group electronegativities X by the relationship I = 1841.6 − 305.7X (r = 0.94). The π-acceptor substituents show exaltations of the intensities, and the results are interpreted as showing an enhancement of intensities by electropositive substituents increasing the normal ketene dipole directed towards oxygen, and an opposite effect by π-acceptor substituents delocalizing the negative charge at Cβ.
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Fu, Nanyan, Annette D. Allen, Winnie Chan, Shinjiro Kobayashi, Thomas T. Tidwell, Daryoush Tahmassebi, Angelica Aguilar, Eduardo Peña Cabrera, and Jazmin Godoy. "Generation, observation, and reactivity of furyl- and thienylketenes and bisketenes." Canadian Journal of Chemistry 86, no. 4 (April 1, 2008): 333–41. http://dx.doi.org/10.1139/v08-021.

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2- and 3-Furylketenes (18 and 20), 2- and 3-thienylketenes (19 and 21), and bis(2,5-ketenyl)thiophene (24) have been generated as observable reactive intermediates by photochemical Wolff rearrangements. Stabilization energies of the monoketenes 18–21 have been determined by DFT computations of isodesmic energy changes, and these ketenes are predicted to be modestly destabilized relative to phenylketene. Rate constants for reaction of 18–21 with H2O and with n-BuNH2 have been measured and are similar to those of the 2-, 3-, and 4-pyridylketenes (1). The product of reaction of 2-furylketene (18) with H2O is calculated to be stable as an acid enol, and reaction of 18 with the stable free radical TEMPO forms a stable ester enol, consistent with stabilization by intramolecular H-bonding to the furyl oxygen. Bis(thienyl)-1,2-bisketenes 26 and 28 have been generated by photochemical cyclobutenedione ring opening and are highly reactive in ring closure. This is attributed to destabilization of the ketenes and stabilization of the cyclobutenediones by the electron donating aryl groups.Key words: ketenes, furans, thiophenes, reactive intermediates, photolysis, mechanisms.
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Dissertations / Theses on the topic "Ketenes"

1

Giang, Yun-Seng F. (Yun-Seng Frank). "Intramolecular 2+2 Cycloadditions of Ketenes." Thesis, North Texas State University, 1986. https://digital.library.unt.edu/ark:/67531/metadc331159/.

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The objective of this study was to explore intramolecular ketene cycloadditions with the anticipated results of developing new synthetic methodology for the synthesis of polycyclic compounds difficult to obtain by other procedures. (o-Alkenylphenoxy)ketenes were initially selected for this study because these ketenes provided a favorable proximity for the intramolecular [2+2] cycloaddition reactions. The difunctional precursors, (o-alkenylphenoxy)- acetic acids, were readily prepared from o-alkenylphenols and ∝-halocarboxylic acids and were converted to the corresponding acid chlorides by reaction with oxalyl chloride. The acid chlorides were dehydrochlorinated to the corresponding (o-alkenylphenoxy)ketenes by treatment with triethylamine. The ketenes undergo a facile intramolecular [2+2] cycloaddition to give polycyclic eye 1obutanones. The (o-vinylphenoxy)ketenes are clearly more reactive than the (o-allylphenoxy)ketenes and provide much better yields of the cycloaddition products because of electronic effects in the transition state in the cycloaddition process. The intramolecular [2+2] cycloadditions of keteniminium salts were included in this study as a more electrophilic alternative to ketenes that will react with less nucleophilic carbon-carbon double bonds. However, the use of keteniminium salts instead of ketenes in Intramolecular cycloadditions does have some limitations. The synthesis of benzofurans via the intramolecular [2+2] cycloadditions of (o-acylphenoxy)ketenes was accomplished. The initially formed ß-lactone cycloaddition products spontaneously underwent decarboxylation to the benzofurans. The aromaticity of the benzofurans is apparently a very strong driving force for the cycloaddition. During the course of this study, two new synthetic methods were discovered which in many instances represent a significant Improvement over existing methods. The Wittig Reactions of ketoacids without protecting the carboxyl groups provide a reliable source of the precursor unsaturated acids needed for intramolecular ketene-olefin cycloadditions. Also, the one-pot preparation of intramolecular ketene cycloaddition products from the carboxylic acid via the tosylate represents a new synthetic method. This procedure eliminates the acid halide preparation, isolation and purification step, thereby significantly simplifying the synthesis.
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Palmer, Prem. "Structure, Energetics and Reactions of Bisketenes: An Ab Initio and Density Functional Theory Study." Thesis, University of North Texas, 1997. https://digital.library.unt.edu/ark:/67531/metadc501272/.

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The effect of varying substituents on structure and energies of bisketenes was studied using ab initio methods. Effect of substituents on ring closing reaction of bisketenes to the corresponding cyclobutenediones was also studied using ab initio methods. One or two of the following substituents were used to study the effect of varying substituents: BH2, CH3, NH2, OH, F, AlH2, SiH3, PH2, SH, Cl. Studies were done at the Hartree-Fock (HF), Møller-Plesset (MP2), and Density Functional Theory (B3LYP) levels of theory using the 6-31G* basis set.
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Jiang, Bo. "Homo- and co-polymerization of disubstituted ketenes." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMIR02/document.

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Ce travail vise à synthétiser avec un rendement satisfaisant de nouvelles architectures de polymères à hautes performances, possédant une structure définie et une bonne fenêtre de transformation, sur la base de cétènes aliphatiques ou aromatiques disubstitués. Les synthèses de diméthylcétène (DMK), méthyléthylcétène (MEK), diéthylcétène (DEK), éthylphénylcétène (EPK) et diphénylcétène (DPK) ont été étudiées. Puis l’homo- et la copolymérisation de ces monomères avec différents amorceurs ont été étudiées. L’influence de l’encombrement stérique présent sur les cétènes influence grandement leur réactivité. Ainsi, des mélanges DMK / DEK et DMK / DPK ont été copolymérisés avec succès pour donner des polycétones dont les propriétés thermiques présentent une plage de transformation satisfaisante (Tf ~ 160°C et Td₅% ~ 260°C). Le DMK est le seul monomère conduisant à un homopolymère par voie cationique classique. Les tentatives de photopolymérisation cationique n’ont pas conduit à la polycétone attendue. L’utilisation de métallocènes conduit à la structure polyester. Des structures semi cristallines de très haute masse molaire et faible polydispersité ont été ainsi obtenues (Mn ~ 300000 g·mol−1, Ɖ < 2, Tg ~ 70°C, Tf ~ 200°C,Td₅% ~ 330°C)
This study is aimed at synthesizing with a satisfying yield new architectures of high performance polymers, possessing a neat structure and good processing window, on the basis of disubstituted aliphatic or aromatic ketenes. The synthesis of dimethylketene (DMK), methylethylketene (MEK), diethylketene (DEK), ethylphenylketene (EPK) and diphenylketene (DPK) were approached. Then homo and copolymerization of these monomers with different initiators were studied. The influence in steric hindrance of the monomers affected their reactivity. Thus copolymers based on DMK/ DEK and DMK / DPK were successfully obtained and afforded polyketones having good thermal properties and processing window (Tm ~ 160°C and Td₅% ~ 260°C). Only DMK homopolymerized by classic cationic initiation. Photopolymerization did not lead to any polymer formation. Initiation with metallocenes polymerized DMK to a crystallized polyester in an insertion chain growth mechanism. Excellent properties (Mn ~300 000 g·mol−1, Tg ~ 70°C, Tm ~ 200°C, Td₅% ~ 330°C) were obtained
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Rafai, Far Adel. "Polymer-bound ketenes and allenes, preparation and applications." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0026/NQ49839.pdf.

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5

Gu, Yi Qi. "Intramolecular [2+2] Cycloadditions of Phenoxyketenes and Intermolecular [2+2] Cycloadditions of Aminoketenes." Thesis, University of North Texas, 1989. https://digital.library.unt.edu/ark:/67531/metadc332334/.

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One objective of this study was to explore the intramolecular [2+2] cycloadditions of phenoxyketenes to carbonyl groups with isoflavones and benzofurans as target compounds. The other objective was to investigate the eyeloaddition reactions of rarely studied aminoketenes. The conversion of 2-(carboxyalkoxy)benzils to the corresponding phenoxyketenes leads to an intramolecular [2+2] cycloaddition to ultimately yield isoflavones and/or 3-aroylbenzofurans. The product distributions are dependent upon the substitution pattern in the original benzil acids. The initial cycloaddition products, β-lactones, are isolated in some instances while some β-lactones spontaneously underwent decarboxylation and could not be isolated. The ketene intermediate was demonstrated in the intramolecular reaction of benzil acids or ketoacids with sodium acetate and acetic anhydride. It is suggested that sodium acetate and acetic anhydride could serve as a source for the generation of ketenes directly from certain organic acids. The treatment of ketoacids with acetic anhydride and sodium acetate provides a simpler procedure to prepare benzofurans than going through the acid chloride with subsequent triethylamine dehydrochlorination to give the ketenes. N-Ary1-N-alkylaminoketenes were prepared for the first time from the corresponding glycine derivatives by using p-toluenesulfonyl chloride and triethylamine. These aminoketenes underwent in situ cycloadditions with cyclopentadiene, cycloheptene and cyclooctenes to yield only the endo -bicyclobutanones. The cycloheptene and cyclooctene cycloaddition products underwent dehydrogenation under the reaction conditions to yield bicycloenamines. A mechanism is proposed for this dehydrogenation involving a radical cation of the arylalkylamine. (N-Phenyl-N-methyl) aminomethylketene was also prepared and found to undergo an intramolecular Friedel-Crafts type acylation to yield an indole derivative when prepared by the acetic anhydride, sodium acetate method. The in situ cycloaddition of N-aryl-N-alkyl aminoketenes with various imines was found to form predominately cis-3-amino-2-azetidinones. A mechanism involving a dipolar intermediate is provided whereby the structure of the intermediate is determined by both electronic and steric effects. The stereochemistry of the resulting β-lactams is dependent upon the structure of the dipolar intermediate.
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Tickner, Christopher Alan. "Alkaloid catalysed addition to ketenes : a method for asymmetric synthesis." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416878.

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Winders, J. A. "Synthesis of natural products via intramolecular trapping of photogenerated ketenes." Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381729.

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Xiang, Yuanhui. "SILYL KETENES AS BUILDING BLOCKS FOR SMALL MOLECULES AND POLYMERS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1561113802285453.

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Taggi, Andrew Edmund. "The development of novel methodology for catalytic asymmetric synthesis ketenes." Available to US Hopkins community, 2003. http://wwwlib.umi.com/dissertations/dlnow/3080776.

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Kumar, Ganesh Angusamy. "Substituent Effects: A Computational Study on Stabilities of Cumulenes and Low Barrier Hydrogen Bonds." Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2566/.

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The effect of substituents on the stabilities of cumulenes-ketenes, allenes, diazomethanes and isocyanates and related systems-alkynes, nitriles and nitrile oxides is studied using the density functional theory (B3LYP, SVWN and BP86) and ab initio (HF, MP2) calculations at the 6-31G* basis set level. Using isodesmic reactions, correlation between stabilization energies of cumulenes and substituent group electronegativities (c BE) is established and the results from DFT and MP2 methods are compared with the earlier HF calculations. Calculations revealed that the density functional methods can be used to study the effect of substituents on the stabilities of cumulenes. It is observed that the cumulenes are stabilized by electropositive substituent groups from s -electron donation and p -electron withdrawal and are destabilized by electronegative substituent groups from n-p donation. The calculated geometries of the cumulenes are compared with the available experimental data.High level ab initio and density functional theory calculations have been used to study the energetics of low-barrier hydrogen bond (LBHB) systems. Using substituted formic acid-formate anion complexes as model LBHB systems, hydrogen bond strength is correlated to the pKa mismatch between the hydrogen bond donor and the hydrogen bond acceptor. LBHB model systems are characterized by the 1H-NMR chemical shift calculations. A linear correlation between the calculated hydrogen bond strength and the predicted 1H-NMR chemical shift was established. It is concluded that the pKa matching within the enzyme active site of the two species involved in the LBHB is important to maximizing catalytic stabilization.
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Books on the topic "Ketenes"

1

Tidwell, Thomas T. Ketenes. New York: Wiley, 1995.

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Tidwell, Thomas T. Ketenes. New York: John Wiley & Sons, Ltd., 2006.

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Tidwell, Thomas T. Ketenes II. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2005. http://dx.doi.org/10.1002/0471767670.

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Tidwell, Thomas T. Ketenes II. 2nd ed. Hoboken, N.J: Wiley-Interscience, 2006.

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Ruane, Patrick H. The synthesis and detection of monoalkyl-aryl ketenes and ketenimines. Dublin: University College Dublin, 1997.

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Rowell, Roger M. Flakeboards made from aspen and southern pine wood flakes reacted with gaseous ketene. Madison, WI: [Forest Products Laboratory, 1987.

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Drayton, C. J. Cumulative index. Stuttgart: Thieme, 2008.

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Savolainen, Raija. The use of branched ketene dimers in solving the deposit problems related to the internal sizing of uncoated fine paper. Lappeenranta, Finland: Lappeenranta University of Technology, 2001.

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Winders, John Alexander. Synthesis of natural products via intramolecular trapping of photogenerated ketenes. Salford: University of Salford, 1988.

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Rahman, Shahzad Sharooq. Generation of ketenes by photolysis of cyclobutanones: A versatile route to natural product synthesis. Salford: University of Salford, 1988.

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Book chapters on the topic "Ketenes"

1

Pannell, Keith H., and Adrian M. Haiduc. "Insertion of Aldehydes, Ketones, and Ketenes." In Inorganic Reactions and Methods, 474–75. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145296.ch285.

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Davies, A. G. "Insertion Reactions of Ketenes, Alkenes, and Alkynes." In Inorganic Reactions and Methods, 465–68. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145296.ch281.

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von Angerer, S., and S. L. Warriner. "Synthesis from Ketenes and Ketene Acetals." In Acetals: Hal/X and O/O, S, Se, Te, 1. Georg Thieme Verlag KG, 2007. http://dx.doi.org/10.1055/sos-sd-029-00380.

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"Ketenes (I)." In Substance index : from the 4th edition and the additional and supplementary volumes to the 4th edition, edited by Backes, Fröhlich, and Padeken. Stuttgart: Georg Thieme Verlag, 2000. http://dx.doi.org/10.1055/b-0035-114352.

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"Ketenes (II)." In Substance index : from the 4th edition and the additional and supplementary volumes to the 4th edition, edited by Backes, Fröhlich, and Padeken. Stuttgart: Georg Thieme Verlag, 2000. http://dx.doi.org/10.1055/b-0035-114353.

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"Ketenes (III)." In Substance index : from the 4th edition and the additional and supplementary volumes to the 4th edition, edited by Backes, Fröhlich, and Padeken. Stuttgart: Georg Thieme Verlag, 2000. http://dx.doi.org/10.1055/b-0035-114354.

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"Ketenes (VI)." In Substance index : from the 4th edition and the additional and supplementary volumes to the 4th edition, edited by Backes, Fröhlich, and Padeken. Stuttgart: Georg Thieme Verlag, 2000. http://dx.doi.org/10.1055/b-0035-114355.

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"Ketenes (V)." In Substance index : from the 4th edition and the additional and supplementary volumes to the 4th edition, edited by Backes, Fröhlich, and Padeken. Stuttgart: Georg Thieme Verlag, 2000. http://dx.doi.org/10.1055/b-0035-114356.

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"Ketenes (VI)." In Substance index : from the 4th edition and the additional and supplementary volumes to the 4th edition, edited by Backes, Fröhlich, and Padeken. Stuttgart: Georg Thieme Verlag, 2000. http://dx.doi.org/10.1055/b-0035-114357.

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"Ketenes (VII)." In Substance index : from the 4th edition and the additional and supplementary volumes to the 4th edition, edited by Backes, Fröhlich, and Padeken. Stuttgart: Georg Thieme Verlag, 2000. http://dx.doi.org/10.1055/b-0035-114358.

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Conference papers on the topic "Ketenes"

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Brungardt, C. L., and D. F. Varnell. "The Effect of Ketene Dimer Melting Point on the Rate of Sizing Development." In Advances in Paper Science and Technology, edited by S. J. I’Anson. Fundamental Research Committee (FRC), Manchester, 2005. http://dx.doi.org/10.15376/frc.2005.2.1317.

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Two studies were carried out in an effort to gain a better understanding of how ketene dimers develop sizing. In the first study, eight ketene dimers with a range of melting points, vapor pressures, and molecular weights were evaluated for rate of sizing development. Ketene dimer melting point had a clear effect on the rate of sizing development. High melting ketene dimers initiated sizing at higher sheet moistures than low melting dimers. High melting dimers also developed their ultimate level of sizing faster than low melting ketene dimers. These results suggest that solid and liquid ketene dimers have different mechanisms of sizing development. Ketene dimer vapor pressure and molecular weight had no consistent effects on the rate of sizing development. Pseudo first order rate constants for sizing development were then measured for a high melting solid ketene dimer and a liquid ketene dimer over dryer temperatures ranging from 55 °C to 85 °C. The rate constants measured for the liquid ketene dimer increased steadily as dryer temperature increased. An Arrhenius plot of the rate constants obtained for the liquid ketene dimer yielded an activation energy of 11 kcal per mole for sizing development. These results are consistent with the hypothesis that the chemical reaction of the lactone ring is the rate determining step in sizing development for liquid ketene dimers. The high melting solid ketene dimer followed more complex kinetics and probably developed sizing by a combination of mechanisms. It is likely that the differing sizing responses measured for the solid and liquid ketene dimers are due to differing sizing contributions from the unreacted and hydrolyzed ketene dimers.
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Roberts, J. C., D. N. Garner, and U. D. Akpabio. "Neutral Sizing and the Mechanism of Alkyl Ketene Dimer Sizing." In Papermaking Raw Materials, edited by V. Punton. Fundamental Research Committee (FRC), Manchester, 1985. http://dx.doi.org/10.15376/frc.1985.2.815.

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The principle of reactive sizing is discussed, and the variety of sizes which have been considered is reviewed. The reactivity of tetradecyl ketene dieter towards water and model compounds for cellulose has been shown to be very low and the results suggest that very little ß -keto ester formation would be expected under normal papermaking conditions. A study has also been made of the retention of C-14 labelled tetradecyl ketene dimer in laboratory handsheets, and of the degree of sizing which is induced. The results show that the dieter is present in the sheet predominantly in its unreacted form, but that a small percentage is present in a form which is not amenable to extraction by chloroform. This residual size exerts a considerable sizing effect, and the amount present in the sheet is related to the curing conditions used. The nature of the unextractable material has been studied by mild hydrolysis and the results are compatible with a low level of ß -keto ester formation. Comparisons have been made with C-14 labelled hexadecyl hexadecanoate, a compound of similar structure and physical characteristics but which is unable to undergo reaction with cellulose. A study has also been made of the influence of aluminium sulphate on alkyl ketene dieter sizing. The retention of size in sheets made in the presence of aluminium sulphate is reduced, but not to a sufficiently low level to account for the loss in sizing which is observed. An explanation in terms of the inhibition of reaction of the dieter with cellulose as a result of adsorbed aluminium species is proposed.
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Ashikhmin, Michael V., Axel Mellinger, and C. B. Moore. "Photodissociation of singlet ketene by two-step IR+UV excitation." In Optoelectronics and High-Power Lasers & Applications, edited by John W. Hepburn, Robert E. Continetti, and Mark A. Johnson. SPIE, 1998. http://dx.doi.org/10.1117/12.308388.

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Junkers, Thomas, Stephan Kobben, and Anitha Ethirajan. "Synthesis of Degradable PolyMMA via Copolymerization with Cyclic Ketene Acetals." In 1st International Electronic Conference on Materials. Basel, Switzerland: MDPI, 2014. http://dx.doi.org/10.3390/ecm-1-d002.

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Margulès, L., Y. Ellinger, J. C. Guillemin, Jose Cernicharo, Belén Tercero, R. Motiyenko, and Celina Bermúdez. "MILLIMETER WAVE SPECTRUM OF METHYL KETENE AND ITS SEARCH IN ORION." In 72nd International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2017. http://dx.doi.org/10.15278/isms.2017.wf09.

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Zou, Y., J. Feng, J. Li, and C. Ye. "Study on the nonlinear optical properties of substituted ketene N,S-acetals." In International Conference on Science and Technology of Synthetic Metals. IEEE, 1994. http://dx.doi.org/10.1109/stsm.1994.835734.

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Rajzmann, Michel, Agnés Pommier, Jean-Marc Pons, Philippe Thomas, and André Baldy. "A semiempirical theoretical study of the [2+2] cycloaddition between ketene and formaldehyde." In The first European conference on computational chemistry (E.C.C.C.1). AIP, 1995. http://dx.doi.org/10.1063/1.47652.

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Yu, Laipu, and Gil Garnier. "Mechanism of Internal Sizing with Alkyl Ketene Dimers: The Role of Vapour Deposition." In The Fundamentals of Papermaking Materials, edited by C. F. Baker. Fundamental Research Committee (FRC), Manchester, 1997. http://dx.doi.org/10.15376/frc.1997.2.1021.

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The role played by AKD vapours during internal sizing was investigated using commercial AKD waxes and model surfaces. The model surfaces consist of cellulose and cellulose acetate films deposited on smooth glass slides. These cellulosic films were exposed to AKD vapours at temperatures ranging from 80 degrees C to 175 degrees C for different periods of time. The extent of sizing was followed by measuring the advancing contact angle of water over the treated surfaces. A simple model, considering both physisorption and chemical reaction, was developed and validated with experimental data. The energy of activation of 61 .4 kJ/mole was derived from the Arrhenius plot . From a series of indirect techniques, it is concluded that the establishment of a covalent bond between cellulose and AID is essential in order to introduce permanent hydrophobicity to cellulosic surfaces. The effect of “sizing promoters” on the reaction rate was also examined. Both NaHC03 and cationic PEI failed to catalyze sizing between cellulose and AKD vapours. The mechanism proposed and the model will shed new light on the phenomena of AKD sizing treatment and sizing migration.
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Kolesniková, Lucie, Stepan Urban, J. C. Guillemin, Patrik Kania, Tereza Uhlíková, Kateřina Luková, Karel Vávra, and Jan Koucký. "THE MILLIMETER WAVE SPECTRA OF VINYL ISOCYANATE AND VINYL KETENE, CANDIDATES FOR ASTRONOMICAL OBSERVATIONS." In 2022 International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2022. http://dx.doi.org/10.15278/isms.2022.wn10.

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Drabbels, Marcel, Christopher G. Morgan, David S. McGuire, and Alec M. Wodtke. "Vibronically-resolved measurement of correlated product-state distributions of ketene photolysis at 308 nm." In Modern Spectroscopy of Solids, Liquids, and Gases. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/msslg.1995.sfa2.

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One of the most fundamental observables of the prototypical photodissociation reaction, AB + ħω →A + B, is the correlated-product-state distribution, P n ¯ A , n ¯ B , which gives the probability that fragment A is produced in quantum state n _ A when fragment B is simultaneously produced in quantum state n _ B . Determination of P n ¯ A , n ¯ B is possible through quantum-state-specific translational energy measurements.
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Reports on the topic "Ketenes"

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Beldman, Alfons, Anne-Charlotte Hoes, Carlijn Savelkouls, and Gemma Tacken. Verwaarden van duurzame ketens. Den Haag: Wageningen University & Research, 2017. http://dx.doi.org/10.18174/402697.

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Bremmer, Johan, Bas Janssens, Marc Ruijs, Jan Benninga, Robert Stokkers, Gerben Splinter, Pepijn Smit, Linda Puister-Jansen, and Dóra Lakner. Plantaardige ketens in beeld. Wageningen: Wageningen Economic Research, 2019. http://dx.doi.org/10.18174/494597.

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van der Schans, J. W., and D. van Wonderen. Korte ketens in Gelderland. Wageningen: Wageningen Economic Research, 2019. http://dx.doi.org/10.18174/495050.

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Berkhout, Petra, Ron Bergevoet, and Allard Jellema. Knelpuntenanalyse conflict Oekraïne : analyse knelpunten korte termijn voor de agrarische ketens. Wageningen: Wageningen Economic Research, 2022. http://dx.doi.org/10.18174/566959.

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van de Vis, Hans, Martien Bokma-Bakker, and Edward Schram. Risico-evaluatie dierenwelzijn in ketens van vissen, schaal- en schelpdieren : Deskstudie en expertopinie. Wageningen: Wageningen Livestock Research, 2019. http://dx.doi.org/10.18174/577460.

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Vaghjiani, Ghanshyam L. Investigations of the CO-Chemiluminescence in the Reaction of Ketene With Excess Oxygen Atoms. Fort Belvoir, VA: Defense Technical Information Center, January 2000. http://dx.doi.org/10.21236/ada381370.

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Yang, C. Y., and G. E. Wnek. Synthesis and Reactivity of Silyl-Ketene Acetal-Modified Polysiloxanes Preparation of Polysiloxanes with High Dielectric Constraints. Fort Belvoir, VA: Defense Technical Information Center, June 1991. http://dx.doi.org/10.21236/ada240754.

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Baltussen, Willy, Michiel van Galen, Katja Logatcheva, Machiel Reinders, Hanna Schebesta, Gerben Splinter, Gerben Doornewaard, et al. Positie primaire producent in de keten : samenwerking en prijsvorming. Wageningen: Wageningen Economic Research, 2018. http://dx.doi.org/10.18174/452740.

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de Koeijer, Tanja, Michiel van Galen, and Harry Luesink. Next Level Mestverwaarding : Organisatie en ontwikkeling van de keten. Den Haag: Wageningen Economic Research, 2020. http://dx.doi.org/10.18174/531980.

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Hoekstra, F. F., Y. de Valk, and B. Deetman. Visclusters in Nederland (nulmeting): omvang en afhankelijkheid voor de keten en toeleverende industrie van Noordzeevisserij : Impactanalyse beleidsbeslissingen op de keten van nederlandse visserijregio’s. Wageningen: Wageningen Economic Research, 2023. http://dx.doi.org/10.18174/590869.

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