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1.
Koch R Finnerty JJ Bruhn T Borget F Wentrup C 《The journal of physical chemistry. A》2008,112(38):8999-9004
The complex reaction of thermally generated iminopropadienones with amines in the gas phase and upon matrix deposition and its varying product composition is investigated using density functional theory. In the high energy gas phase addition a single amine molecule reacts readily with iminopropadienone with the decisive step being a 1,3-hydrogen shift and activation barriers of at least 100 kJ/mol. In accordance with the experiment, the formation of ketenes is favored. In the condensed phase of an amine matrix, the utilization of amine dimers both as reagents and as explicit solvents lowers the activation energy required to a feasible 20-30 kJ/mol and predicts ketenimines as the main products, as observed experimentally. 相似文献
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Conclusions The reaction of trinitromethane with ketene (prepared in a ketene lamp) proceeds with the formation of 1,1,1-trinitro-tert-butyl acetate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 674–675, March, 1970. 相似文献
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[reaction: see text] N-[2-(Alkyl- or arylthio)carbonyl]phenyl ketenimines undergo cyclization under mild thermal conditions to afford 2-alkyl(aryl)thio-3H-quinolin-4-ones by means of the 1,5-migration of the alkyl(aryl)thio group from the carbonyl carbon to the central carbon atom of the ketenimine fragment followed by the 6pi-electrocyclization of the resulting vinyliminoketene. These 1,5-migration and electrocyclization processes occur via transition states whose pseudopericyclic characteristics have been established on the basis of their magnetic properties, geometries, and NBO analyses. 相似文献
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Guennoun Z Couturier-Tamburelli I Combes S Aycard JP Piétri N 《The journal of physical chemistry. A》2005,109(51):11733-11741
Irradiations at lambda > 180 nm and lambda > 230 nm of CH3COCN (CD3COCN) trapped in an argon matrix at 10 K have been performed and monitored by Fourier transform infrared spectroscopy. For both wavelengths, the first photoreaction product is acetyl isocyanide. At lambda > 180 nm acetonitrile and methyl isocyanide are obtained as final products. They are formed by photolysis of acetyl isocyanide and acetyl cyanide, respectively. Unstable intermediates, such as ketene:HCN and ketene:HNC complexes, H2CNCH zwitterion, and H2C2NH keteneimine, not observed in the gas phase, are trapped and identified at our experimental temperature. The complexes have an L-shaped structure with a hydrogen bond between the oxygen atom of ketene and the hydrogen atom of HCN or HNC. A pathway process is proposed and compared with the ones determined in the ground state by ab initio calculations. 相似文献
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The reaction of 3-methyl-2-methylene-1,3-oxazolidine ( 1a ) and phenylisothiocyanate (PhNCS) gives 3-methyl-2-(phenylthiocarbamoyl)methylene-1,3-oxazolidine ( 3 ) whereas that of 2-isopropylidene-3-methyl-1,3-oxazolidine ( 1b ) and PhNCS gives 1:1 alternating copolymers. It is assumed that the reaction of 1b and PhNCS forms a zwitterionic intermediate ( 2b ), followed by the successive combination of 2b to give 1:1 alternating copolymers 4 and/or 5 . Consequently, it was demonstrated that the copolymerization of 1b and PhNCS proceeds via a zwitterionic mechanism with complete ring-opening to afford the 1:1 alternating copolymer 5 . 相似文献
6.
Syroeshkina Yu. S. Petukhova V. Yu. Kachala V. V. Nelyubina Yu. V. Makhova N. N. 《Russian Chemical Bulletin》2010,59(7):1433-1441
A reaction of aryl ketenes with 1-arylmethylidenepyrazolidin-1-azomethine imines, generated by the diaziridine ring opening
in 6-aryl-1,5-diazabicyclo[3.1.0]hexanes catalyzed with Et2O·BF3, leads to 1,2-bis(phenylacetyl)pyrazolidine, 2-arylacetyl-1-arylidenepyrazolidin-1-ium
chlorides, or a representative of 1,5-diazabicyclo[3.3.0]octan-2-ones, viz., 4-(4-eth-oxyphenyl)-3,3-diphenyl-1,5-diazabicyclo[3.3.0]octan-2-one, depending on the reaction conditions and the structure
of the starting compounds. A mechanism suggested earlier for the transformation of 1,5-diazabicyclo[3.1.0]hexanes in the reaction
with ketenes was confirmed. 相似文献
7.
Petar Y. Petrov Christo M. Angelov Robert McDonald Alexi Alexiev Ronald G. Cavell 《Heteroatom Chemistry》2010,21(3):196-202
Isothiocyanates react with Me2P‐N(SiMe3)2 with elimination of (Me3Si)2S to give new structurally characterized heterocyclic diazaphosphole derivatives, and in one case the intermediate zwitterionic compound was isolated and structurally characterized. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:196–202, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20595 相似文献
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Leaving groups such as carboxylate, thiolate, and phenolate are expelled via zwitterionic intermediates produced upon photochemical electrocyclic ring closure of benzothiophene carboxanilides in the triplet excited state. Chemical yields generally exceed 90%, while quantum yields vary with basicity of the released leaving group. 相似文献
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The intermolecular interaction energy for reacting systems in singlet, triplet and doublet states was partitioned by the perturbation expansion method into the chemically meaningful five interaction terms: the Coulomb, exchange-repulsion, induction, dispersion, and charge-transfer energies. In the local ZDO approximation, these energy terms were evaluated for the dimerization of methylenes (1,3CH2), the additions of carbenes (1,3CH2 and1,3CF2) as well as amino radicals (2NH2 and2NF2) toward ethylene, and the hydrogen abstractions by methylenes (1,3CH2), nitrene (3NH), and hydroxyl radical (2OH) from methane. It has been found that the reaction path is much influenced by the spinmultiplicity, and that the charge-transfer and exchange-repulsion terms play a dominant role in determining the course of reactions. 相似文献
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Elizabeth Dyer Eugene Sincich 《Journal of polymer science. Part A, Polymer chemistry》1973,11(6):1249-1260
Diphenyl-, phenylethyl, and phenylmethylketene have been copolymerized with phenyl isocyanate by use of sodium naphthalene in dimethylformamide (DMF) at ?45°C. Reactivity ratios of phenyl isocyanate (r2) with diphenylketene (r1) were r1 = 0.10, r2 = 0.29; with phenylethylketene (r1) were r1 = 1.6, r2 = 0.10; and with phenyl methyl ketene (r1) were r1 = 4.8, r2 = 0.02. The same initiator and solvent system were used for homopolymerization of phenylethylketene and copolymerization with m-chloro-, p-chloro-, p-methoxy-, and m-methoxyphenyl isocyanate as well as with phenyl isocyanate. Molecular weights ranged from 1740 to 4000. The effect of substituents on the order of isocyanate incorporation into the copolymer was m-Cl = p-Cl > m-MeO > H > p-MeO. Phenylethylketene was also copolymerized with m-methoxyphenyl, p-methoxyphenyl, and p-tolyl isocyanate in tetrahydrofuran (THF) at ?78°C. Molecular weights ranged from 2800 to 10,500. The least reactive isocyanate was incorporated into the copolymer to a greater extent in this solvent than in the more polar DMF. DTA showed the presence of crystallinity only in polymers of high isocyanate content. The ketenes copolymerized less readily with alkyl isocyanates, such as ethyl, n-butyl, n-hexyl, and cyclohexyl isocyanate, than with the aromatic isocyanates when sodium naphthalene was used in either DMF or THF. 相似文献
13.
The cycloaddition of ketenes with cyclic carbodiimides yields β-lactams in good to excellent yields. The cycloaddition of equal molar amounts of diphenyl-, phenylethyl- and phenylketenes with cyclic carbodiimides produced a 1:1 cycloaddition product, the expected β-lactams. However, the cycloaddition of a 2:1 molar ratio of diphenyl- and phenylketenes with 1,3-diazacycloocta-1,2-diene respectively, gave the 2:1 cycloadducts, the tricyclodi-β-lactams. The cycloaddition of methylchloro- and dichloroketenes yielded β-lactams that were very susceptible to hydrolysis to the N-substituted cycloureas. A trapping experiment suggests that these reactions proceed through a stabilized dipolar intermediate. 相似文献
14.
Jia J Sarker M Steinmetz MG Shukla R Rathore R 《The Journal of organic chemistry》2008,73(22):8867-8879
Methacrylanilides, ArN(CH3)COC(CH2LG)=CH2, with allylic leaving groups (LG(-) = BocAla, PhCO2(-), PhCH2CO2(-), PhO(-)) undergo photochemical electrocyclic ring closure to produce a zwitterionic intermediate. Further reaction of the intermediate results in expulsion of the leaving group to give an alpha-methylene lactam as the major product. In addition, a lactam product that retains the leaving group is formed via a 1,5-H shift in the intermediate. Elimination of the leaving group is generally preferred, even for LG(-) = PhO(-), although in benzene as the solvent the lactam retaining the phenolate group becomes the sole photoproduct. The electrocyclic ring closure occurs in the singlet excited-state for the para-COPh-substituted anilide derivative and is not quenched by 0.15 M piperylene or 0.01 M sodium 2-naphthalenesulfonate (2-NPS) as triplet quenchers. Comparable concentrations of 2-NPS strongly quench the transient absorption of the triplet excited state observed at 450-700 nm according to laser flash photolysis experiments. In aqueous media, quantum yields for total products are insensitive to leaving group ability, and Phi(tot)(para-CO2CH3) = 0.04-0.06 at 310 nm and Phi(tot)(para-COPh) = 0.08-0.1 at 365 nm, for which Phi(isc) = 0.15. 相似文献
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[reaction: see text] At 50 degrees C, dimethyl dicyanofumarate and maleate react with 2 equiv of dimethoxycarbene to generate the products shown. 相似文献
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M. B. Gazizov R. A. Khairullin R. F. Karimova 《Russian Journal of General Chemistry》2014,84(1):75-81
Primary intermediates of P(III) chlorides reaction with aldehydes have been converted into the corresponding phosphates by treating with oxidants: dimethylsulfoxide and tert-butyl hypochlorite. In reactions of the intermediates with chlorinating agents (PCl5 and Cl2) the oxidation products are formed (due to the ligand exchange at quasiphosphonium center) along with the expected P(IV) acid chlorides. 相似文献
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I. S. Kolomnikov Yu. D. Koreshkov T. S. Lobeeva M. E. Vol'pin 《Russian Chemical Bulletin》1972,21(5):1132-1133
Conclusions We obtained the complexes of (Ph3P)3PtO2 with diphenylketene, phenyl isocyanate, carbon suboxide. PhNCS and PhNSO, and also the complex: (Ph3P)2RhCl·2PhNCO.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1181–1183, May, 1972. 相似文献