463-51-4Relevant articles and documents
Thermochemistry of organic and heteroorganic species. Part VIII. Ketene and structurally related species
Golovin,Ponomarev,Takhistov
, p. 259 - 281 (2000)
Photoionization mass spectrometry was used to obtain the enthalpies of formation of CH2 = C = O ≤ -20.5 and -24.0 kcal mol-1 (from 3- phenylcyclobutanone and diketene, respectively), CH3C ≡ O+ ion 147.3 and 152.3 kcal mol-1 (from CH3COOCH = CH2 and CH3CONH2 molecules, respectively) and PhCH2C ≡ O+ 175.5 kcal mol-1 (from PhCH2COOMe molecules). The enthalpic shift procedure was applied for the estimation of the enthalpies of formation of ketene and related molecules. The following ΔH(f)0 values were found CH2 = C = O: -(22-25), CH2 = S = CH2 (67), CH2 = S = S (60), S = S = S (51), HC≡COH (10 kcal mol-1). The low value of ΔH0(f) (ketene) ? -23 kcal mol-1 as compared with the currently used value -11.4 kcal mol-1 was supported by the literature data, which have been revised in the present work. Using the new value for ketene's enthalpy of formation, those for ten substituted ketenes and HC ≡ CO (48.5 kcal mol- 1) free radical were obtained with the help of macroincremental schemes and introduction of correction terms. Computation of the enthalpies of formation of eight A = B = C molecules by MNDO, AM1, PM3 and MINDO/3 methods revealed that in most cases the latter gives the results closest to the experimental values or to those gained from the enthalpic shift procedure. The brief analysis of possible sources of errors in deducing the thermochemical values from appearance energies measurements has been made. Among those the isomerization processes occurring in molecular ions are considered the most important, which could lead to incorrect values of the enthalpies of formation of fragment ions, free radicals and molecules. With many examples it has been demonstrated that the application of the series of isodesmic reactions could be an effective tool for verifying, correcting and finding new values of the enthalpies of formation of neutral and ionized species. (C) 2000 Elsevier Science B.V.
UV-laser photochemistry of isoxazole isolated in a low-temperature matrix
Nunes, Claudio M.,Reva, Igor,Pinho E Melo, Teresa M. V. D.,Fausto, Rui
, p. 8723 - 8732,10 (2012)
The photochemistry of matrix-isolated isoxazole, induced by narrowband tunable UV-light, was investigated by infrared spectroscopy, with the aid of MP2/6-311++G(d,p) calculations. The isoxazole photoreaction starts to occur upon irradiation at λ = 240 nm, with the dominant pathway involving decomposition to ketene and hydrogen cyanide. However, upon irradiation at λ = 221 nm, in addition to this decomposition, isoxazole was also found to isomerize into several products: 2-formyl-2H-azirine, 3-formylketenimine, 3-hydroxypropenenitrile, imidoylketene, and 3-oxopropanenitrile. The structural and spectroscopic assignment of the different photoisomerization products was achieved by additional irradiation of the λ = 221 nm photolyzed matrix, using UV-light with λ ≥ 240 nm: (i) irradiation in the 330 ≥ λ ≥ 340 nm range induced direct transformation of 2-formyl-2H-azirine into 3-formylketenimine; (ii) irradiation with 310 ≥ λ ≥ 318 nm light induced the hitherto unobserved transformation of 3-formylketenimine into 3-hydroxypropenenitrile and imidoylketene; (iii) irradiation with λ = 280 nm light permits direct identification of 3-oxopropanenitrile; (iv) under λ = 240 nm irradiation, tautomerization of 3-hydroxypropenenitrile to 3-oxopropanenitrile is observed. On the basis of these findings, a detailed mechanistic proposal for isoxazole photochemistry is presented.
THIOACYLIUM IONS. GAS-PHASE ION-MOLECULE REACTIONS OF THIOIC AND DITHIOIC ACID DERIVATIVES.
Caserio,Kim
, p. 6896 - 6902 (1983)
Thioacylium ions CH//3CS** plus and C//2H//5CS** plus can be generated in the gas phase from acylium ions CH//3CO** plus and C//2H//5CO** plus and ethanethioic and propanethioic acids by using ion cyclotron resonance techniques. Similarly, CH//3CS** plus is formed in the ion chemistry of acetyl sulfide. Evidence to support the thioacylium structure for these ions was obtained from the nature of their reactions (proton transfer and thioacylation) and from the fact that they behave indistinguishably from thioacylium ions generated by EI cleavage of O-methyl ethanethioate and methyl ethanedithioate, CH//3C(S)XCH//3,X equals O,S. The heat of formation of CH//3CS** plus is estimated to be 210 kcal mol** minus **1. Mechanism studies with isotopically labeled reactants show that association of acylium ions with neutral S-acyl compounds leads to thioacylium ions by attack of RCO** plus at sulfur and to acylium ions (R prime CO** plus ) by attack at carbonyl oxygen.
A New Synthesis of Reactive Ketenes (Solutions)
Masters, Andrew P.,Sorensen, Ted S.,Ziegler, Tom
, p. 3558 - 3559 (1986)
Distilled solutions of reactive ketenes are conveniently prepared by the reaction of α-bromoacyl chlorides pentacarbonylmanganese anion.
Computationally Simple Model for Multiphoton-Induced Chemical Processes
McCluskey, Richard J.,Babu, S. V.
, p. 3210 - 3217 (1982)
A model for the multiphoton-induced decomposition of large polyatomic molecules that includes the effects of collisional deactivation is presented.Having only two adjustable parameters, the new model allows the time integral of the population of reactive energy states following the laser pulse to be computed very easily.The model is intended to describe experiments in which the bulk of reaction takes place after the laser pulse.It is particularly useful for describing decomposition through several competing reaction pathways.The model is applied to literature data on cyclobutanone.Very good agreement is obtained for the pressure dependence of the product ratio between the two decomposition channels and for the variation of the total decomposition with pressure for pressures less than about 0.6 torr.Reasons for the failure of the model at higher pressures are discussed.
Wilson,Kistiakowsky
, p. 2934 (1958)
Biocidal activity of the esterification products of polyfluoroalkyl alcohols and pentafluorophenol with resin acids
Nyanikova,Popova,Gaidukov,Shabrina,Vershilov
, p. 2738 - 2744 (2013)
Esterification products of polyfluoroalkyl alcohols and pentafluorophenol with resin acids were synthesized and tested for bactericidal activity against Bacillus mucilaginosus and Bacillus coagulans and fungicidal activity against Aspergillus niger, Aspergillus terreus, Alternaria alternata, Trichoderma viride, Rhizopus oryzae, Rhizopus nigricans, Mucor mucedo, Penicillium funiculosum, Penicillium ochro-chloron, and Botrytis cinerea.
Initial observations of ketene in flow reactor kinetic studies
Scire Jr., James J.,Klotz, Stephen D.,Dryer, Frederick L.
, p. 1011 - 1023 (2001)
Variable Pressure Flow Reactor (VPFR) experiments were conducted for ethene/methane mixtures utilizing both FTIR analyses of extracted gas samples and in situ line-of-sight far-UV absorption measurements. In situ observations of ketene prompted the re-evaluation of the presence of ketene in previous acetaldehyde oxidation and pyrolysis experiments in the VPFR. In these experiments only extractive sampling (with FTIR analysis) had been used and ketene had not been observed. In reconsidering the previously obtained FTIR spectra, ketene is shown to be not only present, but also present in levels on the order of other important acetaldehyde reaction intermediates, such as CH2O, H2, and C2H4. Through a comparison of the results of the in situ and extractive ketene diagnostics, it has been shown that significant losses of ketene can occur in sample handling and that the principal ketene loss mechanism appears to be surface dominated. It is likely that this difficulty in ketene sampling, common to many experimental systems, has led to the omission of important ketene pathways in many kinetic models. by Oldenbourg Wissenschaftsverlag, Muenchen.
Determination of the structural arrangements of ketene oligomers using NMR, FT-IR and ESI-MS
Swarnalatha,Sekaran
, p. 90 - 96 (2007)
Oligomer of ketene was synthesized using glycine as the source material in presence of free electron rich carbon through free radical mechanism. The structure and the compositions were determined by using 13C{1H} NMR and DEPT - 135 spectroscopy measurements. Two-dimensional heteronuclear (HETCOR) NMR spectroscopy was used to resolve the 1H NMR spectrum of the polymer. The NMR spectra reveal that the oligomers were generated as oligoester (OE), oligoketene (OK) and oligoacetal (OA) structural units. ESI-MS and ATR-FTIR also support these types of structural units in the crude polymer.
Cycloaddition of Ketene Radical Cation and Ethylene
Dass, Chhabil,Gross, Michael L.
, p. 5775 - 5780 (1984)
The reaction of the ketene radical cation and neutral ethylene has been investigated by using tandem mass spectrometry and Fourier transform mass spectrometry.The reaction was conducted at high pressures (150-500 mtorr) in the presence of an inert bath gas which permitted collisional stabilization and isolation of the adduct for study by collisionally activated dissociation (CAD) and metastable ion spectroscopy.The structure of the adduct was established to be that of the cyclobutanone radical cation.Thus, the mechanism of the reaction is a facile cycloaddition across the carbon-carbon double bond of the ketene radical cation.
Highly active PtAu nanowire networks for formic acid oxidation
Xiao, Meiling,Li, Songtao,Zhu, Jianbing,Li, Kui,Liu, Changpeng,Xing, Wei
, p. 1123 - 1128 (2014)
The PtAu alloy nanowire networks (NWNs) were synthesized directly in an aqueous solution using Triton X-114 as the structure-inducing agent. The NMNs formed based on the oriented-attachment growth mechanism, and they exhibited dramatically enhanced electr
Photodissociation dynamics of ketene at 157.6 nm
Lu, I-Chung,Lee, Shih-Huang,Lee, Yuan T.,Yang, Xueming
, (2006)
Photodissociation dynamics of ketene at 157.6 nm has been investigated using the photofragment translational spectroscopic technique based on photoionization detection using vacuum-ultraviolet synchrotron radiation. Three dissociation channels have been observed: C H2 +CO, CH+HCO, and HCCO+H. The product translational energy distributions and angular anisotropy parameters were measured for all three observed dissociation channels, and the relative branching ratios for different channels were also estimated. The experimental results show that the direct C-C bond cleavage (C H2 +CO) is the dominant channel, while H migration and elimination channels are very minor. The results in this work show that direct dissociation on excited electronic state is much more significant than the indirect dissociation via the ground state in the ketene photodissociation at 157.6 nm.
The ultraviolet photochemistry of condensed-phase acetyl chloride
Rowland, Brad,Hess, Wayne P.
, p. 574 - 580 (1996)
Ultraviolet (UV) irradiation of amorphous and crystalline samples of solid acetyl chloride produces metastable HC1 · ketene complexes in a 1:1 ratio following S1 photoexcitation. The HC1 · ketene complex is the only product observed following UV irradiation of either amorphous or crystalline samples. The condensed-phase reaction mechanism contrasts starkly with that of the gas phase mechanism that produces Cl and CH3CO radicals by prompt photolysis, followed by dissociation of internally excited CH3CO to form CO and CH3 in a non-concerted process.
Evidence for sequential reactions in the CO2 laser induced multiphoton dissociation of acetic anhydride and acetic acid
Grimley, A.J.,Stephenson, J.C.
, p. 447 - 452 (1981)
The CO2 laser induced multiphoton dissociation of acetic acid and acetic anhydride has been investigated.We have observed the prompt formation of 1CH2 and OH by laser excited fluorescence and determined their nascent rotational energy distributions.The rotational energy of each product was the same, regardless of which starting material was photolyzed.This observation leads us to propose a mechanism in which both the 1CH2 and OH are formed by sequential up-pumping of molecular intermediates.We have also determined the yield versus fluence curves for both the (0,0,0) levels and a(0,1,0) levels of 1CH2.The relative yields of these two levels are found to change as a function of intensity.
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Hurd,Tallyn
, p. 1782 (1925)
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1,1-Ethenediol: The Long Elusive Enol of Acetic Acid
Eckhardt, André K.,Mardyukov, Artur,Schreiner, Peter R.
, p. 5577 - 5580 (2020/02/20)
We present the first spectroscopic identification of hitherto unknown 1,1-ethenediol, the enol tautomer of acetic acid. The title compound was generated in the gas phase through flash vacuum pyrolysis of malonic acid at 400 °C. The pyrolysis products were
