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.
APPLICATIONS OF THE EQUIVALENT CORES APPROXIMATION. THE DETERMINATION OF PROTON AFFINITIES AND ISOCYANIDE-TO-NITRILE ISOMERIZATION ENERGIES FROM CORE BINDING ENERGIES.
Beach,Eyermann,Smit,Xiang,Xiang
, p. 536 - 539 (1984)
Core binding energies were determined for the following gas-phase molecules: CH//2CCH//2, CH//2CO, BH//3CO, HNCO, CH//3CN, CH//3NC, NH//2CH, t-BuNC, and C//6H//5NC. By use of the equivalent cores approximation, these data and data from the literature were used to calculate the proton affinities of N//2O, CO//2, HCCF, NCF, NH//2CH, CH//2N//2, HNCO, CH//2CO, HN//3, CH//3NC, and CH//3CN with an estimated accuracy of plus or minus 7 kcal mol** minus **1. By a similar method, the isocyanide-to-nitrile isomerization energies for CH//3NC, t-BuNC, and C//6H//5NC were calculated to be minus 30, minus 27 and minus 28 kcal mol** minus **1, respectively.
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.
Reactivities of ketene ligands on polymetallic systems
Akita, Munetaka,Andoh, Hitoshi,Mitani, Osamu,Oku, Tomoharu,Moro-Oka, Yoshihiko
, p. 107 - 116 (1989)
Heterobimetallic μ-η2-(C,C)-[M1-CH2CO-M2] and trimetallic μ3-η3-(C,C,O)-ketene complexes [M1-CH2(C$UNKO → M3)-M2] (M1 = Fe; M2/s
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.
Kinetic Investigation of the + H -> CH(X2II) + H2 Reaction in the Temperature Range 400 K < T < 1000 K
Devriendt, K.,Van Poppel, M.,Boullart, W.,Peeters, J.
, p. 16953 - 16959 (1995)
The + H -> CH(X2II) + H2 reaction (1) was investigated in CH2CO/O systems (T = 400, 500, 650, and 950 K, p = 2 Torr) as well as in C2H2/O systems (T=590 and 890 K, p = 4 Torr) using discharge-flow/molecular beam sampling mass spectrometry techniques (D-F/MBMS).The first rate coefficient data at temperatures intermediate between room and flame temperature are presented.The + H rate constant was measured relative to the well-known + O = (1.3 +/- 0.3) x 1E-10 cm3 molecule-1 s-1 from the change of the quasi-steady state CH2 concentration upon varying the / ratio at given CH2 formation rate.In the temperature range of interest, the k1 coefficient was found to exhibit a clear-cut negative temperature dependence.The following k1 was obtained: (i) using the CH2CO + O reaction as CH2 source, (2.93 +/- 0.80) x 1E-10 at 400 K, (2.05 +/- 0.57) x 1E-10 at 500 K, (1.22 +/- 0.31) x 1E-10 at 650 K, and (1.18 +/- 0.32) x 1E-10 at 950 K; (ii) using the C2H2 + O system as CH2 source, (1.90 +/- 0.58) x 1E-10 at 590 K and (1.12 +/- 0.36) x 1E-10 at 890 K (k in cm3 molecule-1 s-1; 95percent cofidence intervals, including possible systematic errors).The data obtained with the two CH2 sources are in good mutual agreement.The decrease of k1 with temperature is in accord with literature k1 data at room temperature on one side and in the 1500-2500 K range on the other.However, the observed temperature dependence in the 300-1000 K range is much less steep than predicted by the recommended k1(T) expression in a recent evaluation.An equation that fits all available data reasonably well is k1 = 3.8 x 1E-10 exp cm3 molecule-1 s-1, for T = 300-2500 K.
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.
Substitution Reactions in the Pyrolysis of Acetone Revealed through a Modeling, Experiment, Theory Paradigm
Zaleski, Daniel P.,Sivaramakrishnan, Raghu,Weller, Hailey R.,Seifert, Nathan A.,Bross, David H.,Ruscic, Branko,Moore, Kevin B.,Elliott, Sarah N.,Copan, Andreas V.,Harding, Lawrence B.,Klippenstein, Stephen J.,Field, Robert W.,Prozument, Kirill
, p. 3124 - 3142 (2021)
The development of high-fidelity mechanisms for chemically reactive systems is a challenging process that requires the compilation of rate descriptions for a large and somewhat ill-defined set of reactions. The present unified combination of modeling, experiment, and theory provides a paradigm for improving such mechanism development efforts. Here we combine broadband rotational spectroscopy with detailed chemical modeling based on rate constants obtained from automated ab initio transition state theory-based master equation calculations and high-level thermochemical parametrizations. Broadband rotational spectroscopy offers quantitative and isomer-specific detection by which branching ratios of polar reaction products may be obtained. Using this technique, we observe and characterize products arising from H atom substitution reactions in the flash pyrolysis of acetone (CH3C(O)CH3) at a nominal temperature of 1800 K. The major product observed is ketene (CH2CO). Minor products identified include acetaldehyde (CH3CHO), propyne (CH3CCH), propene (CH2CHCH3), and water (HDO). Literature mechanisms for the pyrolysis of acetone do not adequately describe the minor products. The inclusion of a variety of substitution reactions, with rate constants and thermochemistry obtained from automated ab initio kinetics predictions and Active Thermochemical Tables analyses, demonstrates an important role for such processes. The pathway to acetaldehyde is shown to be a direct result of substitution of acetone's methyl group by a free H atom, while propene formation arises from OH substitution in the enol form of acetone by a free H atom.
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.
