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Cas Database

463-51-4

463-51-4

Identification

  • Product Name:Ethenone

  • CAS Number: 463-51-4

  • EINECS:207-336-9

  • Molecular Weight:42.0373

  • Molecular Formula: C2H2O

  • HS Code:2914190090

  • Mol File:463-51-4.mol

Synonyms:Ketene(8CI);Carbomethene;

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Safety information and MSDS view more

  • Signal Word:Danger

  • Hazard Statement:H220 Extremely flammable gasH315 Causes skin irritation H318 Causes serious eye damage H330 Fatal if inhaled H335 May cause respiratory irritation

  • First-aid measures: General adviceConsult a physician. Show this safety data sheet to the doctor in attendance.If inhaled Fresh air, rest. Half-upright position. Artificial respiration may be needed. Refer for medical attention. In case of skin contact Remove contaminated clothes. Rinse skin with plenty of water or shower. In case of eye contact First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention. If swallowed Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician. Exposure Routes: inhalation, skin and/or eye contact Symptoms: Irritation eyes, skin, nose, throat, respiratory system; pulmonary edema Target Organs: Eyes, skin, respiratory system (NIOSH, 2016)

  • Fire-fighting measures: Suitable extinguishing media Excerpt from ERG Guide 131P [Flammable Liquids - Toxic]: CAUTION: All these products have a very low flash point: Use of water spray when fighting fire may be inefficient. SMALL FIRE: Dry chemical, CO2, water spray or alcohol-resistant foam. LARGE FIRE: Water spray, fog or alcohol-resistant foam. Move containers from fire area if you can do it without risk. Dike fire-control water for later disposal; do not scatter the material. Use water spray or fog; do not use straight streams. FIRE INVOLVING TANKS OR CAR/TRAILER LOADS: Fight fire from maximum distance or use unmanned hose holders or monitor nozzles. Cool containers with flooding quantities of water until well after fire is out. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. For massive fire, use unmanned hose holders or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2016) Excerpt from ERG Guide 131P [Flammable Liquids - Toxic]: HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion and poison hazard indoors, outdoors or in sewers. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water. (ERG, 2016) Wear self-contained breathing apparatus for firefighting if necessary.

  • Accidental release measures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapours, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust. For personal protection see section 8. Evacuate danger area! Consult an expert! Ventilation. Personal protection: gas-tight chemical protection suit including self-contained breathing apparatus. PERSONS NOT WEARING PROTECTIVE EQUIPMENT AND CLOTHING SHOULD BE RESTRICTED FROM AREAS OF LEAKS UNTIL CLEANUP HAS BEEN COMPLETED. IF KETENE IS LEAKED, THE FOLLOWING STEPS SHOULD BE TAKEN: 1. REMOVE ALL IGNITION SOURCES. 2. VENTILATE THE AREA OF LEAK. 3. STOP FLOW OF GAS. DISPOSAL METHODS: KETENE MAY BE DISPOSED OF BY BURNING AT A SAFE LOCATION OR IN A SUITABLE COMBUSTION CHAMBER.

  • Handling and storage: Avoid contact with skin and eyes. Avoid formation of dust and aerosols. Avoid exposure - obtain special instructions before use.Provide appropriate exhaust ventilation at places where dust is formed. For precautions see section 2.2. The substance cannot be stored or shipped....CANNOT BE...STORED IN A GASEOUS STATE.

  • Exposure controls/personal protection:Occupational Exposure limit valuesRecommended Exposure Limit: 10 Hr Time-Weighted Avg: 0.5 ppm (0.9 mg/cu m).Recommended Exposure Limit: 15 Min Short-Term Exposure Limit: 1.5 ppm (3 mg/cu m).Biological limit values Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday. Eye/face protection Safety glasses with side-shields conforming to EN166. Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU). Skin protection Wear impervious clothing. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace. Handle with gloves. Gloves must be inspected prior to use. Use proper glove removal technique(without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands. The selected protective gloves have to satisfy the specifications of EU Directive 89/686/EEC and the standard EN 374 derived from it. Respiratory protection Wear dust mask when handling large quantities. Thermal hazards

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Relevant articles and documentsAll total 153 Articles be found

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.

-

Rice,Vollrath

, (1930)

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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.

Wilson,Kistiakowsky

, p. 2934 (1958)

Infrared Spectrum and Photochemistry of Methoxychlorocarbene

Sheridan, Robert S.,Kasselmayer, Mark A.

, p. 436 - 437 (1984)

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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.

Thermokinetic Determination of Gas-Phase Basicities. Application to Ketene, Methylketene, and Formaldimine

Bouchoux, Guy,Salpin, Jean-Yves

, p. 16555 - 16560 (1996)

Rate constants have been determined for proton transfer reactions of the type (1+) + B ->/(1+), where M is ketene, methylketene, and formaldimine and B is a reference base.A quantitative relationship between the rate constant and the free energy (or enthalpy) of the reaction allows the determination of the gas-phase basicity, GB, (or proton affinity, PA) of M.This thermokinetic method gives results comparable to that obtained from equilibrium constant measurements.The values derived for ketene, methylketene, and formaldimine follow: GB(ketene) = 788 +/- 3 kJ/mol, PA(ketene) = 817 +/- 3 kJ/mol; GB(methylketene) = 809 +/- 3 kJ/mol, PA(methylketene) = 842 +/- 3 kJ/mol; GB(formaldimine) = 830 +/- 3 kJ/mol and PA(formaldimine) = 860 +/- 5 kJ/mol.Heats of formation of methylketene and of formaldimine that may be deduced from a combination of these results with literature data are as follows: ΔHf0300(CH3CHCO) = -97 +/- 5 kJ/mol and ΔHf0300(CH2=NH) = 75 +/- 5 kJ/mol.

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.

Preparation and characterization of the enol of acetamide: 1-aminoethenol, a high-energy prebiotic molecule

Keul, Felix,Mardyukov, Artur,Schreiner, Peter R.

, p. 12358 - 12363 (2020)

Amide tautomers, which constitute the higher-energy amide bond linkage, not only are key for a variety of biological but also prebiotic processes. In this work, we present the gas-phase synthesis of 1-aminoethenol, the higher-energy tautomer of acetamide, that has not been spectroscopically identified to date. The title compound was prepared by flash vacuum pyrolysis of malonamic acid and was characterized employing matrix isolation infrared as well as ultraviolet/visible spectroscopy. Coupled-cluster computations at the AE-CCSD(T)/cc-pVTZ level of theory support the spectroscopic assignments. Upon photolysis at λ > 270 nm, the enol rearranges to acetamide as well as ketene and ammonia. As the latter two are even higher in energy, they constitute viable starting materials for formation of the title compound. This journal is

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.

A Comparative Rate Method for the Study of Unimolecular Falloff Behavior

Braun, Walter,McNesby, J. R.,Scheer, Milton D.

, p. 1846 - 1850 (1984)

A comparative method was applied to a high-temperature fast-flow reactor to determine relative kinetic parameters for the two-channel decomposition of cyclobutanone in the falloff region.The applicability of this method to such nonthermally equilibrated systems was assessed and found to be generally useful over a wide range of conditions.The measurements could, therefore, be used as a quantitative diagnostic tool for sensing unimolecular falloff behavior in a number of heat bath gases.A simple stepladder collisional activation-deactivation model was used to determine the energy transferred per collision.The values obtained for the heat bath gases He, Ar, SiF4, and SF6 were 3.0, 2.0, 3.5, and 4.0 kcal/mol, respectively.These are small multiples of RT and very small fractions of the activation energy, indicating that weak collisions must be a dominant feature of reaction types represented by the decomposition of cyclobutanone.

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.

The vinylketene-acylallene rearrangement: Theory and experiment

Bibas, Herve,Wong, Ming Wah,Wentrup, Curt

, p. 237 - 248 (1997)

Alkoxyviniyketenes 4 are generated by flash vacuum thermolysis (FVT) or photolysis of 3-alkoxycyclobutenones 3. The thermal interconversion of 4 and allene carboxylic acid esters 5 under FVT conditions is demonstrated by Ar matrix FTIR spectroscopy. In addition, ethoxyvinylketene 4b undergoes thermal elimination of ethene with formation of s-cis-and s-trans-acetylketene (8). An analogous aminovinylketene-to-allenecarboxymide conversion is observed on FVT of 3-dimethylaminocyclobutenone 3e. A facile 1,3-chlorine migration in 2,3-butadienoyl chloride (5d) is also reported. Consistent with the experimental observations, 1,3-methoxy, 1,3-chloro, and 1,3-dimethylamino migrations in vinylketene are calculated (G2(MP2,SVP) level) to have moderate barriers of 169, 157, and 129 kJmol-1, respectively, significantly less than the corresponding 1,3-H shift barrier (273 kJ mol-1). The stabilization of the four-center transition structures is rationalized in terms of the donor acceptor interaction between the lone pair electrons of the migrating donor substituent and the vacant central carbon p-orbital of the ketene LUMO. The predicted migratory aptitude in the series of substituted vinylketenes. R-C(=CH2)-CH=C=O, is in the order N(CH3)2>SCH3>SH>Cl>NH2>OCH3>OH>F>H>CH3, and correlates well with the electron-donating ability of the R group.

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

-

Dunbar,Bolstadt

, p. 219 (1944)

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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.

Gas Phase Chemistry of CH2.-

DePuy, Charles H.,Barlow, Stephan E.,Doren, Jane M. Van,Roberts, Chris R.,Bierbaum, Veronica M.

, p. 4414 - 4415 (1987)

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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.

The Elusive Ketene (H2CCO) Channel in the Infrared Multiphoton Dissociation of Solid 1,3,5-Trinitro-1,3,5-Triazinane (RDX)

Chang, Agnes H. H.,Chen, Yue-Lin,Kaiser, Ralf I.,La Jeunesse, Jesse,Mebel, Alexander M.,Singh, Santosh K.,Son, Steven F.,Sun, Bing-Jian,Vuppuluri, Vasant

, (2020)

Understanding of the fundamental mechanisms involved in the decomposition of 1,3,5-trinitro-1,3,5-triazinane (RDX) still represents a major challenge for the energetic materials and physical (organic) chemistry communities mainly because multiple competing dissociation channels are likely involved and previous detection methods of the products are not isomer selective. In this study we exploited a microsecond pulsed infrared laser to decompose thin RDX films at 5 K under mild conditions to limit the fragmentation channels. The subliming decomposition products during the temperature programed desorption phase are detected using isomer selective single photoionization time-of-flight mass spectrometry (PI-ReTOF-MS). This technique enables us to assign a product signal at m/z=42 to ketene (H2CCO), but not to diazomethane (H2CNN; 42 amu) as speculated previously. Electronic structure calculations support our experimental observations and unravel the decomposition mechanisms of RDX leading eventually to the elusive ketene (H2CCO) via an exotic, four-membered ring intermediate. This study highlights the necessity to exploit isomer-selective detection schemes to probe the true decomposition products of nitramine-based energetic materials.

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.

Doppler-resolved spectroscopy as an assignment tool in the spectrum of singlet methylene

Hall, Gregory E.,Komissarov, Anatoly V.,Sears, Trevor J.

, p. 7922 - 7927 (2004)

New spectra of methylene, CH2, in the near-infrared have been obtained following 308 nm photolysis of ketene, CH2CO. Nascent photofragment Doppler spectra and thermalization kinetics vary systematically with the energy of the absorbing level, providing additional information to support or refute spectroscopic assignments made on the basis of the frequency measurements and combination differences. New assignments in the 10800 cm -1 region extend to higher rotational levels than before and provide new spectroscopic term values for some CH2 a1A 1 state levels. The number and intensity distribution of unassigned lines in the spectrum is consistent with the expected transitions from vibrationally excited and high rotational levels of the a1A1 state and transitions due to 13CH2 in natural abundance, and does not require a significant contribution from additional transitions arising from triplet-state perturbations.

-

Hurd,Tallyn

, p. 1782 (1925)

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Catalytic Dehydration of Acetic Acid on a Graphitized Platinum Surface

Vajo, J. J.,Sun, Y.-K.,Weinberg, W. H.

, p. 1153 - 1158 (1987)

Absolute reaction rates have been measured in a continuous flow microreactor for the steady-state, catalytic dehydration of acetic acid to ketene at pressures between 8 x 10-7 and 7 x 10-4 Torr and temperature between 500 and 800 K.The catalyst was a polycrystalline platinum wire containing a approximately a monolayer of graphitic carbon.At 675 K or above, for the entire range of pressures studied, the order of the dehydration reaction is unity with respect to acetic acid pressure.In this regime, the apparent activation energy is 1 +/= 1 kcal/mol, and the extrapolated probability at 1/T = 0 (2.5-10) x 10-4.Under these conditions,the rate of dehydration is determined by a competition between the rates of desorption and surface reaction of molecularly adsorbed acetic acid.For temperatures below 540 K and pressures of 3.5 x 10-4 Torr and above, the reaction rate is independent of acetic acid pressure, and the apparent activation energy is 27 +/= 2 kcal/mol.Under these conditions, the rate of decomposition of a surface intermediate controls the rate of reaction.A mechanistic model is developed and discussed which described accurately both the temperature and the pressure dependence of the rate of dehydration.

Structural, spectroscopic, and photochemical study of ethyl propiolate isolated in cryogenic argon and nitrogen matrices

Fausto, Rui,Lopes, S.,Nikitin, T.

, (2020/07/15)

Ethyl propiolate (HC ≡ CCOOCH2CH3, EP) was studied experimentally by infrared spectroscopy in argon and nitrogen cryomatrices (15 K) and by quantum chemical calculations (at the DFT(B3LYP) and MP2 levels of theory). Calculations predict the existence of four conformers: two low-energy conformers (I and II) possessing the carboxylic moiety in the cis configuration (O=C–O–C dihedral equal to ~0°) and two higher-energy trans forms (O=C–O–C dihedral equal to ~180°; III and IV). The conformation of the ethyl ester group within each pair of conformers is either anti (C–O–C–C equal to 180°; in conformers I and III) or gauche (C–O–C–C equal to ±86.6° in II, and ± 92.5° in IV). The two low-energy cis conformers (I and II) were predicted to differ in energy by less than 2.5 kJ mol?1 and were shown to be present in the studied cryogenic matrices. Characteristic bands for each one of these conformers were identified in the infrared spectra of the matrix-isolated compound and assigned taking into account the results of normal coordinate analysis, which used the geometries and harmonic force constants obtained in the DFT calculations. The two trans conformers (III and IV) were estimated to be 17.5 kJ mol?1 higher in energy than the conformational ground state (form I) and were not observed experimentally. The unimolecular photochemistry of matrix-isolated EP (in N2 matrix) was also investigated. In situ irradiation with UV light (λ > 235 nm) leads mainly to decarbonylation of the compound, with generation of ethoxyethyne, which in a subsequent photoreaction generates ketene (plus ethene).

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

Process route upstream and downstream products

Process route

methyl (trimethylsilyl)acetate
2916-76-9

methyl (trimethylsilyl)acetate

Ketene
463-51-4

Ketene

Trimethylmethoxysilane
1825-61-2

Trimethylmethoxysilane

Conditions
Conditions Yield
at 326.9 ℃; Rate constant; Kinetics; gas-phase pyrolysis; E(excit.);
trimethylsilanyl-acetic acid ethyl ester
4071-88-9

trimethylsilanyl-acetic acid ethyl ester

Ketene
463-51-4

Ketene

ethyl trimethylsilyl ether
1825-62-3

ethyl trimethylsilyl ether

Conditions
Conditions Yield
at 360 ℃; Rate constant; other temperature;
at 326.9 ℃; Rate constant; Kinetics; gas-phase pyrolysis; E(excit.);
ethyl α-(diphenylmethylsilyl)acetate
13950-57-7

ethyl α-(diphenylmethylsilyl)acetate

Ketene
463-51-4

Ketene

ethoxy(methyl)(diphenyl)silane
1825-59-8

ethoxy(methyl)(diphenyl)silane

Conditions
Conditions Yield
at 360.1 ℃; Rate constant; other temperature;
ethyl [2-(dimethylphenyl)silyl]ethanoate
13950-56-6

ethyl [2-(dimethylphenyl)silyl]ethanoate

Ketene
463-51-4

Ketene

dimethyl(ethoxy)phenylsilane
1825-58-7

dimethyl(ethoxy)phenylsilane

Conditions
Conditions Yield
at 360 ℃; Rate constant; other temperature;
hexane
110-54-3

hexane

2-ethyltetrahydrofuran
1003-30-1,123931-62-4

2-ethyltetrahydrofuran

2-ethyl-4-methyloxetane
5410-21-9

2-ethyl-4-methyloxetane

2,5-dimethyltetrahydrofuran
1003-38-9

2,5-dimethyltetrahydrofuran

2-methyloxane
10141-72-7

2-methyloxane

1,2-Epoxyhexane
1436-34-6

1,2-Epoxyhexane

2,3-epoxyhexane
1192-32-1

2,3-epoxyhexane

2-propyl-oxetane
4468-64-8

2-propyl-oxetane

methanol
67-56-1

methanol

Ketene
463-51-4

Ketene

ethane
74-84-0

ethane

ethene
74-85-1

ethene

1,2-propanediene
463-49-0

1,2-propanediene

acetaldehyde
75-07-0,9002-91-9

acetaldehyde

acetic acid
64-19-7,77671-22-8

acetic acid

propionic acid
802294-64-0,79-09-4

propionic acid

methyloxirane
75-56-9,16033-71-9

methyloxirane

prop-1-yne
74-99-7

prop-1-yne

Conditions
Conditions Yield
With oxygen; at 376.84 ℃; for 0.000555556h; under 795.08 Torr; Temperature; Inert atmosphere;
1,4-diphenyl-azetidin-2-one
13474-22-1

1,4-diphenyl-azetidin-2-one

Ketene
463-51-4

Ketene

benzylidene phenylamine
538-51-2

benzylidene phenylamine

phenyl isocyanate
103-71-9

phenyl isocyanate

Conditions
Conditions Yield
at 680 ℃; under 0.002 Torr; Yields of byproduct given;
5%
at 680 ℃; under 0.002 Torr; Yield given. Title compound not separated from byproducts;
5%
{Co2(μ-CH2)(μ-CHCH3)(CO)4(μ-dppm)}

{Co2(μ-CH2)(μ-CHCH3)(CO)4(μ-dppm)}

Ketene
463-51-4

Ketene

Co2(CO)4(μ-CO)2(μ-bis(diphenylphosphino)methane)
52615-19-7

Co2(CO)4(μ-CO)2(μ-bis(diphenylphosphino)methane)

prop-1-en-1-one
6004-44-0

prop-1-en-1-one

Conditions
Conditions Yield
With carbon monoxide; In neat (no solvent); pyrolysis under CO atmosphere at 25°C;; not isolated; detected by NMR spectroscopy; ketenes trapped by reaction with CD3OD with formation of the corresponding esters;;
70%
85%
80%
{Co2(μ-CH2)(μ-CHCH3)(CO)4(μ-dppm)}

{Co2(μ-CH2)(μ-CHCH3)(CO)4(μ-dppm)}

Ketene
463-51-4

Ketene

{Co2(μ-SO2)2(CO)4(μ-dppm)}

{Co2(μ-SO2)2(CO)4(μ-dppm)}

prop-1-en-1-one
6004-44-0

prop-1-en-1-one

Conditions
Conditions Yield
With sulfur dioxide; In neat (no solvent); reaction for a longer period of time;; not isolated; detected by NMR spectroscopy; ketenes trapped by reaction with CD3OD with formation of the corresponding esters;;
15%
25%
25%
butanone
78-93-3

butanone

Ketene
463-51-4

Ketene

prop-1-en-1-one
6004-44-0

prop-1-en-1-one

Conditions
Conditions Yield
thermische Zersetzung;
at 600 ℃;
{Co2(μ-CH2)(μ-CHCH3)(CO)4(μ-dppm)}

{Co2(μ-CH2)(μ-CHCH3)(CO)4(μ-dppm)}

hexafluoro-2-butyne
692-50-2

hexafluoro-2-butyne

Ketene
463-51-4

Ketene

{Co2(μ-CF3CCCF3)(CO)4(μ-dppm)}
84896-13-9,108151-17-3

{Co2(μ-CF3CCCF3)(CO)4(μ-dppm)}

prop-1-en-1-one
6004-44-0

prop-1-en-1-one

Conditions
Conditions Yield
In neat (no solvent); not isolated; detected by NMR spectroscopy; ketenes trapped by reaction with CD3OD with formation of the corresponding esters;;
25%
35%
50%

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