Reactions of free radicals with aromatic compounds in the gaseous phase. II. Kinetics of the reaction of methyl radicals with phenol

1965 ◽  
Vol 18 (1) ◽  
pp. 20 ◽  
Author(s):  
MFR Mulcahy ◽  
DJ Williams

Knowledge of the reactivity of phenols towards simple free radicals is needed to throw light on the behaviour of the phenolic substances involved in the pyrolysis of coal and other organic materials. In the present investigation the reaction between methyl radicals and phenol vapour has been studied a t total pressures from 0.5 to 3 cmHg and temperatures from 445 to 547°K, the concentrations of methyl radicals and phenol being varied from 2 × 10-12 to 4 × 10-11 and 1 × 10-8 to 8 × 10-7 mole cm-3 respectively. The main products identified by gas chromatography were methane and o- and p-cresol, together with a little anisole and 2,4- and 2,6-dimethylphenol. The cresols are produced via hydrogen abstraction Diagram followed by combination of a methyl radical at a ring position of the phenoxy radical either ortho or para to the oxygen atom, e.g. in the case of the para position: Diagram The kinetics can be explained by postulating (a) that the keto forms of the cresols (methylcyclohexadienones) formed initially by reaction (6) have a finite lifetime in the gaseous phase and (b) that these molecules, which contain a tertiary hydrogen atom α to a system of a carbonyl bond and two carbon-carbon double bonds, partly undergo hydrogen abstraction by methyl radicals before they are able to enolize: CH3· + (HCH3 = C6H4 = O → CH4 + CH3C6H4O· The mechanism is consistent with the kinetics of formation of methane, the distribu- tion of the free electron in the phenoxy radical, the formation of o- and p-cresols as major products, the kinetics of formation of the cresols, and the high reactivity of the intermediate product towards methyl radicals.

1967 ◽  
Vol 20 (6) ◽  
pp. 1155 ◽  
Author(s):  
MFR Mulcahy ◽  
BG Tucker ◽  
DJ Williams ◽  
JR Wilmshurst

The kinetics of the reaction between methyl radicals and anisole have been studied at temperatures between 453 and 539�K and total pressures between 10 and 30 torr. The concentrations of methyl radicals ranged from 2 x 10-12 to 5 x 10-11 mole and those of anisole from 10-7 to mole cm-3. The reaction proceeds mainly by the mechanism ������������������ C6H5OCH3+CH3· → C6H5OCH2·+CH4���������������� (1)����������������� C6H5OCH2·+CH3· → C6H5OC2H5�������������������� (2)���������������� ���������C6H5OCH2· → C6H5CHO+H·������������������ (3) At 487�K attack on the aromatic ring to yield methyl anisoles is about twelve times slower than reaction (1). The Arrhenius parameters for reactions (1) and (8) are: log10(A1 cm3 mole-1 sec-1) = 11.7 � 0.3, and E1 = 10.5 � 0.8 kcal mole-1; log10(A8 sec-1) = 12.5, and E8 = 21 kcal mole-1. The last two values are based on the assumption that the kinetics of reaction (2) are similar to those of the recombination of methyl radicals. The rate of reaction (1) is about half that of the corre- sponding reaction with toluene and about five times that of the reaction with ethane in the above temperature range.


1964 ◽  
Vol 17 (12) ◽  
pp. 1329 ◽  
Author(s):  
MFR Mulcahy ◽  
DJ Williams ◽  
JR Wilmshurst

The kinetics of abstraction of hydrogen atoms from the methyl group of the toluene molecule by methyl radicals at 430-540�K have been determined. The methyl radicals were produced by pyrolysis of di-t-butyl peroxide in a stirred-flow system. The kinetics ,agree substantially with those obtained by previous authors using photolytic methods for generating the methyl radicals. At toluene and methyl-radical concentrations of about 5 x 10-7 and 10-11 mole cm-3 respectively the benzyl radicals resulting from the abstraction disappear almost entirely by combination with methyl radicals at the methylenic position. In this respect the benzyl radical behaves differently from the iso-electronic phenoxy radical, which previous work has shown to combine with a methyl radical mainly at ring positions. The investigation illustrates the application of stirred-flow technique to the study of the kinetics of free-radical reactions.


Author(s):  
Nguyen Huu Tho ◽  
Nguyen Vo Hieu Liem ◽  
Nguyen Thi Huynh Nhu ◽  
Nguyen Thi Hong ◽  
Ngo Vo Thanh ◽  
...  

The reaction paths of the reaction of methyl radical with propanol-2 (i-C3H7OH) were investigated in detail using density functional theory at B3LYP/6-311++G(3df,2p) level. There were seven reaction pathways which form seven products including CH4 + (CH3)2COH, CH4 + (CH3)2CHO, CH4 + CH3CHOHCH2, CH3OH + CH3CHCH3, C2H6 + CH3CHOH, (CH3)2CH-O-CH3 + H and (CH3)3CH + OH. The results of analysis of the reaction paths and thermokinetic parameters showed that methane could be generated from three different channels. The removed H-atom from secondary carbon atom in the propanol-2 molecule is the most favorable of this reaction system. Keywords Methyl, propanol-2, B3LYP, transition state References [1] I. R. Slagle, D. Sarzyński, and D. Gutman, “Kinetics of the reaction between methyl radicals and oxygen atoms between 294 and 900 K,” Journal of Physical Chemistry, 1987.[2] L. Rutz, H. Bockhorn, and J. W. Bozzelli, “Methyl radical and shift reactions with aliphatic and aromatic hydrocarbons: Thermochemical properties, reaction paths and kinetic parameters,” in ACS Division of Fuel Chemistry, Preprints, 2004.[3] N. H. Tho and N. X. Sang, “Theoretical study of the addition and hydrogen abstraction reactions of methyl radical with formaldehyde and hydroxymethylene,” J. Serb. Chem. Soc.; OnLine First - OLF, 2018.[4] D. Ferro-Costas et al., “The Influence of Multiple Conformations and Paths on Rate Constants and Product Branching Ratios. Thermal Decomposition of 1-Propanol Radicals,” Journal of Physical Chemistry A, p. 4790−4800, 2018.[5] M. T. Holtzapple et al., “Biomass Conversion to Mixed Alcohol Fuels Using the MixAlco Process,” Applied Biochemistry and Biotechnology, 1999.[6] C. R. Shen and J. C. Liao, “Metabolic engineering of Escherichia coli for 1-butanol and 1-propanol production via the keto-acid pathways,” Metabolic Engineering, 2008.[7] A. Frassoldati et al., “An experimental and kinetic modeling study of n-propanol and iso-propanol combustion,” Combustion and Flame, vol. 157, pp. 2–16, 2010.[8] M. Z. Jacobson, “Effects of ethanol (E85) versus gasoline vehicles on cancer and mortality in the United States,” Environmental Science and Technology, 2007.[9] P. Gray and A. A. Herod, “Methyl radical reactions with ethanol and deuterated ethanols,” Transactions of the Faraday Society, 1968.[10] Z. F. Xu, J. Park, and M. C. Lin, “Thermal decomposition of ethanol. III. A computational study of the kinetics and mechanism for the CH3+C2H5OH reaction,” Journal of Chemical Physics, 2004.[11] N. H. Tho and D. T. Quang, “Nghiên cứu lý thuyết đường phản ứng của gốc metyl với etanol,” Vietnam Journal of Chemistry, vol. 56, no. 3, pp. 373–378, Jun. 2018.[12] N. H. Tho and N. X. Sang, “Kinetics of the Reaction of Methyl Radical with Methanol,” VNU Journal of Science: Natural Sciences and Technology; Vol 34 No 1DO - 10.25073/2588-1140/vnunst.4725 , Mar. 2018.[13] T. W. Shannon and A. G. Harrison, “The reaction of methyl radicals with methyl alcohol,” Canadian Journal of Chemistry, vol. 41, pp. 2455–2461, 1963.[14] S. L. Peukert and J. V. Michael, “High-temperature shock tube and modeling studies on the reactions of methanol with d-atoms and CH3-radicals,” Journal of Physical Chemistry A, 2013.[15] P. Gray and A. A. Herod, “Methyl radical reactions with isopropanol and methanol, their ethers and their deuterated derivatives,” Transactions of the Faraday Society, 1968.[16] A. D. Becke, “Density functional thermochemistry. I. The effect of the exchange only gradient correction,” Journal of Chemical Physics, vol. 96, p. 2155, 1992.[17] A. D. Becke, “Density-functional thermochemistry. II. The effect of the Perdew-Wang generalized-gradient correlation correction,” The Journal of Chemical Physics, vol. 97, p. 9173, 1992.[18] A. D. Becke, “Density-functional thermochemistry. III. The role of exact exchange,” The Journal of Chemical Physics, vol. 98, p. 5648, 1993.[19] W. Yang, R. G. Parr, and C. Lee, “Various functionals for the kinetic energy density of an atom or molecule,” Physical Review A, vol. 34 (6), pp. 4586–4590, 1986.[20] W. J. Hehre, L. Radom, P. V. R. Schleyer, and J. A. Pople, Ab Initio Molecular Orbital Theory. 1986.[21] M. P. Andersson and P. Uvdal, “New scale factors for harmonic vibrational frequencies using the B3LYP density functional method with the triple-zeta basis set 6-311+G(d,p).,” The journal of physical chemistry. A, vol. 109, pp. 2937–2941, 2005.[22] Frisch, M. J.; Trucks, G. W.; Schlegel, H.B.; Scuseria, G.E.; Robb, M.A.; Cheeseman, J. R., M. Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, J. L. Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, T. Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, and Y. . et al. Honda, “Gaussian 09 Revision C.01, Gaussian Inc. Wallingford CT.,” Gaussian 09 Revision C.01. 2010.[23] G. Herzberg, Electronic Spectra and Electronic Structure of Polyatomic Molecules. 1966.[24] L. M. Sverdlov, M. A. Kovner, and E. P. Krainov, Vibrational spectra of polyatomic molecules. New York; Chichester; Jerusalem; London: Wiley ; Israel Program for Scientific Translations, 1974.[25] E. Hirota, “Anharmonic potential function and equilibrium structure of methane,” Journal of Molecular Spectroscopy, vol. 77, pp. 213–221, 1979.[26] P. Venkateswarlu and W. Gordy, “Methyl alcohol. II. Molecular structure,” The Journal of Chemical Physics, 1955.[27] E. . B. Goos A.; Ruscic, B., “Extended Third Millennium Ideal Gas and Condensed Phase Thermochemical Database for Combustion with Updates from Active Thermochemical Tables,” http://garfield.chem.elte.hu/Burcat/burcat.html August-2018.


2018 ◽  
Vol 83 (10) ◽  
pp. 1113-1122
Author(s):  
Huu Nguyen ◽  
Xuan Nguyen

The mechanism, thermochemistry and kinetics of the addition and hydrogen-atom abstraction reactions of the methyl radical with formaldehyde and hydroxymethylene were investigated by ab initio calculations. The potential energy surface (PES) of the reactions were calculated by single point calculations at the CCSD(T)/6-311++G(3df,2p) level based on geometries at the B3LYP/6-311++G(3df,2p) level. The rate constants of various product channels were estimated by the variational transition state theory (VTST) and are discussed for the seven reactions in the temperature range of 300?2000 K and at 101325 Pa pressure. The calculated results showed that all the hydrogen abstraction reactions are more favorable than the addition ones.


1976 ◽  
Vol 29 (7) ◽  
pp. 1483 ◽  
Author(s):  
NL Arthur ◽  
M Lee

Hydrogen abstraction from (CH3),S and CH3COCH3 by CH3 radicals CH3+CH3SCH3 → CH4+CH3SCH2 CH3 + CH3COCH3 → CH4 + CH3COCH2 has been studied in the temperature range 120-245�. The rate constants, based on the value of 1013.34cm3 mol-l s-1 for the recombination of CH3 radicals, are given by (k in cm3 mol-1 s-1, E in kJ mol-1, R = 0.008314 kJ K-1 mol-1): logk1 = (11.62 � 0.08) ? (38.35 � 0.68)/2.303RT logk3 = (11.61 � 0.05) ? (40.48 � 0.46)/2.303RT Combination of the results for (1) with thermochemical data gives a calculated value of Logk-1 = (11.8 -63.7/2.303RT for the rate constant of the reverse reaction. The results for CH3+(CH3)2S are compared with all of the available data for hydrogen abstraction by free radicals from both sulphur-containing compounds, and molecules of the type (CH3)xM.


Author(s):  
Nguyen Huu Tho ◽  
Nguyen Xuan Sang

This work studied theoretically in details the mechanism, kinetics and thermochemistry of reactions of methyl radical with methanol. The theoretical study was carried out by ab initio molecular orbital theory based on CCSD(T)/B3LYP/6-311++G(3df,2p) methods in conjunction variational transition state theory (VTST). Calculated results showed that, in the temperature range from 300K to 2000K, and the pressure at 760 Torr, temperature dependent rate constants of the reactions were: CH3 + CH3OH ® CH4 + CH2OH    k(T) = 2.146´10-27.T4.64.exp(-33.47[kJ/mol/RT), CH3 + CH3OH ® CH4 + CH3O       k(T) = 2.583´10-27.T4.52.exp(-29.56[kJ/mol/RT), CH3 + CH3OH ® H + CH3OCH3    k(T) = 1.025´10-23.T3.16.exp(-186.84[kJ/mol/RT) When the reaction temperature is above 730 K, the abstraction process of H in –CH3 group of methanol will occur faster. The abstraction process of H in –OH group dominates when the reaction temperature is below 730 K. Keywords Kinetic, methyl, methanol, ab initio References 1. Slagle, I.R., D. Sarzynski, and D. Gutman, Kinetics of the reaction between methyl radicals and oxygen atoms between 294 and 900 K. The Journal of Physical Chemistry, 1987. 91(16): p. 4375-4379.2. Rutz L., B.H., Bozzelli J. W., Methyl Radical and Shift Reactions with Aliphatic and Aromatic Hydrocarbons: Thermochemical Properties, Reaction Paths and Kinetic Parameters. American Chemical Society, Division Fuel Chemistry, 2004. 49(1): p. 451-452.3. Johnson, D.G., M.A. Blitz, and P.W. Seakins, The reaction of methylidene (CH) with methanol isotopomers. Physical Chemistry Chemical Physics, 2000. 2(11): p. 2549-2553.4. Cribb, P.H., J.E. Dove, and S. Yamazaki, A kinetic study of the pyrolysis of methanol using shock tube and computer simulation techniques. Combustion and Flame, 1992. 88(2): p. 169-185.5. Dombrowsky, C., et al., An Investigation of the Methanol Decomposition Behind Incident Shock Waves. Berichte der Bunsengesellschaft für physikalische Chemie, 1991. 95(12): p. 1685-1687.6. Krasnoperov, L.N. and J.V. Michael, High-Temperature Shock Tube Studies Using Multipass Absorption:  Rate Constant Results for OH + CH3, OH + CH2, and the Dissociation of CH3OH. The Journal of Physical Chemistry A, 2004. 108(40): p. 8317-8323.7. Shannon, T.W. and A.G. Harrison, The reaction of methyl radicals with methyl alcohol. Canadian Journal of Chemistry, 1963. 41(10): p. 2455-2461.8. Jodkowski, J.T., et al., Theoretical Study of the Kinetics of the Hydrogen Abstraction from Methanol. 3. Reaction of Methanol with Hydrogen Atom, Methyl, and Hydroxyl Radicals. The Journal of Physical Chemistry A, 1999. 103(19): p. 3750-3765.9. Alecu, I.M. and D.G. Truhlar, Computational Study of the Reactions of Methanol with the Hydroperoxyl and Methyl Radicals. 2. Accurate Thermal Rate Constants. The Journal of Physical Chemistry A, 2011. 115(51): p. 14599-14611.10. Peukert, S.L. and J.V. Michael, High-Temperature Shock Tube and Modeling Studies on the Reactions of Methanol with D-Atoms and CH3-Radicals. The Journal of Physical Chemistry A, 2013. 117(40): p. 10186-10195.11. Anastasi, C. and D.U. Hancock, Reaction of CH3 radicals with methanol in the range 525 <T/K < 603. Journal of the Chemical Society, Faraday Transactions, 1990. 86(14): p. 2553-2555.12. Dombrowsky, C. and H.G. Wagner, An investigation of the reaction between CH3 radicals and methanol at high temperatures. Berichte der Bunsengesellschaft für physikalische Chemie, 1989. 93(5): p. 633-637.13. Tsang, W., Chemical Kinetic Data Base for Combustion Chemistry. Part 2. Methanol. Journal of Physical and Chemical Reference Data, 1987. 16(3): p. 471-508.14. Becke, A.D., Density‐functional thermochemistry. II. The effect of the Perdew–Wang generalized‐gradient correlation correction. The Journal of Chemical Physics, 1992. 97(12): p. 9173-9177.15. Becke, A.D., Density‐functional thermochemistry. I. The effect of the exchange‐only gradient correction. The Journal of Chemical Physics, 1992. 96(3): p. 2155-2160.16. Becke, A.D., Density‐functional thermochemistry. III. The role of exact exchange. The Journal of Chemical Physics, 1993. 98(7): p. 5648-5652.17. Yang, W., R.G. Parr, and C. Lee, Various functionals for the kinetic energy density of an atom or molecule. Physical Review A, 1986. 34(6): p. 4586-4590.18. Hehre W. , R.L., Schleyer P. V. R. , and Pople J. A. and 30, Ab Initio Molecular Orbital Theory. 1986, New York: Wiley.19. Andersson, M.P. and P. Uvdal, New Scale Factors for Harmonic Vibrational Frequencies Using the B3LYP Density Functional Method with the Triple-ζ Basis Set 6-311+G(d,p). The Journal of Physical Chemistry A, 2005. 109(12): p. 2937-2941.20. Raghavachari, K., et al., A fifth-order perturbation comparison of electron correlation theories. Chemical Physics Letters, 1989. 157(6): p. 479-483.21. M.J. Frisch, G.W.T., H.B. Schlegel, et al., GAUSSIAN 09, Revision C.01, Gaussian Inc., Wallingford CT, 2010.22. Robson Wright, M., Theories of Chemical Reactions, in An Introduction to Chemical Kinetics. 2005, John Wiley & Sons, Ltd. p. 99-164.23. Goos, E.B., A.; Ruscic, B., Extended Third Millennium Ideal Gas and Condensed Phase Thermochemical Database for Combustion with Updates from Active Thermochemical Tables. http://garfield.chem.elte.hu/Burcat/burcat.html, October, 2017.


1982 ◽  
Vol 60 (12) ◽  
pp. 1486-1492 ◽  
Author(s):  
Ionel Rosenthal ◽  
Magdi M. Mossoba ◽  
Peter Riesz

The photochemical reactions of several carbonyl-containing compounds investigated by spin-trapping with 2-methyl-2-nitrosopropane revealed different modes of scission depending on the structure of the initial compound. Thus, in photo-Fries rearrangements, the acyl radical was detected. 1,3-Diphenyl-2-propanone decarbonylated to yield the benzyl radical. Finally, valerophenone yielded the radicals expected by γ-hydrogen abstraction. In a dark reaction, dimethyl sulfoxide reacts with NaOH to generate methyl radicals. The latter result suggests the need for caution in the use of dimethyl sulfoxide with 2-methyl-2-nitrosopropane for the detection of hydroxyl radicals.


1974 ◽  
Vol 52 (11) ◽  
pp. 2171-2174 ◽  
Author(s):  
Frederick Peter Sargent ◽  
Marshall Grant Bailey ◽  
Edward Michael Gardy

A comparison of both the e.s.r. spectra and the thermal stability of the radicals produced in γ radiolysis and 185 nm photolysis of acetonitrile shows that the former are not free methyl radicals. The initial species formed by γ radiolysis can be converted by photobleaching into a methyl radical weakly associated with a cyanide ion. The methyl radical of this CH3---CN−pair decays via hydrogen abstraction, whereas the free methyl radicals produced by 185 nm photolysis of acetonitrile are quite stable at 77 K. We ascribe the low energy of activation for the hydrogen abstraction reaction in the γ irradiated samples not primarily to quantum mechanical tunnelling but to perturbation by the cyanide ion.


1958 ◽  
Vol 36 (1) ◽  
pp. 258-267 ◽  
Author(s):  
C. A. McDowell ◽  
L. K. Sharples

The photochemical oxidation of propionaldehyde has been studied in the gaseous phase at 23 °C. and a wavelength of 3130 Å. With pressures of oxygen varying from 0.3 mm. to 100 mm. Hg it has been established that the reaction obeys the same kinetic law as that found for the corresponding reaction with acetaldehyde, namely:[Formula: see text]where k3 is the velocity constant for the propagating reaction [3]:[Formula: see text]and k6 is the velocity constant for the terminating reaction [6]:[Formula: see text][Formula: see text]is the rate of initiation and it is regarded as being a composite quantity representing the rate of formation of propionyl radicals, which are thought to be the initiators of the oxidation chain. The propionyl radicals are thought to be formed by two processes: (a) from the subsequent reactions of free radicals produced in the primary free radical process which occurs when propionaldehyde absorbs a quantum of radiation at 3130 Å, and (b) from the subsequent reactions, with oxygen, of excited states of propionaldehyde, which are also thought to be formed by the absorption of light of wavelength 3130 Å.


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