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Notes: Disagreements in rate constants and parameters between published results on the decomposition of 1,1-difluoroethane and 1,1,1-trifluoroethane are shown to originate from incorrect specification and setting of reaction conditions in one of the studies. When corrected, applicable results are in excellent agreement.

Notes: 1,1,2,2-Tetramethylcyclopropane (TTMC) has been decomposed in a single-pulse shock tube. The main reaction process is Side reactions are unimportant. From comparative rate experiments (with cyclohexene decomposition as standard) the rate expression for these reactions are \documentclass{article}\pagestyle{empty}\begin{document}$$ k_1 = 10^{14.82} \exp \left( {{{ - 31,320} \mathord{\left/ {\vphantom {{ - 31,320} {\rm T}}} \right. \kern-\nulldelimiterspace} {\rm T}}} \right)\sec ^{ - 1} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ k_2 \sim 10^{16.0} \exp \left( {{{ - 35,050} \mathord{\left/ {\vphantom {{ - 35,050} T}} \right. \kern-\nulldelimiterspace} T}} \right)\sec ^{ - 1} $$\end{document} These numbers are consistent with a «best» value for cyclohexene decomposition of \documentclass{article}\pagestyle{empty}\begin{document}$$ k\left( {c{\rm C}_{\rm 6} {\rm H}_{{\rm 10}} \to 1,3 - {\rm C}_{\rm 4} {\rm H}_{\rm 6} + {\rm C}_{\rm 2} {\rm H}_{\rm 4} } \right) = 10^{15.15} \exp \left( {{{33,500} \mathord{\left/ {\vphantom {{33,500} {\rm T}}} \right. \kern-\nulldelimiterspace} {\rm T}}} \right)\sec ^{ - 1} $$\end{document}

Notes: The experimental results on decomposition and combination reactions involving O3, HNO3, NH3, C2N2, and NO2Cl over extended temperature and pressure ranges are compared with the deductions from RRKM calculations. Quantitative fits of the data over the entire range are possible only if the external (overall) rotations are assumed to be involved in the reactions. Recommended rate constants for the reactions O + O2 + N2 → O3 + N2 and OH + NO2 + N2 → HNO3 + N2 are presented.

Notes: 2,4-Dimethylhexene-l has been decomposed in single-pulse shock tube experiments. Rate expressions for the initial reactions are \documentclass{article}\pagestyle{empty}\begin{document}$$ k(C_4 H_7 - S - C_4 H_9 \to C_4 H_7 .(isobutenyl) + s - C_4 H_9 .) = 10^{15.6} \exp (- 33,200/T)\sec ^{ - 1} $$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$$ k(C_4 H_7 - S - C_4 H_8 \to _i C_4 H_8 + n - C_4 H_8 .) = 10^{12.5} \exp (- 26,900/T)\sec ^{ - 1} $$\end{document} sec-1 at 1.5-5 atm and 1050°K. This leads to ΔH°f300 (CH2 = C(CH3)CH2) = 124 kJ/mol, or an allylic resonance energy of 50 kJ/mol. Rate expressions for the decomposition of the appropriate olefins which yield isobutenyl radicals and methyl, ethyl, isopropyl, n-propyl, t-butyl, and t-amyl radicals, respectively, are presented. The rate expression for the decomposition of isobutenyl radical is \documentclass{article}\pagestyle{empty}\begin{document}$$ k{\rm (C}_{\rm 4} H_7 .(isobutenyl) \to C_3 H_4 (allene) + CH_3 .) = 10^{13.3} \exp (- 2,500/T)\sec ^{ - 1} $$\end{document} (at the beginning of the fall-off region). For the combination of isobutenyl and methyl radicals, the rate constant at 1020°K is \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm k(C}_{\rm 4} H_7 .(isobutenyl) + CH_3 . \to 2 - methylbutene - 1) = 10^{10.3} 1./mol\sec $$\end{document} Combination of this number and the calculated rate expression for 2-methylbutene-1 decomposition gives SC4H7. (1100) = 470 J/mol °K. This yields \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm k(C}H_3 + C_3 H_4 (allene) \to C_4 H_7 .(isobutenyl) = 10^{8.2} \exp (- 2,500/T)l./mol\sec $$\end{document} It is demonstrated that an upper limit for the rate of hydrogen abstraction by isobutenyl from toluene is \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm k(C}_{\rm 4} H_7 . + \emptyset CH_3 \to iC_4 H_8 + \emptyset CH_2 .)\underline \le 10^{8.3} \exp (- 6,000/T)l./mol\sec $$\end{document}

Notes: 3,3-Dimethylbutanol-2 (3,3-DMB-ol-2) and 2,3-dimethylbutanol-2 (2,3-DMB-ol-2) have been decomposed in comparative-rate single-pulse shock-tube experiments. The mechanisms of the decompositions are The rate expressions are \documentclass{article}\pagestyle{empty}\begin{document}$$k_{\rm B} (2,3{\rm - DBM - ol - 2}) = 10^{16.24} {\rm exp}(- 37,400/T)\sec ^{- 1}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$k_{\rm EP} (2,3{\rm - DBM - ol - 2}) = 10^{14.17} {\rm exp}(- 32,300/T)\sec ^{- 1}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$k_{\rm ET} (2,3{\rm - DBM - ol - 2}) = 10^{13.66} {\rm exp}(- 32,700/T)\sec ^{- 1}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$k_{\rm B} (3,3{\rm - DBM - ol - 2}) = 10^{16.33} {\rm exp}(- 37,500/T)\sec ^{- 1}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$k_{\rm EP} (3,3{\rm - DBM - ol - 2}) = 10^{14.0} {\rm exp}(- 34,200/T)\sec ^{- 1}$$\end{document} They lead to D(iC3H7—H) - D((CH3)2(OH) C—H) = 8.3 kJ and D(C2H5—H) - D(CH3(OH) CH—H) = 24.2 kJ.These data, in conjunction with reasonable assumptions, give \documentclass{article}\pagestyle{empty}\begin{document}$$k(t{\rm C}_{\rm 4} {\rm H}_{\rm 9} {\rm OH} \to {\rm CH}_{\rm 3} \cdot + \cdot {\rm C(CH}_{\rm 3} {\rm)}_{\rm 2} {\rm OH}) = 10^{16.8} {\rm exp}(- 40,900/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$k(i{\rm C}_{\rm 3} {\rm H}_{\rm 7} {\rm OH} \to {\rm CH}_{\rm 3} \cdot + \cdot {\rm CH(CH}_{\rm 3} {\rm)OH}) = 10^{16.5} {\rm exp}(- 41,100/T)\sec ^{- 1}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$k(n{\rm C}_{\rm 3} {\rm H}_{\rm 7} {\rm OH} \to {\rm CH}_{\rm 3} \cdot + \cdot {\rm CH}_{\rm 2} {\rm CH}_{\rm 2} {\rm OH}) = 10^{16.2} {\rm exp}(- 41,100/T)\sec ^{- 1}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$k({\rm C}_{\rm 2} {\rm H}_{\rm 5} {\rm OH} \to {\rm CH}_{\rm 3} \cdot + \cdot {\rm CH}_{\rm 2} {\rm OH}) = 10^{16.4} {\rm exp}(- 42,500/T)\sec ^{- 1}$$\end{document}andThe rate expressions for the decomposition of 2,3-DMB-1 and 3,3-DMB-1 are \documentclass{article}\pagestyle{empty}\begin{document}$$ k(2,3{\rm - DMB - 1} \to {\rm CH}_3 \cdot + {\rm H}_2 {\rm C} = {\rm C}({\rm CH}_3 ) - \mathop {\mathop {\rm C}\limits^{\rm .} {\rm H}({\rm CH}_3 )) = 10^{16.0} \exp ( - 35,700/T)\sec ^{ - 1} } $$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$$ k(3,3{\rm - DMB - 1} \to {\rm CH}_{\rm 3} \cdot + {\rm H}_2 {\rm C = CH} - \mathop {\rm C}\limits^{\rm .} ({\rm CH}_3 )_2 ) = 10^{16.2} \exp ( - 35,500/T)\sec ^{ - 1} $$\end{document}

Notes: Cyclopentane has been decomposed in comparative-rate single-pulse shock-tube experiments. The pyrolytic mechanism involves isomerization to 1-pentene and also a minor pathway leading to cyclopropane and ethylene. This is followed by the decomposition of 1-pentene and cyclopropane. The rate expressions over the temperature range of 1000°-1200° K are \documentclass{article}\pagestyle{empty}\begin{document}$$ k(c-{\rm C}_{\rm 5} {\rm H}_{{\rm 10}} \to 1-{\rm C}_{\rm 5} {\rm H}_{{\rm 10}}) = 10^{16.1} \exp (- 42,700/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k(c-{\rm C}_{\rm 5} {\rm H}_{\rm 10} \to (c-{\rm C}_{\rm 3} {\rm H}_{\rm 6} + {\rm C}_{\rm 2} {\rm H}_{\rm 4}) = 10^{16.25} \exp (- 47,840/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k(1 - {\rm pentene} \to {\rm C}_{\rm 3} {\rm H}_{\rm 6} + {\rm C}_{\rm 2} {\rm H}_{\rm 5}) \sim 10^{16} \exp (- 35,900/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k(1 - {\rm pentene} \to {\rm C}_{\rm 3} {\rm H}_{\rm 6} + {\rm C}_{\rm 2} {\rm H}_{\rm 4}) \sim 10^{12.5} \exp (- 28,900/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k(c-{\rm C}_{\rm 3} {\rm H}_{\rm 6} \to {\rm C}_{\rm 3} {\rm H}_{\rm 6}) = 10^{14.3} \exp (- 31,100/T)\sec ^{- 1} {\rm at}\ {\rm 5}\ {\rm atm} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k(c-{\rm C}_{\rm 3} {\rm H}_{\rm 6} \to {\rm C}_{\rm 3} {\rm H}_{\rm 6}) = 10^{14.1} \exp (- 31,100/T)\sec ^{- 1} {\rm at}\ {\rm 1.7}\ {\rm atm} $$\end{document}Details of the cyclopentane decomposition processes are considered, and it appears that if the trimethylene radical is an intermediate, then ΔHf(trimethylene) ≤ 280 kJ/mol at 300°K.

Notes: The mechanism and initial rates of decomposition of cyclohexane and 1-hexene have been determined from single-pulse shock-tube experiments. The main initial processes involve isomerization of cyclohexane to 1-hexene, followed by decomposition of 1-hexene. From comparative rate experiments the following rate expressions have been derived: \documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm cyclohexane} \to 1 - {\rm hexene}) = 10^{16.7} \exp (- 44,400/T)\,\,\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k_B (1 - {\rm hexene} \to {\rm C}_{\rm 3} {\rm H}_{{\rm 5}} \cdot {\rm + nC}_{\rm 3} {\rm H}_{{\rm 7}} \cdot) = 10^{15.9} \exp (- 35,600/T)\,\,\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k_{\rm M} (1 - {\rm hexene} \to 2{\rm C}_{\rm 3} {\rm H}_6) = 10^{12.6} \exp (- 28,900/T)\,\,\sec ^{- 1} $$\end{document} The 1-hexene bond-braking reaction leads to an allylic resonance energy of 42.7 kJ and a heat of formation of allyl radicals of 176.6 kJ (300°K). There appear to be general relations relating the rate expressions for the decomposition of alkynes, alkanes, and alkenes. Studies on the induced decomposition of cyclohexane have also been carried out.

Notes: Several hydrocarbons have been pyrolyzed in a single pulse shock tube. Rate parameters for the main bond breaking step have been found to be \documentclass{article}\pagestyle{empty}\begin{document}$$ k\left\{{{\rm iC}_3 {\rm H}_7 {-\!-} {\rm CH}\left({{\rm CH}_3} \right){\rm CH} {\raise1pt\hbox{$\Relbar \kern-4pt{\Relbar}$}} {\rm CH}_2 \longrightarrow {\rm iC}_3 {\rm H}_7 \cdot + \cdot {\rm CH}\left({{\rm CH}_3} \right){\rm CH} {\raise1pt\hbox{$\Relbar \kern-4pt{\Relbar}$}} {\rm CH}_2} \right\} = 10^{15.70} \exp \left({{{- 32,500} \mathord{\left/ {\vphantom {{- 32,500} T}} \right. \kern-\nulldelimiterspace} T}} \right)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k\left\{{{\rm iC}_3 {\rm H}_7 {-\!-} {\rm C}\left({{\rm CH}_3} \right)_2 {\rm C}_2 {\rm H}_5 \longrightarrow {\rm iC}_3 {\rm H}_7 \cdot + \cdot {\rm C}\left({{\rm CH}_3} \right)_2 {\rm C}_2 {\rm H}_5} \right\} = 10^{16.15} \exp \left({{{- 35,900} \mathord{\left/ {\vphantom {{- 35,900} T}} \right. \kern-\nulldelimiterspace} T}} \right)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k\left\{{{\rm C}_2 {\rm H}_5 {-\!-} {\rm C}\left({{\rm CH}_3} \right)_2 {\rm C}_2 {\rm H}_5 \longrightarrow {\rm C}_2 {\rm H}_5 \cdot + \cdot {\rm C}\left({{\rm CH}_3} \right)_2 {\rm C}_2 {\rm H}_5} \right\} = 10^{16.57} \exp \left({{{- 38,800} \mathord{\left/ {\vphantom {{- 38,800} T}} \right. \kern-\nulldelimiterspace} T}} \right)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k\left\{{{\rm iC}_3 {\rm H}_7 {-\!-} {\rm CH}_2 {\rm C}_6 {\rm H}_5 \longrightarrow {\rm iC}_3 {\rm H}_7 \cdot + \cdot {\rm CH}_2 {\rm C}_6 {\rm H}_5} \right\} = 10^{15.23} \exp \left({{{- 34,800} \mathord{\left/ {\vphantom {{- 34,800} T}} \right. \kern-\nulldelimiterspace} T}} \right)\sec ^{- 1} $$\end{document} In combination with similar studies carried out earlier and through application of the well-established experimental rule (kr2(AB)/kr(AA)kr(BB))1/2 ∼ 2 where A and B are radicals and the rate constants are for the combination of these radicals, rate parameters for the thermal decomposition of all the hydrocarbons formed from any pair of the following radicals: methyl, ethyl, isopropyl, t-butyl, t-amyl, allyl, methylallyl, and benzyl have been calculated. The available calculated and experimental values of the decomposition rate constants are in excellent agreement. It appears that, with the possible exception of reactions involving the ejection of methyl radicals, the frequency factors per bond are nearly constant, depending only upon the type of carbon-carbon bond that is being broken. These values are all lower than those expected from the radical recombination rates.Heats of formation of ethyl, t-amyl, benzyl, methylallyl, n-propyl, s-butyl, isobutyl, neopentyl, and 3-pentyl radicals have been derived.Rate parameters for the decomposition of some simple ketones and ethers have also been estimated.

Notes: The life times of chemically activated alcohols have been determined using the high-pressure unimolecular rate parameters for thermal decomposition of alcohols from shocktube studies and RRKM calculations. They are compared with literature numbers (from insertion of 0(1D) into hydrocarbons). It is suggested that in some cases singlet oxygen carries excess energy into the hydrocarbon. The consequences of such an assumption are explored and discrepancies with previously published conclusions discussed.

Notes: Tertiary-amyl amine has been decomposed in single-pulse shock-tube experiments. Rate expressions for several of the important primary steps are \documentclass{article}\pagestyle{empty}\begin{document}$$ k(t{\rm C}_5 {\rm H}_{11 - {\rm NH}_2} \to t{\rm C}_5 {\rm H}_{11}\!\!\cdot + {\rm NH}_2\cdot) = 10^{15.9} \exp (-39,700/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm C}_2 {\rm H}_5- {\rm C}({\rm CH}_3)_2{\rm NH}_2 \to {\rm C}_2 {\rm H}_5 \cdot + \cdot{\rm C}({\rm CH}_3)_2{\rm NH}_2) = 10^{16.5} \exp (- 38,500/T)\sec ^{- 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k(t{\rm C}_5 {\rm H}_{11} {\rm NH}_2 \to {\rm C}_5 {\rm H}_{10} + {\rm NH}_3) 〈10^{14.5} \exp (- 37,200/T)\sec ^{- 1} $$\end{document}This leads to D(CH3—H) - D(NH2—H) = -10.5 kJ and D[(CH3)3C—H] - D[(CH3)2NH2C—H] = + 6 kJ.The present and earlier comparative rate single-pulse shock-tube data when combined with high-pressure hydrazine decomposition results-(after correcting for fall off effects through RRKM calculations) gives \documentclass{article}\pagestyle{empty}\begin{document}$$ [k_r^2 (t{\rm C}_5 {\rm H}_{11} \cdot,{\rm NH}_2 \cdot)/k_r (t{\rm C}_5 {\rm H}_{11} \cdot,t{\rm C}_5 {\rm H}_{11} \cdot)k_r ({\rm NH}_2 \cdot,{\rm NH}_2 \cdot)]^{1/2} \sim 2\,{\rm at}\,1100^o {\rm K} $$\end{document} where kr(…) is the recombination rate involving the appropriate radicals. This suggests that in this context amino radical behavior is analogous to that of alkyl radicals. If this agreement is exact, then \documentclass{article}\pagestyle{empty}\begin{document}$$ k_\infty ({\rm N}_2 {\rm H}_4 \to 2{\rm NH}_2 \cdot) = 10^{16.25} \exp (- 32,300/T)\sec ^{- 1} $$\end{document} Rate expressions for the primary step in the decomposition of a variety of primary amines have been computed. In the case of benzyl amine where data exist the agreement is satisfactory. The following differences in bond energies have been estimated: \documentclass{article}\pagestyle{empty}\begin{document}$$ D(i{\rm C}_3 {\rm H}_7 {-\!-} {\rm H}) {-\!-} D[{\rm CH}_3 ({\rm NH}_2){\rm CH} {-\!-} {\rm H}] = 14.3\,{\rm kJ} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ D({\rm C}_2 {\rm H}_5 {-\!-} {\rm H}) - D({\rm NH}_2 {\rm CH}_2 {-\!-} {\rm H}) = 15.9\,{\rm kJ} $$\end{document}