Rate of formation of toluene from ethylbenzene

The rate of formation of toluene from ethylbenzene was studied at atmospheric pressure in the temperature range of 600–725°C in conventional flow equipment. Residence times were 0.55–1.7 s, and initial partial pressures of ethylbenzene (H 2 O diluent) were 0.05–0.17 atm. The rate of appearance of toluene measures [1] the rate of the reaction C 6 H 5 C 2 H 5 → C 6 H 5 CH   3 ˙+ CH   3 ˙ , with log k = 15.70 – 74.49 ± 3.2/θ. From the activation energy, E 0 for the decomposition is estimated to be 72.2 ± 3.2 kcal/mol. The results are compatible with those of Esteban et al. [2], for which regression analysis gives log k 1 = 14.79 – 70.76/θ. A composite, log k = 15.10 – 72.0/θ, fits both sets of data and is experimentally indistinguishable from Robaugh and Steina's [3] recent estimate by the VLPP technique or other estimates in the literature [4–6]. In light of the high overall conversion of ethylbenzene studied (2–80%), the industrial‐type flow equipment, and the widely differing methods of characterization and analysis, the excellent agreement with the results of [2,3,5] is worthy of note. The data are compatible with current estimates of the heat of formation of benzyl radicals [6,7].