PhCH CH Research Articles

α-Substitution plus Carbonyl Olefination via β-Oxido Phosphorus Ylids (S. C. O. O. P. Y.-Reactions) Scope and Stereoselectivity

Consecutive treatment of HOCH2CH2P+Ph3 Br- with BuLi, BzH, BuLi, and H2O afforded trans-PhCH:CHCH2OH in 95% isomeric purity and PhCH(OH)CH:CH2. The stereospecificity of the S.C.O.O.P.Y.-reactions (Schlosser, M. and Christmann, F. K., 1969) is discussed. [on SciFinder (R)]

Kinetics of the catalytic vapor-phase ammoxidation of ethylbenzene over chromium oxide

The kinetics of the catalytic vapor-phase ammoxidation of ethylbenzene over a chromium oxide catalyst have been studied in a flow system at atmospheric pressure. Styrene and benzonitrile were the main products in the ammoxidation of ethylbenzene, but neither acetophenone nor benzyl cyanide was detectable. The rate of ammoxidation of ethylbenzene is expressed as: k[PhCH 2CH 3] 0·73[O 2] 0·39, while the rate of formation of styrene as: k[PhCH 2CH 3] 0·78[O 2] 0·25 and that of the formation of benzonitrile as: k[PhCH 2CH 3] 0·55[O 2] 0·90. All these rates are almost independent of the concentrations of ammonia. The apparent activation energy for the ammoxidation of ethylbenzene is ca. 23 kcal/mole. The rate of ammoxidation of styrene is expressed as: k[PhCHCH 2] −0.10[O 2] 0·50, and independnet of the concentrations of ammonia. These results suggest that styrene is formed by the reaction between the adsorbed ethylbenzene and the adsorbed oxygen in a dissociated form (i.e. oxidative dehydrogenation), and that the main pathway for the ammoxidation of ethylbenzene is a consecutive reaction: PhCH 2CH 3 → PhCHCH 2 → PhCN. The rate equations of the formation of styrene and benzonitrile and the effectof the addition of styrene were interpreted in terms of the Langmuir-Hinshelwood mechanism. The rate constants ( k°) for the reaction of substrates on the catalyst surface and the adsorption equilibrium constants of reactant gases ( K) were compared with those in the ammoxidation of toluene.