GAS-PHASE ELIMINATION KINETICS OF ALPHA-BROMO-O-TOLUIC ACID - PARTICIPATION OF THE COOH GROUP

The elimination kinetics of alpha-bromo-o-toluic acid have been studie d over the temperature range of 623.3 - 673.6 K and pressure range of 22 - 43 Torr. The reaction products are phthalide and HBr gas. The rat e coefficient for the homogeneous unimolecular elimination is expresse d by the following equation: log k(1) (s(-1)) = (11.69 +/- 0.13) -(182 .1 +/- 1.6)kJ mol(-1)(2.303RT)(-1). The formation of phthalide product suggests participation of the carbonyl oxygen of the COOH group. The present result provides additional evidence of an intimate ion pair me chanism in the gas phase pyrolysis of some type of haloacids in the ga s phase.