THE NATURE OF THE TRANSITION-STATE IN AMIDES PYROLYSIS - THE RATES OF PYROLYSIS OF N-BENZOYL AND N-ACETYLPROPANAMIDE, N-BENZOYL AND N-ACETYL-2-METHYLPROPANAMIDE, AND N-THIOACETYLPROPANAMIDE

The rates of gas-phase elimination reactions of N-benzoyl and N-acetyl-propanamide and N-benzoyl and N-acetyl-2-methylpropanamide are measured and discussed. They undergo unimolecular first-order elimination reactions. The reactivities of N-benzoylamides have been compared with each other and with those of N-acetylamides. The kinetic data together with the product analysis reveals that, the statistical factor of the availability of beta-hydrogen atoms for elimination as well as steric factor are obscured by polar factor in gas-phase elimination reactions of N-benzoylamides while the statistical factor rather than electronic effect operates in each of N-acetylamides. (C) 1995 John Wiley & Sons, Inc.