General base-catalyzed hydrolysis and carbonyl-¹⁸O exchange of N-(4-nitrobenzoyl)pyrrole

Abstract

Base-promoted hydrolysis kinetics for N-(4-nitrobenzoyl)pyrrole (1) have been measured as a function of buffer concentration at several pH values at 25°C. In addition carbonyl-18O exchange kinetics have been determined at a single pH value (9.48) as a function of 1,4-diazobicyclo[2.2.2]octane (DABCO) concentration. At zero buffer concentration the measured ratio of 18O exchange to hydrolysis (kex/khyd) is approximately 0.04, and this value increases and finally levels off at about 0.23 as the DABCO concentration is increased. These observations are consistent with the buffer acting as a general-base to catalyze both the attack of water to generate an anionic tetrahedral intermediate (To-) and the breakdown of To- to give hydrolysis products.Key words: amide, hydrolysis, catalysis, general-base, tetrahedral intermediate.

The Crystal Structure of 3-(4′-Methoxyphenyl)propanoyl pyrrole of Piper lolot C.DC from Vietnam

“…Especially the values in the amide group and the double bonds in the pyrrole ring are in line with the dimethoxy derivative and a number of benzoyl and toluoyl substituted pyrrole derivatives (BENNET, SOMAYAJI, BROWN & SANTARSIERO, 1991;BEACH, BATCHELOR, EINSTEIN & BENNET, 1998).…”