Kinetics of the acid-catalysed ring-opening reaction of 2-phenyl-4,4-dimethyl-2-oxazolin-5-one with the ethyl ester of DL-alanine

Abstract The kinetic behaviour of the acetic acid catalysed reaction of 2-phenyl-4,4-dimethyl-2-oxazolin-5-one ( 1 ) with the ethyl ester of DL -alanine ( 2 ) in CCl 4 , to give the ethyl ester of N-(N′-benzoyl-α-amino-isobutyryl)- DL -alanine ( 3 ) is investigated. Within the range of concentrations employed, the reaction follows the rate equation ν = k o + k [monomer] [oxa] [ester], where k o is the specific rate constant of the uncatalysed reaction, and k ′ is that of the catalysed reaction. The influence of the variation of 1 , 2 and acetic acid on the specific rate constant is studied. It is shown that only if the acetic acid monomer is regarded as the catalyst can the system be adequately described quantitatively. The participation of other acid species as catalysts is discussed.