A KINETIC-STUDY OF THE THERMAL DECARBOXYLATION OF ALPHA,ALPHA-DIFLUORO BETA-LACTONES

The rates of thermolysis of alpha,alpha-difluoro beta-lactones 1, lead ing to CO2 and 1,1-difluoro olefins, have been obtained in the gas pha se and in solution, and the activation parameters are reported. Ab ini tio calculations on the fluoro and nonfluorinated beta-lactone systems are also reported. The gas-phase kinetic and theoretical results are discussed in terms of a probable concerted, asynchronous, nonpolar mec hanism, whereas the solution kinetics, which include extensive solvent effect studies, are discussed in terms of apolar mechanism which prob ably involves formation of a zwitterionic intermediate.