Thermal and alkali-catalyzed hydrolysis study of R,R' ,4,4' -cyclohexylidenediphenyloxyacetic acids and their ethyl esters

R,R',4,4'-Cyclohexylidenediphenyloxyacetic acid (PAAC-1 to PAAC-7, R = H, CH 3 , Cl, Br, NO 2 and R' = H, Cl, Br, NO 2 ) are thermally stable up to 226-320°. Kinetic parameters are interpreted in light of the nature of the substituents. A large and positive magnitudes of ΔS* indicated less ordered transition state than individual phenoxy acid molecules. The endo- or exothermic DTA transitions supported some physical or chemical changes. Various thermodynamic parameters of ethyl esters of the above acids in MeOH-H 2 O (1: 1, v/v) have been determined condctometrically from second order rate constants at 30, 35 and 40° and are interpreted in terms of the nature of substituents on the reaction rate. The experimental data are in accordance with the bimolecular acyl fission mechanism. A large and negative ΔS* and small A indicate highly ordered transition state as compared to individual ester molecules and it is rate-determining step.