A comparative LFER study of the reactivity of pyridineacetic, pyridineacetic acids N-oxide and substituted phenylacetic acids with diazodiphenylmethane in various alcohols

Abstract

Rate constants have been determined for the reactions of diazodiphenylmethane (DDM) with 3- and 4-pyridineacetic acid, 3- and 4-pyridineacetic acid N-oxide and some meta- and para-substituted phenylacetic acids in twelve alcohols. The determined rate constants, together with literature data, were used for calculation of Hammett r values in a series of alcohols. Secondary s constants have been calculated for substituents in meta and para-position of phenylacetic acids not given in literature, and also s constants for 3N, 3N–O, 4N and 4N–O in pyridineacetic acids, in alcohols used. The transmission of electronic effects through the phenylacetic acid system and pyridineacetic system is compared with that in benzene and pyridine. The multiple correlation of log k values for reaction of above acids in 12 alcohols with group of suitable solvent parameters was very successful.

Keywords

• substituted pyridineacetic and phenylacetic acids
• protic solvents
• solvent parameters
• Hammett correlation