Carboxylation of Hydroxyarenes With Potassium Salts of Alkylcarbonic Acid

Abstract

In this article it was demonstrated that potassium ethyl carbonate can be successfully utilized within the phenol and its derivatives carboxylation. The optimal reaction conditions for m-cresol were determined: substrate to potassium ethyl carbonate ratio 2:1, temperature 180°C, pressure 10 atmospheres and reaction time 6 hours. Importantly, the carboxylation of m-cresol is selective and resulted in the obtaining of 4-methyl-2-hydroxybenzoic acid in 90% yield.To study the impact of the nature and location of substituents in the phenyl ring on the yield of the desired products, carboxylation reactions of various phenol derivatives were carried out with the use of potassium ethyl carbonate. As a result of the investigation, the optimal carboxylation reaction parameters for each of the phenol derivatives were determined.This study may have practical applications in the development of laboratory and manufacturing approaches for the synthesizing of valuable hydroxybenzoic acids and their derivatives. It was discovered that carboxylation of phenol derivatives by potassium ethyl carbonate occurs via electrophilic substitution of the aromatic ring. The most active in this reaction are p-cresol (84%), mcresol (90%), o-cresol (80%) and resorcinol (73%). It was observed that p-chlorophenol (18%), pbromophenol (48%) and p-fluorophenol (58%) showed less pronounced activity.