Electrosynthesis and characterization of 2-ethoxy benzoic acid at platinum electrode by Potentiostatic method

Abstract

Substituting ethoxy group in the ortho or para position in benzoic acid is practically not possible in conventional methods as carboxylic acid group is a deactivating group favoring substitution in the meta position. Moreover, in an aromatic ring, the electrophilic substitution is more pronounced. In the present work, ethoxy group which is a nucleophile is substituted in the ortho position. The synthesis is carried out electrochemically on platinum electrode at different pH conditions. Ethanol is used as both reagent as well as solvent. pH variation is achieved by the use of supporting electrolytes like sulphuric acid, potassium chloride and potassium hydroxide. As a prerequisite, cyclic voltammetric analysis of benzoic acid with reaction mixture is done to find out the oxidation feasibilities. The impact of the pH medium, the effect of scan rate variation and multiple scan are also studied. It is predicted that the electrooxidation of benzoic acid on platinum electrode is diffusion controlled and there is no polymer formation on the electrode. Polarization studies have also been performed to find out the working potential. Electrochemically ethoxylated product has been isolated and characterized using IR, NMR and Mass spectra. It is found that ortho ethoxy benzoic acid is obtained with greater purity with little by products.