Catalytic Esterification of Acetic Acid with Methanol; Comparison of Photocatalytic and Acid Catalysed Esterification

Methyl acetate is produced through catalytic esterification of acetic acid with methanol. Catalytic acceleration is induced by sulfuric acid or ion exchange resins respectively. Acceptable product yield is obtained by reactive distillation. Separation and isolation of methyl acetate has to overcome two azeotropes (methyl acetate – water and methyl acetate methanol). Scope of this project has been the investigation of photocatalytic methyl acetate formation. The process has been compared with esterification with the catalyst sulfuric acid. In both processes methyl acetate was separated from the reaction mixture by extraction and distillation. Mixed triarylsulphonium hexafluorphosphate salts (photoacid generator, PAG) are used to cure UV coatings and inks. Since PAG has the ability to generate Brönsted acids under UV irradiation it can promote esterification of acetic acid with methanol. The yield of ester formation can be controlled by extractive separation of the product. Kinetics and yield of the esterification was quantified from balances of the reaction phase and the solvent phase. For reasons of comparability with state of the art catalyst sulfuric acid the latter process was carried out following the same procedure of preparation except UVactivation.