Pyridinium methanesulfonate (m.p. 185°C) and pyridinium
p-toluenesulfonate (m.p. 121°C) were used as catalysts and media for the esterification of carboxylic acids with primary alcohols
to give the corresponding esters selectively in high yields. The high melting points of these pyridinium salts did not prevent
their application as ionic liquid medium for these reactions which were performed at 90°C.
Keywords Ionic liquids - pyridinium methanesulfonate - pyridinium p-toluenesulfonate - esterification