N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate as a highly active and selective esterification catalyst

N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate (1) was found to be a very active esterification catalyst that promotes condensation of equal mole amount of carboxylic acids and alcohols under mild conditions. This catalyst is also highly selective towards carboxylic acid and alcohol substrates at ambient temperature.