Abstract: Gem-diacetates were synthesized from corresponding aromatic or aliphatic aldehydes and acetic anhydride catalysed by acetic acid-assisted copper o-toluenesulfonate as synergistic catalysts at room temperature under solvent-free conditions. The catalytic activity of acetic acid-assisted copper o-toluenesulfonate was much higher than that without acetic acid under the same conditions. Only a molar ratio of 0.3% of copper o-toluenesulfonate to aldehyde was needed to complete the reaction in short time. After reaction, the copper o-toluenesulfonate could be easily recovered by phase separation and could be reused five times without distinct decrease in its catalytic activity.

Key words: acetic acid, copper o-toluenesulfonate, synergistic catalysis, aromatic aldehyde, aliphatic aldehyde, acetic anhydride, gem-diacetate