Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein-Ponndorf-Verley reactions

Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein-Ponndorf-Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein-Ponndorf-Verley reaction. [GRAPHICS] .

Automated summary

A catalytic system consisting of AlCl3/Et3N in CH2Cl2 has been developed to selectively convert a wide range of aliphatic and aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature with high yields. Higher AlCl3 content favors the Cannizzaro reaction, while lower content favors the Tishchenko reaction. The presence of hydride donor alcohols in the reaction mixture directs the reaction towards the Meerwein-Ponndorf-Verley reaction.