Catalytic Systems Containing p-Toluenesulfonic Acid for the Coupling Reaction of Formaldehyde and Methyl Formate

Abstract

The coupling reaction of formaldehyde (FA) and methyl formate (MF) to form methyl glycolate (MG) and methyl methoxy acetate (MMAc), catalyzed by p-toluenesulfonic acid ( p-TsOH) as well as assisted by different kinds of solvents or Ni-containing compounds, had been investigated. The results showed that when the reaction was carried out at 140 °C, with a molar ratio of FA to MF of 0.65: 1, molar fraction of p-TsOH to total feedstock of 11.0%, and reaction time of 3 h, the yield of MG and MMAc was 31.1% and 17.1%, respectively. p-TsOH catalyzed the coupling reaction by means of the synergistic catalysis of protonic acidity and soft basicity. Adding extra solvents to the reaction system was unfavorable for the reaction. The composite catalytic system consisting of p-TsOH and NiX 2 (X=Cl, Br, I) exhibited a high catalytic performance for the coupling reaction, and NiX 2 acted as a promoter in the reaction, whose promotion for the catalysis increased in the following order: NiCl 2<NiBr 2<NiI 2. The present system is less corrosive when compared with the previous system, in which strong inorganic liquid acids were used as catalysts.