A Greener Method for the Preparation of Fumaric Acid and Malic Acid from Maleic Acid

Maleic acid was converted into fumaric acid and malic acid in water under pressurization by heating up in the absence of catalyst.The ratio of fumaric acid to malic acid in the mixture of products could be tuned by varying the concentrations of the maleic acid in water solution.The higher the concentration of maleic acid,the higher was the ratio of fumaric acid to malic acid.When the concentration of maleic acid was 90% or 5%,the total yields of fumaric acid and malic acid were above 99% or 98% at 180(C for 20h,and the ratios of fumaric acid to malic acid were 9.4∶1 and 1∶2.9 respectivly.After the isolation of products,the mother liquid could be reused.Hereby this is a greener method for the preparation of fumaric acid and malic acid.