Manufacture of malic acid

Abstract

Synthesis of malic acid from maleic and/or fumaric acid in a reaction zone whose surfaces exposed to the reaction mixture consist of titanium, zirconium or tantalum and alloys containing at least 90% of one of these metals.

I claim: 
     
       1. In a process for the synthesis of malic acid from an acid selected from the group consisting of maleic acid, fumaric acid and mixtures thereof in an aqueous reaction mixture at elevated temperature and pressure, the improvement of performing the synthesis in a zone whose surfaces exposed to the reaction mixture consist of at least one material from the group of titanium, zirconium, and tantalum and alloys containing at least 90% of said metal. 
     
     
       2. A process according to claim 1 wherein said material is titanium. 
     
     
       3. A process according to claim 1 wherein said material is zirconium. 
     
     
       4. A process according to claim 1 wherein said material is tantalum. 
     
     
       5. A process according to claim 1 wherein said acid is maleic acid. 
     
     
       6. A process according to claim 1 wherein said acid is fumaric acid. 
     
     
       7. A process according to claim 1 wherein said acid is a mixture of maleic and fumaric acids. 
     
     
       8. A process for the synthesis of malic acid from maleic/fumaric acid reaction mixture which comprises heating an equeous maleic/fumaric acid solution at between 160° and 250° C. at a pressure of at least 150 p.s.i.g. for at least two hours, said synthesis being conducted in a zone whose surfaces exposed to the reaction mixture consist of at least one material from the group of titanium, zirconium and tantalum and alloys containing at least 90% of said metal. 
     
     
       9. A process according to claim 5 wherein said synthesis is performed at temperatures between 180° and 220° C., at a pressure between 200 and 260 p.s.i.g. for between 3 and 5 hours.