Process Conditions for Production of D-[beta]-Acetylthioisobutyric Acid from Methyl DL-[beta]-Acetylthioisobutyrate with the Cells of Pseudomonas putida MR-2068

The process conditions concerned with the production of D-β-acetylthioisobutyric acid were investigated. Methyl DL-β-acetylthioisobutyrate as an enzyme substrate was produced from methyl methacrylate in 96.6% yield by allowing 1.0 mol of methyl methacrylate to react with 1.6 mol of thioacetic acid at 80°C for 6 h. Through the study of hydrolytic reaction of methyl DL-β-acetylthioisobutyrate with the cells of Pseudomonas putida MR-2068, it was found that D-β-acetylthioisobutyric acid having more than 98% (e.e.) optical purity was obtained when the reaction was done below pH 7.5 and below 50°C. For example, 10% (w/v) methyl DL-β-acetylthioisobutyrate in the reaction mixture was asymmetrically hydrolyzed by 0.2% (w/v) cells at 45°C at pH 7.0 for 18 h to give DAT having 98.2% (e.e.) optical purity in 49.7% yield. To prevent the decompositon and racemization of D-β-acetylthioisobutyric acid in the purification process, the use of a thin-film distillation apparatus for a continuous distillation was proposed to be an effective purification method.