PH DEPENDENT HYDROLYSIS OF 2-HYDROXYPROPYL METHANETHIOSULFONATE

The hydrolysis of 2-hydroxypropyl methanethiolsulfonate (HPMTS), an in dustrial water treatment microbicide, was investigated at 25 degrees C and at three pH values (pH 5, 7, and 9). Radiolabeled (C-14) HPMTS at a concentration of 100 mg/L was used to determine rate constants and to identify hydrolytic degradation products. The hydrolysis at all thr ee pHs followed pseudo-first-order kinetics with rate constants of 5.8 x 10(-4), 7.6 x 10(-2), and 7.3 h(-1) at pH 5, 7, and 9, respectively . Two major radiolabeled hydrolytic degradation products were observed at all three pH values and were identified to be bis(2-hydroxyisoprop yl)disulfide and bis(2-hydroxypropyl)disulfide by particle beam LC/MS. On the basis of the observed degradation products, a hydrolytic degra dation pathway for HPMTS using propylene epoxide as a reactive interme diate was postulated.