Purification of mercaptobenzothiazole

Abstract From the Canadian patent

Crude MBT is purified and substantially decolorized by treating same with an alkaline solution to form an MBT salt solution, measuring pH of the salt solution when adding the alkaline solution until an abrupt rise in pH is observed and stopping addition of the alkaline solution in response thereto treating the, salt solution with a solvent to extract solvent-soluble impurities, oxidizing the salt solution by introducing oxygen into an enclosed vessel containing the salt solution and vigorously agitating the solution until oxygen uptake essentially stops, diluting the salt solution with water, filtering the salt solution to remove precipitated impurities, and concentrating the solution.