| 2-mercaptobenzothiazole (MBT) is an important rubber vulcanization accelerator in rubber industry. It’s also the raw material used to make many other accelerators. The technologies for manufacturing MBT, especially, purification of MBT were reviewed. Based on the literatures and the calculation by group contribution method, the solubility parameters of a series of solvents and some substances in crude MBT were obtained. Xylene, UN, M-2, M-1 were preliminarily screened out according to solubility parameter theory and similar dissolve mutually principle. The solubilities of all components of MBT product in these solvents were determined, which provide a reference to decide filtering temperature and solvent ratio for MBT purification process. Based on investigating purification effect of the solvents for crude MBT, the best solvent is M-2. The suitable purification conditions for M-2 were decided as follows:30min at extraction temperature 150℃ by liquid-liquid extraction method, solvent ratio 2:1(two times), decreasing temperature from 150℃ to 20-35℃ by 1℃/min and filtering. As a result, the yield of MBT product is more than 80%, its melting point is up to 176.6℃.the MBT content in product is more than 97%. The purification effect with M-2 as extractant is better than that of toluene, the current commercial extractant for MBT purification. M-2 could replace toluene to become the new commercial extractant for MBT purification. |
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