[CH3:1][SH:2].[CH:3]([N:6]1[C:10](Cl)=[N:9][C:8]([OH:12])=[N:7]1)([CH3:5])[CH3:4].S([O-])(O)(=O)=O.[K+]>[OH-].[Na+]>[CH:3]([N:6]1[C:10]([S:2][CH3:1])=[N:9][C:8]([OH:12])=[N:7]1)([CH3:5])[CH3:4]An amount of 19.6 g of methylmercaptan is added at -5°C, with stirring, to 200 ml of 5N aqueous sodium hydroxide solution. An addition is then made of 33 g of 1-isopropyl-5-chloro-3-hydroxy-1,2,4-triazole, and the mixture heated for 2 hours at 100°C. After cooling to 20°C, the solution is acidified by the addition of potassium hydrogen sulphate, and extracted with ethyl acetate. The ethyl acetate extract is dried over anhydrous magnesium sulphate; it is then concentrated in a water-jet vacuum, and the residue crystallised from a little methanol at -70°C. The obtained product is 1-isopropyl-5-methylmercapto-3-hydroxy-1,2,4-triazole with a melting point of 90°-92°C.
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