Thiamine tetrahydrofurfuryl disulfide hydrochloride

To a solution of 20 parts of thiamine hydrochloride in 30 parts of water is added an aqueous solution of sodium hydroxide (7.2 parts of NaOH in 30 parts of water), and the mixture is cooled with water. The mixture is allowed to stand for 30 minutes, 60 parts of chloroform is added, followed by a solution of 30 parts of crude sodium tetrahydrofurfurylthiosulfate in 30 parts of water, and the whole is stirred for 30 minutes. The chloroform layer is separated and the aqueous layer is extracted twice with 20 parts of chloroform. All the chloroform solutions are combined and shaken with 50 parts of 5% hydrochloric acid. The acid solution is decolorized and neutralized with alkali carbonate, whereupon thiamine tetrahydrofurfuryl disulfide separates out in the resinous state but soon solidifies [MP 129 (decomp.)]. The yield is 16 parts. Recrystallization from ethyl acetate gives colorless prisms melting at 132°C (decomp.). 

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