Malononitrile → Benzothiazole, 2,2'-methylenebis-

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Reaction Steps

To produce the above compound, in a two-neck 100 ml round bottom flask with a condenser and a stir bar, malononitrile (2.64 g, 40 mmol) was dissolved in absolute ethanol (40 ml). 2-amino thiophenol (log, 80 mmol) was slowly added to this solution under stirring. Under a nitrogen blanket, the reaction mixture was heated and refluxed for six hours. After cooling, the flask was refrigerated overnight. Pale green crystals of bis(2-benzothiazolyl) methane that formed were recovered, following vacuum filtration, washing with hexane and drying (yield: 82%). 2.82 g (10 mmol) of the bis(2-benzothiazolyl) methane was dissolved in chloroform (50 ml) in an erlenmeyer flask. Hydrobromic acid (10 mmol) in glacial acetic acid was added dropwise with gentle stirring. A canary yellow precipitate formed within minutes, causing thickening of the reaction mixture. Stirring was continued for one hour at room temperature. A fine yellow powder was recovered, following filtration and washing with ether. The yield was quantitative and the bis(2-benzothiazolyl) methane monohydrobromide product was sufficiently pure to be used in the next step.

Provenance & Evidence