From Thiocyanates and Isothiocyanates

Recently Allenstein and Quis ( ) investigated the addition of hydrogen halides to thiocyanates. While with hydrogen chloride only labile adducts have been observed, hydrogen bromide adds to methyl- and phenylthio-cyanate to afford 2 1 adducts, for which structure XX has been assigned on the basis of infrared spectroscopy ( ). 

The corresponding 1-chloroderivative may be an intermediate in the transformation of formimidoyl chloride to thiocyanates by means of sulfenyl chloride ( ) (see page 142). 

The above 1-bromothioformimidates XX are the only known derivatives of thioformimidic acid, which are not substituted on the nitrogen. 

The addition of hydrogen bromide to methyl isothiocyanate affords, depending upon reaction conditions, two isomers, XXI and XXII ( ). The latter is the predominant product and it is difficult to obtain pure XXL Actually, Allenstein and Quis ( ) could not repeat the formation of this compound. 

From iso thiocyanates and one equivalent of chlorine, relatively stable 1 1 adducts can be obtained While Dyson and Harrington ( ) 

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