Haloformimidates and 1-Halothioformimidates

The compounds under discussion are derivatives of 1-haloformimidic acid (I) and 1-halothioformimidic acid (II), respectively. 

The free acids are not known although their formation from isocyanic or isothiocyanic acid and one mole of a hydrogen halide can be visualized. While the esters of isocyanic acid, the isocyanates III, add one mole of hydrogen halide to afford the corresponding carbamic acid chlorides (IV), methyl isothiocyanate (V) adds hydrogen bromide to form a mixture of two isomers, to which 1-bromothioformidic acid structures VI and VII have been assigned ( ). 

The hitherto-synthesized derivatives are substituted on the nitrogen, with the exception of the hydrogen bromide adducts VIII of thiocyanates which have recently been synthesized by Allenstein and Quis ( ). 

Another class of thioformimidic acid derivatives, the S-chlorides IX, is obtained by controlled addition of chlorine to isothiocyanates (io.29.30j or thiocyanogen chloride ( ). Ottmann and Hooks name 

S-chloroisothiocarbamoyl chlorides for compounds IX, while Chemical Abstracts relates their name to formimidoyl chloride, i.e., l-(chlorothio)-formimidoyl chloride. 

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Asymmetrical Stretching Vibration of the C=N Group in 1-Haloformimidates and 1-Halothioformimidates... 

The displacement of one chloro group in carbonimidoyl dichlorides by alkoxide, phenoxide, or thiolate ion is the best general method of synthesis of 1-haloformimidates or 1-halothioformimidates. However, several other methods of synthesis are available and since nucleophilic displacement of the halo group is easily accomplished, further utilization of these reactive intermediates in organic chemistry is anticipated. 

The hitherto reported 1-haloformimidates, 1-halothioformimidates, and l-(chlorothio)formimidoyl chlorides are listed in Tables I-III. 

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