Isocyanide dichloride

Isocyanide dichlorides are organic compounds containing the RN=CCl2 functional group. Classically they are obtained by chlorination of isocyanides. Phenylcarbylamine chloride is a well-characterized example.

Preparation and reactions
Chlorination of organic isothiocyanates is also well established:
 * RN=C=S +  2Cl2  →  RN=CCl2  +  SCl2

Alkylisocyanates are chlorinated by phosphorus pentachloride:
 * RN=C=O +  PCl5  →  RN=CCl2  +  POCl3

Cyanogen chloride also chlorinates to give the isocyanide dichloride:
 * ClCN +  Cl2  →  ClN=CCl2

Reactions
Isocyanide dichlorides participate in Friedel-Crafts-like reactions, leading, after hydrolysis, to benzamides:
 * RN=CCl2 +  ArH  →  RN=C(Cl)Ar +  HCl
 * RN=C(Cl)Ar + H2O  →  R(H)NC(O)Ar  + HCl