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

Chlorination of organic isothiocyanates is also well established:

RN=C=S + 2 Cl₂ → 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

Isocyanide dichlorides participate in Friedel-Crafts-like reactions, leading, after hydrolysis, to benzamides:^{[citation needed]}

RN=CCl₂ + ArH → RN=C(Cl)Ar + HCl

RN=C(Cl)Ar + H₂O → R(H)NC(O)Ar + HCl

The N=C bond is relatively inert.^: 15

Hydrogen fluoride displaces the chlorides to give the isocyanide difluoride.^: 45

1 2 R. G. Guy (1977). "Syntheses and Preparative Applications of Thiocyanates". In Saul Patai (ed.). Cyanates and Their Thio Derivatives: Part 2, Volume 2. PATAI'S Chemistry of Functional Groups. p. 619-818. doi:10.1002/9780470771532.ch2. ISBN 9780470771532.
1 2 Ulrich, H. The Chemistry of Imidoyl Halides; Plenum Press: New York, 1968.