Isocyanide dichloride explained

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:^[1]

RN=C=S + 2Cl₂ → RN=CCl₂ + SCl₂Alkylisocyanates 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

References

1. Book: Cyanates and Their Thio Derivatives: Part 2, Volume 2 . Saul Patai. 1977. Syntheses and Preparative Applications of Thiocyanates . R. G. Guy. 10.1002/9780470771532.ch2. PATAI'S Chemistry of Functional Groups. 619-818. 9780470771532 .