title: Acyl cyanide
text: # Acyl cyanide
  
  In organic chemistry, an acyl cyanide is a functional group with the formula R−C(O)CN and structure R−C(=O)−C≡N. It consists of an acyl group (R−C=O) attached to cyanide (−C≡N). Examples include acetyl cyanide, formyl cyanide, and oxalyl dicyanide. Acyl cyanides are reagents in organic synthesis.
  
  ## Synthesis
  
  Classically acyl cyanides are produced by the salt metathesis reaction of acyl chlorides with sodium cyanide:
  
      ${\color {red}{\ce {R-C(O)}}}{\ce {Cl}}+{\ce {Na}}{\color {red}{\ce {CN}}}\longrightarrow {\color {red}{\ce {R-C(O)CN}}}+{\ce {NaCl}}$
  
  Alternatively, they can be produced by dehydration of acyl aldoximes:
  
      ${\color {red}{\ce {R-C(O)C}}}{\ce {H=}}{\color {red}{\ce {N}}}{\ce {OH}}\longrightarrow {\color {red}{\ce {R-C(O)CN}}}+{\ce {H2O}}$
  
  Acetyl cyanide is also prepared by hydrocyanation of ketene:
  
      ${\ce {CH2=}}{\color {red}{\ce {C=O}}}+{\ce {H}}{\color {red}{\ce {CN}}}\longrightarrow {\ce {H3C -}}{\color {red}{\ce {C(O)CN}}}$
  
  ## Reactions
  
  They are mild acylating agents. With aqueous base, acyl cyanides break down to cyanide and the carboxylate:
  
      ${\color {red}{\ce {R-C(O)CN}}}+{\ce {2 NaOH}}\longrightarrow {\color {red}{\ce {R-CO}}}{\ce {_2Na}}+{\ce {Na}}{\color {red}{\ce {CN}}}+{\ce {H2O}}$
  
  With azides, acyl cyanides undergo the click reaction to give acyl tetrazoles.
  
  