Chemical group (–C(O)C≡N)
General chemical structure of an 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 .[ 1] [ 2]
Synthesis
Classically acyl cyanides are produced by the salt metathesis reaction of acyl chlorides with sodium cyanide :
R
− − -->
C
(
O
)
Cl
+
Na
CN
⟶ ⟶ -->
R
− − -->
C
(
O
)
CN
+
NaCl
{\displaystyle {\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 :
R
− − -->
C
(
O
)
C
H
=
N
OH
⟶ ⟶ -->
R
− − -->
C
(
O
)
CN
+
H
2
O
{\displaystyle {\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 :
CH
2
=
C
=
O
+
H
CN
⟶ ⟶ -->
H
3
C
− − -->
C
(
O
)
CN
{\displaystyle {\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.[ 2] carboxylate :[ 3]
R
− − -->
C
(
O
)
CN
+
2
NaOH
⟶ ⟶ -->
R
− − -->
CO
Na
2
+
Na
CN
+
H
2
O
{\displaystyle {\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 .[ 4]
References
^ Liu, Bing; Wang, Yong; Chen, Ying; Wu, Qian; Zhao, Jing; Sun, Jianwei (2018). "Stereoselective Synthesis of Fully-Substituted Acrylonitriles via Formal Acylcyanation of Electron-Rich Alkynes". Organic Letters . 20 (12): 3465–3468. doi :10.1021/acs.orglett.8b01180 . PMID 29873500 . S2CID 46942109 . ^ a b Morris, Joel (2001). "Acetyl Cyanide". Encyclopedia of Reagents for Organic Synthesis . doi :10.1002/047084289X.ra026 . ISBN 0471936235 ^ Hünig, Siegfried; Schaller, Rainer (1982). "The Chemistry of Acyl Cyanides". Angewandte Chemie International Edition in English . 21 : 36–49. doi :10.1002/anie.198200361 . ^ Demko, Zachary P.; Sharpless, K. Barry (2002). "A Click Chemistry Approach to Tetrazoles by Huisgen 1,3-Dipolar Cycloaddition: Synthesis of 5-Acyltetrazoles from Azides and Acyl Cyanides". Angewandte Chemie International Edition . 41 (12): 2113–2116. doi :10.1002/1521-3773(20020617)41:12<2113::AID-ANIE2113>3.0.CO;2-Q . PMID 19746613 . 
