acyl cyanide

File:Acyl cyanide.svg

In organic chemistry, an acyl cyanide is a functional group with the formula {{chem2|R\sC(O)CN}} and structure {{chem2|R\sC(\dO)\sC\tN}}. It consists of an acyl group ({{chem2|R\sC\dO}}) attached to cyanide ({{chem2|\sC\tN}}). Examples include acetyl cyanide, formyl cyanide, and oxalyl dicyanide. Acyl cyanides are reagents in organic synthesis.{{cite journal |doi=10.1021/acs.orglett.8b01180|title=Stereoselective Synthesis of Fully-Substituted Acrylonitriles via Formal Acylcyanation of Electron-Rich Alkynes|year=2018|last1=Liu|first1=Bing|last2=Wang|first2=Yong|last3=Chen|first3=Ying|last4=Wu|first4=Qian|last5=Zhao|first5=Jing|last6=Sun|first6=Jianwei|journal=Organic Letters|volume=20|issue=12|pages=3465–3468|pmid=29873500|s2cid=46942109}}{{cite book |doi=10.1002/047084289X.ra026|chapter=Acetyl Cyanide|title=Encyclopedia of Reagents for Organic Synthesis|year=2001|last1=Morris|first1=Joel|isbn=0471936235}}

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:{{cite journal |doi=10.1002/anie.198200361|title=The Chemistry of Acyl Cyanides|year=1982|last1=Hünig|first1=Siegfried|last2=Schaller|first2=Rainer|journal=Angewandte Chemie International Edition in English|volume=21|pages=36–49}}

: ${\color{red}\ce{R-C(O)CN}} + \ce{2 NaOH} \longrightarrow {\color{red}\ce{R-CO}}\ce{_2Na} + \ce{Na}{\color{red}\ce{CN}} + \ce{H2O}$

With azides, acyl cyanides undergo the click reaction to give acyl tetrazoles.{{cite journal |doi=10.1002/1521-3773(20020617)41:12<2113::AID-ANIE2113>3.0.CO;2-Q|title=A Click Chemistry Approach to Tetrazoles by Huisgen 1,3-Dipolar Cycloaddition: Synthesis of 5-Acyltetrazoles from Azides and Acyl Cyanides|year=2002|last1=Demko|first1=Zachary P.|last2=Sharpless|first2=K. Barry|journal=Angewandte Chemie International Edition|volume=41|issue=12|pages=2113–2116|pmid=19746613}}

References

Category:Functional groups

Category:Organic compounds