Alkyl nitrites

This article is about alkyl nitrites as a laboratory reagent. For their use in medicine and as a recreational drug, see nitrite inhalants.

Alkyl nitrites are chemical compounds of structure R-ONO. Formally they are alkyl esters of nitrous acid.

The first few members of the series are volatile liquids; methyl nitrite and ethyl nitrite are gaseous at room temperature and pressure. The compounds have a distinctive fruity odor. Another frequently encountered nitrite is amyl nitrite.

[edit] Synthesis

Organic nitrites are prepared from alcohols and sodium nitrite in sulfuric acid solution. They decompose slowly on standing, the decomposition products being oxides of nitrogen, water, the alcohol, and polymerization products of the aldehyde.^[1]

In the laboratory, solutions of alkyl nitrites in glacial acetic acid are sometimes used as mild nitrating agents. The nitrating species formed is acetyl nitrate generated in situ.
n-Butyl nitrite and ammonia convert phenylhydroxylamine to its nitrosamine derivative cupferron ^[2]. Likewise pyrrolidine is a substrate for ethyl nitrite ^[3] .
Alkyl nitrites are also used in the formation of oximes with the stronger carbon acids and acid or base catalysis for example in the reaction of 2-butanone, ethyl nitrite and hydrochloric acid forming the oxime ^[4], the similar reaction with phenacyl chloride ^[5]. or the reaction of phenylacetonitrile with methyl nitrite and sodium hydroxide ^[6].

An isolated but classic example of the use of alkyl nitrites can be found in Woodward's and Doering's quinine total synthesis ^[7]:

for which they proposed this reaction mechanism:

^ n-butyl nitrate Organic Syntheses, Coll. Vol. 2, p.108 (1943); Vol. 16, p.7 (1936). http://www.orgsynth.org/orgsyn/prep.asp?prep=cv2p0108 Link
^ Cupferron Organic Syntheses, Coll. Vol. 1, p.177 (1941); Vol. 4, p.19 (1925) Link
^ 2-Pyrrolidinemethanol, α,α-diphenyl-, (±)- Organic Syntheses, Coll. Vol. 6, p.542 (1988); Vol. 58, p.113 (1978) Link
^ Dimethylglyoxime Organic Syntheses, Coll. Vol. 2, p.204 (1943); Vol. 10, p.22 (1930) Link
^ Glyoxylyl chloride, phenyl-, oxime Organic Syntheses, Coll. Vol. 3, p.191 (1955); Vol. 24, p.25 (1944) Link
^ Benzeneacetonitrile, α-[[[(1,1-dimethylethoxy)carbonyl]carbonyl]oxy]imino] Organic Syntheses, Coll. Vol. 6, p.199 (1988); Vol. 59, p.95 (1979) Link
^ The Total Synthesis of Quinine R. B. Woodward and W. E. Doering J. Am. Chem. Soc.; 1945; 67(5) pp 860 - 874; DOI:10.1021/ja01221a051