In organic chemistry, alkyl nitrites are a group of based upon the molecular structure , where R represents an alkyl group. Formally they are alkyl of nitrous acid. They are distinct from ().
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 (3-methylbutyl nitrite).
Alkyl nitrites were initially, and largely still are, used as and , a practice which began in the late 19th century. In their use as medicine, they are often inhaled for relief of angina and other heart-related symptoms of disease. However, when referred to as " poppers", alkyl nitrites represent recreational drugs.
Synthesis and properties
Organic nitrites are prepared from alcohols and
sodium nitrite in
sulfuric acid solution. They decompose slowly on standing, the decomposition products being
of
nitrogen,
water, the alcohol, and
polymerization products of the
aldehyde.
[ n-butyl nitrite Organic Syntheses, Coll. Vol. 2, p.108 (1943); Vol. 16, p.7 (1936). http://www.orgsynth.org/orgsyn/prep.asp?prep=cv2p0108 Link] They are also prone to undergo homolytic cleavage to form alkyl radicals, the nitrite C–O bond being very weak (on the order of 40–50 kcal ⋅ mol
−1). Alkyl nitrites are generally weak
nitrosation, but nitrosate amines in the presence of a nucleophile catalyst.
Reactions
-
tert-Butyl nitrite has been shown to be an effective reagent for the selective nitration of phenols
[ Chemoselective Nitration of Phenols with tert-Butyl Nitrite in Solution and on Solid Support Organic Letters, Coll. Vol 11, p.4172-4175 (2009)] and aryl sulfonamides[ Chemoselective Nitration of Aromatic Sulfonamides with tert-Butyl Nitrite Chemical Communications, ]
-
Butyl nitrite and ammonia convert phenylhydroxylamine to its nitrosamine derivative cupferron.
[ Cupferron Organic Syntheses, Coll. Vol. 1, p.177 (1941); Vol. 4, p.19 (1925) Link] Likewise pyrrolidine is a substrate for ethyl nitrite.[ 2-Pyrrolidinemethanol, α,α-diphenyl-, (±)- Organic Syntheses, Coll. Vol. 6, p.542 (1988); Vol. 58, p.113 (1978) Link]
-
Alkyl nitrites are also used in the formation of with the stronger and acid or base catalysis for example in the reaction of 2-butanone, ethyl nitrite and hydrochloric acid forming the oxime,
[ Dimethylglyoxime Organic Syntheses, Coll. Vol. 2, p.204 (1943); Vol. 10, p.22 (1930) Link] the similar reaction with phenacyl chloride,[ Glyoxylyl chloride, phenyl-, oxime Organic Syntheses, Coll. Vol. 3, p.191 (1955); Vol. 24, p.25 (1944) Link] or the reaction of phenylacetonitrile with methyl nitrite and sodium hydroxide.
An isolated but classic example of the use of alkyl nitrites can be found in Woodward and Doering's quinine total synthesis:[ The Total Synthesis of Quinine R. B. Woodward and W. E. Doering J. Am. Chem. Soc.; 1945; 67(5) pp 860 - 874; ]
for which they proposed this reaction mechanism:
External links
