Amyl nitrite

Amyl nitrite

Amyl nitrite is the chemical compound with the formula C5H11ONO. A variety of isomers are known, but they all feature an amyl group attached to the nitrito functional group. The alkyl group is unreactive and the chemical and biological properties are mainly due to the nitrite group. Like other alkyl nitrites, amyl nitrite is bioactive in mammals, being a vasodilator which is the basis of its use as a prescription medicine. As an inhalant, it also has a psychoactive effect which has led to its recreational use.

Nomenclature

The term "amyl nitrite" encompasses several isomers. For example, a common form of amyl nitrite with the formula (CH3)2CHCH2CH2ONO may be more specifically referred to as isoamyl nitrite. When the amyl group is a linear or normal (n) alkyl group, the resulting amyl nitrite would have the structural formula CH3(CH2)4ONO.

Amyl nitrite is often confused with amyl nitrate, a substance with a different chemical composition and different properties.

Synthesis and reactions

Alkyl nitrites are prepared by the reaction of alcohols with nitrous acid:
C5H11OH + HONO → C5H11ONO + H2O
The reaction is called esterification. Synthesis of alkyl nitrites is generally straightforward and can be accomplished in home laboratories. A common procedure includes the dropwise addition of concentrated sulfuric acid to a cooled mixture of an aqueous sodium nitrite solution and an alcohol. The intermediately formed stoichiometric mixture of nitrous and nitric oxide then converts the alcohol to the alkyl nitrite, which, due to its low density, will form an upper layer that can be easily decanted from the reaction mixture.

Isoamyl nitrite decomposes in the presence of base to give nitrite salts and the isoamyl alcohol:

C5H11ONO + NaOH → C5H11OH + NaNO2

Amyl nitrite, like other alkyl nitrites, reacts with carbanions to give oximes.

Physiological effects

Amyl nitrite, in common with other alkyl nitrites, is a potent vasodilator, i.e. it expands blood vessels, resulting in lowering of the blood pressure. Alkyl nitrites function as a source of nitrous oxide, which signals for relaxation of the involuntary muscles. Physical effects include decrease in blood pressure, headache, flushing of the face, increased heart rate, dizziness, and relaxation of involuntary muscles, especially the blood vessel walls and the anal sphincter. There are no withdrawal symptoms. Overdose symptoms include nausea, emesis (vomiting), hypotension, hypoventilation, dyspnea (shortness of breath), and syncope (fainting). The effects set in very quickly, typically within a few seconds and disappearing soon after (within a minute).

It induces the formation of methemoglobin, which sequesters cyanide as non-toxic cyanomethemoglobin.

Applications

Amyl nitrite is employed medically to treat heart diseases such as angina and to treat cyanide poisoning. It is also used as an inhalant drug that induces a brief euphoria; whilst already intoxicated with stimulant drugs such as cocaine or ecstasy (see MDMA) the euphoric state intensifies and lasts for several minutes longer. Once some stimulative drugs wear off, a common side effect is a period of depression or anxiety, colloquially called a "come down"; amyl nitrite is sometimes used to "come up" again in order to stop the user from feeling lousy. This drug is often used to obtain an erection with rather rapid onset. This effect, combined with its dissociative effects, makes it an attractive but risky recreational drug. See Poppers.

References

External links

  • Abstract for an article in the Journal of Chemical Education (1996, volume 73, page 1127) by Richard A. Kjonaas on the use of the word "amyl".

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