|Other names||Isoamyl nitrite, nitramyl, 3-methyl-1-nitrosooxybutane, pentyl alcohol nitrite (ambiguous), poppers, banapple gas|
|Onset of action||Within 30 sec|
|Duration of action||About 4 min|
|Chemical and physical data|
|Molar mass||117.148 g·mol−1|
|3D model (JSmol)|
|Boiling point||99 °C (210 °F)|
|Solubility in water||Slightly soluble mg/mL (20 °C)|
Amyl nitrite is a chemical compound and medication. As a medication it has been used for heart related chest pain and cyanide poisoning. For chest pain nitroglycerin is now generally used instead. It is also used recreational by inhalation with claims that it makes a person high and improves sexual function. Effects begin within 30 seconds and last about 4 minutes.
Common side effects may include headache, flushing of the skin, and lightheadedness. Other side effects may include fainting, lose of bladder control, low blood pressure, and nausea. Large doses may result in methemoglobinemia. Tolerance to its effects may occur with withdrawal after it is stopped. It is a yellow liquid with a smell that has been described as fruity. Medically it works by dilating blood vessels.
Amyl nitrite was first documented in 1844 and came into medical use in 1867. It was available as a generic medication; however, is no longer approved for medical use in the United States. It came into common recreational use in the 1960s particularly by the gay community in the United States. Common street names include "poppers" and "pearls". Butyl nitrite and isobutyl nitrite are sometimes sold claiming to be amyl nitrite for recreational use.
- Amyl nitrite is employed medically to treat angina.
- Amyl nitrite is sometimes used as an antidote for cyanide poisoning. It can act as an oxidant, to induce the formation of methemoglobin. Methemoglobin in turn can sequester cyanide as cyanomethemoglobin.
It is also used recreationally as an inhalant drug that induces a brief euphoric state, and when combined with other intoxicant stimulant drugs such as cocaine or MDMA, the euphoric state intensifies and is prolonged. 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 combat these negative after-effects. This effect, combined with its dissociative effects, has led to its use as a recreational drug (see poppers).
Amyl nitrite is used as a cleaning agent and solvent in industrial and household applications. It replaced dichlorodifluoromethane, an industrial chemical universally banned in 1996 due to damage to the ozone layer, as a printed circuit board cleaner. Trace amounts are added to some perfumes.
Significant acute toxicity principally results from methaemoglobinaemia. Contaminated haemoglobin, methaemoglobin, prevents red cells from carrying oxygen. The patient has a blueish appearance. Treatment in severe cases is with intravenous methylene blue which rather alarmingly turns the patient even more blue, though is in fact very effective in clearing the methaemoglobin.
The extent of impaired oxygen carrying capacity and subsequent tissue hypoxia is not evident on routine investigations. Pulse oximetry grossly exaggerates the oxygen carrying capacity of methaemoglobin. Arterial blood gas analysis also assumes all haemoglobin present has the capacity to carry oxygen. Thankfully arterial and venous blood gas samples are reported with a percentage of methaemoglobin in the emergency departments of the UK.
Mechanism of action
A variety of isomers are known, but they all feature an amyl group attached to the nitrite 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.
Amyl nitrite, in common with other alkyl nitrites, is a potent vasodilator; it expands blood vessels, resulting in lowering of the blood pressure. Amyl nitrite may be used during cardiovascular stress testing in patients with suspected hypertrophic cardiomyopathy to cause vasodilation and thereby reduce afterload and provoke a left ventricular outflow tract obstruction[clarification needed] by increasing the pressure gradient. Alkyl nitrites are a source of nitric 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 internal and external anal sphincter. There are no withdrawal symptoms. Overdose symptoms include nausea, vomiting, hypotension, hypoventilation, shortness of breath, and fainting. The effects set in very quickly, typically within a few seconds and disappear within a few minutes. Amyl nitrite may also intensify the experience of synesthesia.
Synthesis and reactions
- ROH + HONO → RONO + H2O, where R = alkyl group
The reaction is called esterification. Synthesis of alkyl nitrites is, in general, 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 nitrogen dioxide 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 nitrites are also useful as reagents in a modification of the Sandmeyer reaction. The reaction of the alkyl nitrite with an aromatic amine in a halogenated solvent produces a radical aromatic species, this then frees a halogen atom from the solvent. For the synthesis of aryl iodides diiodomethane is used, whereas bromoform is the solvent of choice for the synthesis of aryl bromides.
The term "amyl nitrite" encompasses several isomers. In older literature, the common non-systematic name "amyl" was often used for the pentyl group, where the amyl group is a linear or normal (n) alkyl group, and the resulting amyl nitrite would have the structural formula CH3(CH2)4ONO, also referred to as n-amyl nitrite.
A common form of amyl nitrite is the isomer with the formula (CH3)2CHCH2CH2ONO, which may be more specifically referred to as isoamyl nitrite.
It is also referred to as banapple gas.
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