Allyl cyanide is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the formula CH₂CHCH₂CN. Like other small alkyl nitriles, allyl cyanide is colorless and soluble in organic solvents. Allyl cyanide occurs naturally as an

antifeedant Antifeedants are organic compounds produced by plants to repel herbivores through distaste or toxicity. These chemical compounds are typically classified as secondary metabolites in that they are not essential for the metabolism of the plant, but ...

and is used as a cross-linking agent in some polymers.

Synthesis

Allyl cyanide is obtained by the reaction of allyl acetate with hydrogen cyanide. A laboratory route to allyl cyanide involves treating allyl bromide with

copper(I) cyanide Copper(I) cyanide (cuprous cyanide) is an inorganic compound with the formula CuCN. This off-white solid occurs in two polymorphs; impure samples can be green due to the presence of Cu(II) impurities. The compound is useful as a catalyst, in ele ...

. :CH₂=CHCH₂Br + CuCN → CH₂=CHCH₂CN + CuBr Other allyl halides may be used for this reaction including allyl iodide as done by A. Rinne and B. Tollens in 1871 where iodide is a better leaving group than its bromide equivalent and therefore increases the yield.

Natural occurrences

Allyl cyanide was discovered in 1863 by H. Will and W. Koerner in 1863, they found the compound to be present in

mustard oil Mustard oil can mean either the pressed oil used for cooking or a pungent essential oil, also known as volatile oil, of the mustard plant. The essential oil results from grinding mustard seed, mixing the grounds with water, and isolating the resu ...

. The first synthesis of allyl cyanide was reported by A. Claus in 1864. Allyl cyanide is produced in

cruciferous vegetables Cruciferous vegetables are vegetables of the family Brassicaceae (also called Cruciferae) with many genera, species, and cultivars being raised for food production such as cauliflower, cabbage, kale, garden cress, bok choy, broccoli, Brusse ...

by myrosinase, an enzyme which hydrolyses

glucosinolates Glucosinolates are natural components of many pungent plants such as mustard, cabbage, and horseradish. The pungency of those plants is due to mustard oils produced from glucosinolates when the plant material is chewed, cut, or otherwise dama ...

to form nitriles and other products.H. Tanii et al. Allylnitrile: generation from cruciferous vegetables and behavioral effects on mice of repeated exposure / Food and Chemical Toxicology, 42, (2004), 453-458 Myrosinase is activated by l-ascorbic acid (vitamin C) under the influence of the pH, and higher myrosinase activity has been shown in damaged cabbage leaves, while its activity is reduced by cooking the leaves, although the glucosinolates can then be transformed to allyl cyanide by microflora in the intestines. As cruciferous vegetables like cabbage, broccoli, cauliflower and sprouts are part of the human diet, allyl cyanide is normally consumed orally. The normal dose of allyl cyanide contained in a meal is shown to be much lower than the doses used in animal studies. The daily level at which behavioural effects were demonstrated is 500 μg/kg bodyweight, whereas the daily human consumption amounts to 0.12 μg/kg. Although the dose-response relationship is still to be examined, it is therefore thought that allyl cyanide has no potency as a neurotoxicant when consumed in vegetables.

Applications

Allyl cyanide may be used as an additive in propylene carbonate-based electrolytes for graphite anodes preventing exfoliation of the anode by film-forming. The underlying mechanism is thought to be a reductive polymerization mechanism.

Neurotoxicity

Studies performed on rats showed that allyl cyanide cause loss of hair cells in the auditory system and troubling of the cornea. The same study also showed that the rearing activity of rats was reduced by oral ingestion of allyl cyanide. It has these neurotoxic symptoms in common with other aliphatic mononitriles such as 2-butenenitrile and 3,3'-iminopropionitrile. Allyl cyanide was also shown to cause a swelling of the axons. Studies done with mice showed that a single (albeit rather high) dose of allyl cyanide can cause permanent behavioural changes. These changes include twitching of the head, an increased locomotor activity and circling. These mice were furthermore shown to suffer from neuronal contractions, possibly leading to cell death. Sheep are far more tolerant to the toxic effects of allyl cyanide than rats. Studies suggest that this detoxification is due to the predigestion in the

rumen The rumen, also known as a paunch, is the largest stomach compartment in ruminants. The rumen and the reticulum make up the reticulorumen in ruminant animals. The diverse microbial communities in the rumen allows it to serve as the primary si ...

.Duncan, A. J. and Milne, J. A. (1992), Rumen microbial degradation of allyl cyanide as a possible explanation for the tolerance of sheep to brassica-derived glucosinolates. J. Sci. Food Agric., 58: 15–19.

Toxicokinetics

Allyl cyanide is known to be metabolized in the liver by the Cytochrome P-450 enzyme system (mainly CYP2E1) to cyanide. The absorption and distribution of allyl cyanide in rats is extraordinary fast. The highest concentrations of allyl cyanide were measured in the stomach tissue and stomach contents due to the fact that the stomach is the principal site of absorption after oral administration. The next highest concentration levels were found to be in the bone marrow with a peak in concentration between 0 and 3 hours after administration. The liver, kidneys, spleen and lungs also accumulated allyl cyanide over the course of 48 hours. The highest concentration in the kidney was observed between 3 and 6 hr after dosing. This observation indicates rapid elimination of allyl cyanide. The major route of detoxification is the conversion from cyanide to thiocyanate. Major routes of excretion are through the urine and expired air. The serotonin and dopamine systems are thought to be involved in the behavioral abnormalities caused by allyl cyanide. Treatment by serotonin and dopamine antagonists caused a reduction in the behavioral abnormalities.H. Tanii, Y. Kurosaka, M. Hayashi, and K. Hashimoto: Allylnitrile: a compound which induces long-term dyskinesia in mice following a single administration. Exp. Neurol. 103, 64-67 (1989) Ataxia, trembling, convulsions, diarrhea, salivation, lacrimation and irregular breathing are known effects that are caused by oral ingestion of allyl cyanide.

References

Nitriles Allyl compounds