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Allyl cyanide

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Allyl cyanide
Structural formula of allyl cyanide
Ball-and-stick model of the allyl cyanide molecule
Names
Systematic IUPAC name
3-Butenenitrile
Identifiers
3D model (JSmol)
605352
ChemSpider
ECHA InfoCard 100.003.366 Edit this at Wikidata
EC Number
  • 203-701-1
  • Key: SJNALLRHIVGIBI-UHFFFAOYSA-N
  • C=CCC#N
Properties
C4H5N
Molar mass 67.091 g·mol−1
Appearance colourless liquid
Density 0.834 g/cm3[1]
Melting point −87 °C (−125 °F; 186 K)
Boiling point 116 to 121 °C (241 to 250 °F; 389 to 394 K)[1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Flammable, poison, irritates skin and eyes
Ingestion hazards
 Toxic if swallowed.
Inhalation hazards
 May be fatal if inhaled. Causes respiratory tract irritation.
Eye hazards
 Causes eye irritation.
Skin hazards
 Causes skin irritation.
GHS labelling:
GHS02: Flammable GHS06: Toxic
Danger
H226 H301 H315 H312 H319 H311
P280 P261 P305+P351+P338 P301+P310 P311
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
4
3
0
Flash point 24 °C (75 °F; 297 K)[1]
455 °C (851 °F; 728 K)[1]
Safety data sheet (SDS) MSDS
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Allyl cyanide is an organic compound with the formula CH2CHCH2CN. Like other small alkyl nitriles, allyl cyanide is soluble in organic solvents. Allyl cyanide occurs naturally as an antifeedant and is used as a cross-linking agent in some polymers.[3] Allyl cyanide was discovered in 1863 by H. Will and W. Koerner in 1863, they found the compound to be present in mustard oil.[4] The first successful synthesis of allyl cyanide was done by A. Claus in 1864.[5] Recent studies show that 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.[6]

Synthesis

Allyl cyanide can be prepared by treating allyl bromide with copper(I) cyanide under rigorous heating. This reaction follows a classical SN2 reaction, where the cyanide anion of the copper(I) complex acts as a nucleophile to replace the bromide from the allyl bromide.[7]

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.[8]

Another way to gain allyl cyanide is to use rat intestinal microbiota. By adding sinigrin to rat intestinal microbiota and subsequent incubation under anaerobe conditions, this will lead to desulfosinigrin. Further incubation yields allyl cyanide as the major degradation product. More degradation products are isothiocyanate and 1-cyano-2,3-epithiopropane. The exact working principle is not yet understood, but it is suggested that intestinal microbiota may utilize thioglucosidase for this reaction.[9]

Natural occurrences

Allyl cyanide is produced in cruciferous vegetables by myrosinase, an enzyme which hydrolyses glucosinolates to form nitriles and other products.[10] Myrosinase is activated by l-ascorbic acid (vitamin C) under the influence of the pH,[11] 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.[12] 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.[10] 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.

Neurotoxicity

Studies performed on rats showed that allyl cyanide cause loss of hair cells in the auditory system and troubling of the cornea.[13] 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.[14] Studies done with mice showed that a single (albeit rather high) dose of allyl cyanide can cause permanent behavioural changes.[15] 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.[16]

Toxicokinetics

Allyl cyanide is known to be metabolized in the liver by the Cytochrome P-450 enzyme system to cyanide.[17] 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.[18] Major routes of excretion are through the urine and expired air.

Toxicodynamics

Allyl cyanide belongs to the family of aliphatic nitriles that are potentially toxic compounds causing depletion of glutathione in rats. Furthermore, allyl cyanide induces long-term dyskinesia in mice after a single dosage.[19] 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.[20] Ataxia, trembling, convulsions, diarrhea, salivation, lacrimation and irregular breathing are known effects that are caused by oral ingestion of allyl cyanide.

References

  1. ^ a b c d MSDS
  2. ^ Lide, David R., W. M. Haynes, and Thomas J. Bruno, eds. CRC Handbook of Chemistry and Physics. 93rd ed. Boca Raton, FL: CRC, 2012. Web. 17 Oct. 2012.
  3. ^ http://encyclopedia2.thefreedictionary.com/allyl+cyanide
  4. ^ C. Pomeranz: "Ueber Allylcyanid und Allylsenföl", in: Justus Liebigs Annalen der Chemie, 1906, 351 (1–3), P. 354–362: doi:10.1002/jlac.19073510127
  5. ^ A. Claus: "Ueber Crotonsäure", in: Justus Liebigs Annalen der Chemie, 1864, 131 (1), P. 58–66;doi:10.1002/jlac.18641310106
  6. ^ L. Zhang et al. Allyl cyanide as a new functional additive in propylene carbonate-based electrolyte for lithium-ion batteries Iconics August 2013, Volume 19, Issue 8, pp 1099-1103
  7. ^ J. V. Supniewski; P. L. Salzberg. "Allyl Cyanide". Organic Syntheses; Collected Volumes, vol. 1, p. 46.
  8. ^ A. Rinne, B. Tollens: "Ueber das Allylcyanür oder Crotonitril", in: Justus Liebigs Annalen der Chemie, 1871, 159 (1), S. 105–109; doi:10.1002/jlac.18711590110
  9. ^ Meng Lua, Kei Hashimotob, Yasushi Udab, Corresponding author contact information Volume 44, Issue 4, May 2011, Pages 1023–1028
  10. ^ a b 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
  11. ^ L.G. West et al. Allyl Isothiocyanate and Allyl Cyanide Production in Cell-Free Cabbage Leaf Extracts, Shredded Cabbage, and Cole Slaw / J. Agric. Food Chem. Vol. 25, No. 6, (1997), 1234-1238
  12. ^ C. Krul et al. Metabolism of sinigrin (2-propenyl glucosinolate) by the human colonic microflora in a dynamic in vitro large-intestinal model / Carcinogenesis, Vol. 24, No. 6, (2002), 1009-1016
  13. ^ E. Balbuena, J. Llorens Behavioural disturbances and sensory pathology following allylnitrile exposure in rats / Brain Research 904 (2001) 298-306
  14. ^ C. Soler-Martín et al. Butenenitriles have low axonopathic potential in the rat / Toxicology Letters 200 (2011) 187-193
  15. ^ Xiao-ping Zang et al. Behavioral abnormalities and apoptotic changes in neurons in mice brain following a single administration of allylnitrile / Arch Toxicol 73 (1999) 22-32
  16. ^ 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.
  17. ^ A. E. Ahmed and M. Y. H. Farooqui: Comparative toxicities of aliphatic nitriles. Toxicol. Len. 12, 157-163 (1982)
  18. ^ E. Ahmed, M. Y. H. Farooqui, and N. M. Tneff: Nitriles. In:“Biotransformation of Foreign Compounds” (M. W. Anders, ed), pp. 485-510. Academic Press, New York, 1985.
  19. ^ Y. H. Farooqui, B. Ybarra, J. Piper: Toxicokinetics of allyl nitrile in rats 21(3): 460-466 (1992)
  20. ^ 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)
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