Allyl isothiocyanate

Allyl isothiocyanate
IUPAC name 3-Isothiocyanato-1-propene
Other names synthetic mustard oil
Identifiers
CAS number	57-06-7 Y
PubChem	5971
ChemSpider	21105854 Y
UNII	BN34FX42G3 Y
KEGG	D02818 Y
ChEMBL	CHEMBL233248 Y
Jmol-3D images	Image 1
SMILES C=CCN=C=S
InChI InChI=1S/C4H5NS/c1-2-3-5-4-6/h2H,1,3H2 Y Key: ZOJBYZNEUISWFT-UHFFFAOYSA-N Y InChI=1/C4H5NS/c1-2-3-5-4-6/h2H,1,3H2 Key: ZOJBYZNEUISWFT-UHFFFAOYAS
Properties
Molecular formula	C4H5NS
Molar mass	99.15 g mol−1
Density	1.013–1.020 g/cm3
Melting point	−102 °C, 171 K, -152 °F
Boiling point	148-154 °C, 421-427 K, 298-309 °F
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Allyl isothiocyanate (AITC) is the organosulfur compound with the formula CH₂CHCH₂NCS. This colorless oil is responsible for the pungent taste of mustard, horseradish, and wasabi. This pungency and the lachrymatory effect of AITC is mediated through the TRPA1 and TRPV1 ion channels.^[1][2][3] It is slightly soluble in water, but well soluble in most organic solvents.^[4]

Biosynthesis and biological functions

Allyl isothiocyanate comes from the seeds of black mustard (Brassica nigra) or brown Indian mustard (Brassica juncea). When these mustard seeds are broken, the enzyme myrosinase is released and acts on a glucosinolate known as sinigrin to give allyl isothiocyanate.

Allyl isothiocyanate serves the plant as a defense against herbivores; since it is harmful to the plant itself, it is stored in the harmless form of the glucosinolate, separate from the myrosinase enzyme. When an animal chews the plant, the allyl isothiocyanate is released, repelling the animal.

Commercial and other applications

Allyl isothiocyanate is produced commercially by the reaction of allyl chloride and potassium thiocyanate:^[4]

CH₂=CHCH₂Cl + KSCN → CH₂=CHCH₂NCS + KCl.

The product obtained in this fashion is sometimes known as synthetic mustard oil. Allyl isothiocyanate can also be liberated by dry distillation of the seeds. The product obtained in this fashion is known as volatile oil of mustard and is usually around 92% pure. It is used principally as a flavoring agent in foods. Synthetic allyl isothiocyanate is used as an insecticide, bacteriocide, and nematocide, and is used in certain cases for crop protection.^[4]

Hydrolysis of allyl isothiocyanate gives allyl amine.^[5]

Safety

Allyl isothiocyanate is fairly toxic with LD₅₀ of 151 mg/kg and is a dangerous lachrymator.^[4]

References

1. ^ Everaerts, Wouter; Gees, Maarten; Alpizar, Yeranddy A.; Farre, Ricard; Leten, Cindy; Apetrei, Aurelia; Dewachter, Ilse; Van Leuven, Fred et al (2011). "The Capsaicin Receptor TRPV1 is a Crucial Mediator of the Noxious Effects of Mustard Oil". Current Biology 21 (4): 316–21. doi:10.1016/j.cub.2011.01.031. PMID 21315593. 
2. ^ Brône B, Peeters PJ, Marrannes R, Mercken M, Nuydens R, Meert T, Gijsen HJ (September 2008). "Tear gasses CN, CR, and CS are potent activators of the human TRPA1 receptor". Toxicol. Appl. Pharmacol. 231 (2): 150–6. doi:10.1016/j.taap.2008.04.00. PMID 18501939. 
3. ^ Ryckmans T, Aubdool A A, Bodkin J V, Cox P, Brain S D, Dupont T, Fairman E, Hashizume Y, Ishii N, Kato T, Kitching L, Newman J, Omoto K, Rawson D and Strover J (August 2011). "Design and pharmacological evaluation of PF-4840154, a non-electrophilic reference agonist of the TrpA1 channel". Bioorganic. Med. Chem. Lett. 21 (16): 4857–9. doi:10.1016/j.bmcl.2011.06.035. PMID 21741838. 
4. ^ ^{a b c d} F. Romanowski, H. Klenk "Thiocyanates and Isothiocyanates, Organic" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH: Weinheim.
5. ^ M. T. Leffler (1943), "Allylamine", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV2P0024 ; Coll. Vol. 2: 24 

See also

• Piperine, the active piquant chemical in black pepper
• Capsaicin, the active piquant chemical in chili peppers
• Allicin, the active piquant flavor chemical in raw garlic
• List of phytochemicals in food