Allyl isothiocyanate

Allyl isothiocyanate
IUPAC name	3-isothiocyanato-1-propene
Other names	synthetic mustard oil
Identifiers
CAS number	57-06-7 Y
SMILES	C=CC\N=C=S
InChI	1/C4H5NS/c1-2-3-5-4-6/h2H,1,3H2
InChI key	ZOJBYZNEUISWFT-UHFFFAOYAS
ChemSpider ID	5753
Properties
Molecular formula	C4H5NS
Molar mass	99.15 g/mol
Density	1.013–1.020 g/cm3
Melting point	−102 °C
Boiling point	148–154 °C
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Allyl isothiocyanate is the organosulfur compound with the formula CH₂CHCH₂NCS. This colorless oil is responsible for the pungent taste of mustard, horseradish, and wasabi. It is slightly soluble in water, but well soluble in most organic solvents.^[1]

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:^[1]

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.^[1]

Hydrolysis of allyl isothiocyanate gives allyl amine.^[2]

Safety

Allyl isothiocyanate is fairly toxic with LD₅₀ of 151 mg/kg and is a dangerous lachrymator.^[1]

References

1. ^ ^{a b c d} F. Romanowski, H. Klenk "Thiocyanates and Isothiocyanates, Organic" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH: Weinheim.
2. ^ 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 and onions
• List of phytochemicals in food