organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

, isothiocyanate is a

functional group In organic chemistry, a functional group is any substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions r ...

as found in compounds with the formula . Isothiocyanates are the more common isomers of thiocyanates, which have the formula .

Occurrence

Many isothiocyanates from plants are produced by enzymatic conversion of metabolites called glucosinolates. A prominent natural isothiocyanate is allyl isothiocyanate, also known as mustard oils. Cruciferous vegetables, such as bok choy,

broccoli Broccoli (''Brassica oleracea'' var. ''italica'') is an edible green plant in the Brassicaceae, cabbage family (family Brassicaceae, genus ''Brassica'') whose large Pseudanthium, flowering head, plant stem, stalk and small associated leafy gre ...

, cabbage, cauliflower, kale, and others, are rich sources of glucosinolate precursors of isothiocyanates.

Structure

The and distances are 117 and 158 pm. By contrast, in methyl thiocyanate, and distances are 116 and 176 pm. Typical bond angles for in aryl isothiocyanates are near 165°. Again, the thiocyanate isomers are quite different with angle near 100°. In both isomers the angle approaches 180°.

Synthesis

Allyl thiocyanate isomerizes to the isothiocyanate: : Isothiocyanates can be prepared by treating organic dithiocarbamate salts with lead nitrate or tosyl chloride. : Synthesis phenylisothiocyanate 1

Isothiocyanates may also be accessed by the fragmentation reactions of 1,4,2-oxathiazoles. This methodology has been applied to a polymer-supported synthesis of isothiocyanates.

Reactions

Isothiocyanates are weak electrophiles, susceptible to hydrolysis. In general, nucleophiles attack at carbon: Electrochemical reduction gives thioformamides.

Flavor research

Isothiocyanates occur widely in nature and are of interest in food science and

medical research Medical research (or biomedical research), also known as health research, refers to the process of using scientific methods with the aim to produce knowledge about human diseases, the prevention and treatment of illness, and the promotion of ...

. Vegetable foods with characteristic flavors due to isothiocyanates include bok choy,

, cabbage, cauliflower, kale, wasabi, horseradish, mustard, radish, Brussels sprouts, watercress, papaya seeds, nasturtiums, and capers. These species generate isothiocyanates in different proportions, and so have different, but recognizably related, flavors. They are all members of the order

Brassicales The Brassicales (or Cruciales) are an order (biology), order of flowering plants, belonging to the malvid group of eudicotyledons under the APG IV system. Well-known members of Brassicales include cabbage, cauliflower, Brussels sprout, broccoli, ...

, which is characterized by the production of glucosinolates, and of the enzyme myrosinase, which acts on glucosinolates to release isothiocyanates. * Sinigrin is the precursor to allyl isothiocyanate * Glucotropaeolin is the precursor to benzyl isothiocyanate * Gluconasturtiin is the precursor to phenethyl isothiocyanate * Glucoraphanin is the precursor to sulforaphane

Uses

Phenyl isothiocyanate, is used for

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

sequencing in the Edman degradation.

Coordination chemistry

Isothiocyanate and its linkage isomer thiocyanate are ligands in coordination chemistry. Thiocyanate is a more common

ligand In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...

References

{{Authority control Antioxidants Functional groups Isothiocyanates Oncology Phytochemicals