Mustard_Oils

Mustard Oils, organic chemical compounds of general formula RNCS. They may be prepared by the action of carbon bisulphide on primary amines in alcoholic or ethereal solution, the alkyl dithio-carbamic compounds formed being then precipitated with mercuric chloride, and the mercuric salts heated in aqueous solution, 2R NH2 CS2 CS /NHR HgC12[RHNCS212Hg-)HgS±H2S+2RNCS; -> SNH3R or the isocyanic esters may be heated with phosphorus pentasulphide (A. Michael and G. Palmer, Amer. Chem. Jour., 1884, 6, 257). They are colourless liquids with a very pungent irritating odour. They are readily oxidized, with production of the corresponding amine. Nascent hydrogen converts them into the amine, with simultaneous formation of thio-formaldehyde, [[Rncs+4h=RNh2-1-Hcsh]]. When heated with acids to 100° C, they decompose with formation of the amine and liberation of carbon bisulphide and sulphuretted hydrogen. They combine directly with alcohols, mercaptans, ammonia, amines and with aldehyde ammonia.

Methyl mustard oil, CH 3 NCS, melts at 35° C. and boils at 119° C. Allyl mustard oil, C 3 H 5 NCS, is the principal constituent of the ordinary mustard oil obtained on distilling black mustard seeds. These seeds contain potassium myronate (C10H1sNS2010K) which in presence of water is hydrolysed by the myrosin present in the seed, C10H18NS2010K = C6H1206+[[Khs04+C3h5ncs]].

It may also be prepared by heating ally! sulphide with potassium sulphocyanide. It is a colourless liquid boiling at 1507° C. It combines directly with potassium bisulphite. Phenyl mustard oil, C 6 H 5 NCS, is obtained by boiling sulphocarbanilide with concentrated hydrochloric acid, some triphenylguanidine being formed at the same time. It is a colourless liquid boiling at 222° C. When heated with copper powder it yields benzonitrile.