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Heading 2930 : Organo-sulphur compounds.
This heading includes organo-sulphur compounds whose molecules have sulphur atom(s) directly linked to carbon atom(s) (see Note 6 to this Chapter). It includes compounds whose molecules contain, in addition to sulphur atom(s), other non-metal or metal atom(s) directly linked to carbon atom(s).(A) DITHIOCARBONATES (XANTHATES)
These are diesters or salts of monoesters of dithiocarbonic acid and correspond to the general formula (ROC(S)SRR1) in which R is an organic radical and R1 is a metal (sodium, potassium, etc.) or an organic radical. (1) Sodium ethyldithiocarbonate (ethylxanthate). Amorphous; used to prepare synthetic indigo, and in the flotation of ores. (2) Potassium ethyldithiocarbonate (ethylxanthate). Oily, yellowish crystals; used as a flotation agent for lead and zinc ores, and as an antiparasitic and anticryptogamic agent. (3) Methyl-, butyl-, pentyl- and benzyldithiocarbonates (xanthates). (B) THIOCARBAMATES, DITHIOCARBAMATES
AND THIURAM SULPHIDES (1) Thiocarbamates include the salts and esters of thiocarbamic acid (H2NCOSH or H2NCSOH) (which does not exist in the free state), whether or not hydrogen atoms of the NH2 group are substituted with alkyl or aryl groups. (2) Dithiocarbamates include the salts and esters of dithiocarbamic acid, whether or not hydrogen atoms of the NH2 group are substituted with alkyl or aryl groups. The metal salts of substituted dithiocarbamic acids (e.g., zinc dibutyldithiocarbamate) are used as vulcanisation accelerators in the rubber industry. (3) Thiuram mono-, di- or tetrasulphides. The alkyl substituted derivatives (e.g., tetraethylthiuram disulphide) are used as vulcanisation accelerators. (C) SULPHIDES (OR THIOETHERS)
These may be regarded as ethers in which the oxygen atom is replaced by one of sulphur
(ROR1) ether ...................... (RSR1) sulphide (1) Methionine. White platelets or powder. An amino acid. Essential component in human nutrition, not synthesised by the body. (2) Dimethyl sulphide, diphenyl sulphide. Colourless liquids with a very disagreeable odour. (3) Thiodiglycol or bis(2-hydroxyethyl)sulphide; a liquid used as a solvent for dyes in textile printing. (4) Thioaniline or 4,4'-diaminodiphenyl sulphide. (D) THIOAMIDES (1) Thiourea (H2NCSNH2) is the diamide of thiocarbonic acid and is thus the sulphur analogue of urea. Lustrous, white crystals. Used in photography, as an auxiliary in dyeing, and for preparing intermediate compounds in the dyestuff and pharmaceutical industries. (2) Thiocarbanilide (diphenylthiourea). Colourless, crystalline tablets or amorphous white powder. Used for preparing intermediate compounds in the dyestuffs industry (sulphur dyes, indigo) and synthetic pharmaceutical products; also as an accelerator in the vulcanisation of rubber, and for the flotation of ores. (3) Di-o-tolylthiourea. White powder, insoluble in water; used as an accelerator in the vulcanisation of rubber. (E) THIOLS (MERCAPTANS)
These sulphur compounds correspond to alcohols or phenols in which the oxygen atoms have been replaced by sulphur atoms.
(ROH) alcohol or phenol ...................... (RSH) mercaptan (1) Thioalcohols, like alcohols, may be primary, secondary or tertiary, containing the groups (-CH2SH), (CHSH) or (CSH), respectively.
They are generally colourless or yellowish liquids with a disagreeable odour. (a) Methanethiol (methyl mercaptan). (b) Ethanethiol (ethyl mercaptan). (c) Butanethiol (butyl mercaptan). (d) Pentanethiol (pentyl mercaptan). (2) Thiophenols. (a) Thiophenol (C6H5SH) (b) o-Mercaptobenzoic acid, sometimes described as thiosalicylic acid. (F) THIOALDEHYDES
General formula (RCSH). (G) THIOKETONES
General formula (RCSR1). (H) THIOACIDS
General formula (RCOSH or RCSOH and also RCSSH).
An example is dithiosalicylic acid (HOC6H4CSSH), but this name is often applied to the compound di(o-carboxyphenyl) disulphide. (IJ) SULPHINIC ACIDS, SULPHOXIDES AND SULPHONES
These have the general formulae (RSO2H), (RSOR1) and (RSO2R1), respectively.
An example is sulphonal, colourless crystals, used in medicine. (K) ISOTHIOCYANATES
General formula (RN=CS).
They may be regarded as the "esters" of isothiocyanic acid. They include ethyl isothiocyanate; phenyl isothiocyanate; allyl isothiocyanate (or artificial mustard oil).
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