Xanthate usually refers to a salt with the formula ROCS2−M+ (R = alkyl; M+ = Na+, K+).〔IUPAC does not recommend the use of the term xanthate, although it is in current use in the scientific literature: 〕 The name ''xanthates'' is derived from Greek ξανθός (:ksantʰós), meaning “yellowish, golden”, and indeed most xanthate salts are yellow. They were discovered and named in 1823 by the Danish chemist William Christopher Zeise. These organosulfur compounds are important in two areas, the production of cellophane and related polymers from cellulose and secondly in mining for the extraction of certain ores.〔Kathrin-Maria Roy "Xanthates" in ''Ullmann's Encyclopedia of Industrial Chemistry'', 2005, Wiley-VCH, Weinheim. 〕 They are also versatile intermediates in organic synthesis. Xanthates also refer to esters of xanthic acid. These esters have the structure ROC(=S)SR'.
==Formation and structure==
Xanthate salts are produced by the reaction of an alcohol with sodium or potassium hydroxide and carbon disulfide:〔〔This report gives a detailed procedure for the potassium ethyl xanthate: 〕
:ROH + CS2 + KOH → ROCS2K + H2O
The reaction involves the attack of the alkoxide salt. For example, sodium ethoxide gives sodium ethyl xanthate. Virtually any alcohol can be used in this reaction. Technical grade xanthate salts are usually of 90–95% purity. Impurities include alkali-metal sulfide, sulfate, trithiocarbonates, thiosulfate, sulfite, or carbonate as well as residual raw material such as alcohol and alkali hydroxide. These salts are available commercially as powder, granules, flakes, sticks, and solutions are available. China is a major exporter of granules.
Some commercially important xanthate salts include:
*sodium ethyl xanthate CH3CH2OCS2Na,
*potassium ethyl xanthate, CH3CH2OCS2K,
*sodium isopropyl xanthate
*sodium isobutyl xanthate
*potassium amyl xanthate
The OCS2 core of xanthate salts and esters is characteristically planar. The central carbon is sp2-hybridized.
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