Xanthic acid, esters

Carbon disulfide is the dithio derivative of C02. It is only a weak electrophile. Actually, it is so unreactive that in many reactions it can be used as a solvent. Consequently, only good nucleophiles can add to the C—S double bond of carbon disulfide. For example, alkali metal alkoxides add to carbon disulfide forming alkali metal xan-thates A (Figure 7.4). If one were to protonate this compound this would provide compound B, which is a derivative of free dithiocarbonic acid. It is unstable in the condensed phase in pure form, just as free carbonic acid and the unsubstituted carbamic acid (Formula B in Figure 7.3) are unstable. Compound B would therefore decompose spontaneously into ROH and CS2. Stable derivatives of alkali metal xanthates A are their esters C. They are referred to as xanthic add esters or xanthates. They are obtained by an alkylation (almost always by a methylation) of the alkali metal xanthates A. You have already learned about synthesis applications of xanthic acid esters in Figures 1.32, 4.13, and 4.14. 

Esters derived from the primary alcohols are the most stable and those derived from the tertiary alcohols are the least stable. The decomposition temperature is lower in polar solvents, eg, dimethyl sulfoxide (DMSO), with decomposition occurring at 20°C for esters derived from the tertiary alcohols (38). Esters of benzyl xanthic acid yield stilbenes on heating, and those from neopentyl alcohols thermally rearrange to the corresponding dithiol esters (39,40). The dialkyl xanthate esters catalytically rearrange to the dithiol esters with conventional Lewis acids or trifluoroacetic acid (41,42). The esters are also catalytically rearranged to the dithiolesters by pyridine Ai-oxide catalysts (43) ... 

Esters of dithioacids often give 1,2,3,4-thiatriazoles in good yield on treatment with sodium azide [Eq. (2)] however, this method is not as general as method 1. Dithiocarbamic and xanthic acids and... 

Salts of O-alkyldithiocarbonatcs ( xanthates ) are hazardous as dusts, forming explosive suspensions in air. The lower-alkyl salts are claimed to be explosive in the solid state when dry [1]. Explosions reported when drying hydrated xanthate salts are probably the consequence of release of carbon disulphide to form an inflammable atmosphere of very low autoignition temperature in the oven [2], Xanthate esters are thermally unstable by a variety of eliminations and rearrangements, all distinctly exothermic and many evolving extremely flammable gases and vapours. Free xanthic acids, which may be isolated on acidification, decompose autocatalytically and perhaps explosively [3],... 

Uses and Physiological Properties of Carbon Disulphide.—Besides its employment as a solvent (see p. 260), carbon disulphide is used extensively in the manufacture of viscose silk. Viscose is a solution of the sodium salt of the cellulose ester of thiolthioncarbonic acid (p. 268) in water or dilute aqueous sodium hydroxide, or it may be described as an aqueous solution of the sodium salt of cellulose xanthic acid. For its production cellulose is steeped in concentrated sodium hydroxide solution and then pressed, the product being called alkali-cellulose and the formula CeH10O5.NaOH assigned to it. This is converted into viscose by treatment with carbon disulphide, when the colour changes to golden yellow ... 

Xanthic acid is obtained as a colourless oil by the action of dilute sulphuric acid on the potassium salt in the cold. It decomposes at 24° C. into ethyl alcohol and carbon disulphide. The ethyl ester, when heated with water, yields carbon dioxide, hydrogen sulphide, ethyl alcohol and ethyl mercaptan, whilst with ammonia, ethyl mereaptan and ccanthogenamide or thiourethaiie, CgH5O.CS.NHa, are produced. These reactions indicate that the constitution of the acid is... 

Synonyms Amyl potassium xanthate Carbonic acid, dithio-, 0-pentyl ester, potassium salt Carbonodithioic acid, 0-pentyl ester, potassium salt Dithiocarbonic acid, 0-pentyl ester, potassium salt KAX PAX Pentyl xanthic acid, potassium salt Potassium amyixanthogenate Potassium n-amylxanthogenate Potassium pentyl xanthate Potassium pentyl xanthogenate Xanthic acid, pentyl-, potassium salt Empirical CeHiiKOS2 Formula C4H9CH20C(S)S"K"... 

Synonyms Butyl potassium xanthate Butyl xanthic acid, potassium salt Carbondithioic acid, O-butyl ester, potassium salt Dithiocarbonic acid-o-butyl ester potassium salt Potassium o-butyl carbonodithioate Potassium butyl xanthate Potassium-o-butyl xanthate Potassium butyl xanthogenate Potassium xanthogenate butyl ether Classification Potassium salt of dithiocarbonic acid ester... 

Synonyms Butyl xanthic acid sodium salt Carbonodithioic acid, 0-butyl ester, sodium salt Dithiocarbonic acid, 0-butyl ester, sodium salt Sodium 0-butyl carbonodithioate Sodium o-butyl dithiocarbonate Sodium butyl xanthogenate Empiricai C5HgNaOS2... 

Synonyms Carbonodithioic acid, 0-(2-methylpropyl) ester, sodium salt Dithiocarbonic acid, 0-isobutyl ester, sodium salt Isobutyl xanthic acid, sodium salt SIBX Classification Sodium salt of a dithiocarbonic acid ester... 

As has been indicated in a number of studies, sulfur-containing compounds give a synergic effect with amines and phenols in the stabilization of high-molecular compounds [89, 279]. The following have been proposed and are used as stabilizers of polyvinyl chloride mercaptides of antimony [280, 281], condensation products of aldehydes or ketones with mercaptans [63], thioesters [282], salts of thioacids [283], aromatic esters of aliphatic sulfonic acids [284], esters of xanthic acids [285] the use of the polysulfide of the composition... 

Methyl dithiocarbamates attack the reactive methylene groups of cyano-acetamide, cyanoacetic ester, or bis(phenylsulphonyl)methane with loss of methanethiol and formation of the thioamides R R CHC(S)NR R . Diazomethane and phenyldiazomethane, which is more reactive, insert into dialkyl-aminomethyl esters of dialkyldithiocarbamic acids (152 X = NR R ) or ethyl xanthic acid (152 X = OEt), giving esters (153 R = H or Ph, X = NR R or OEt) that have an extended alkylene chain. ... 

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