Butane thiols, oxidation

The oxidation of thiols is accelerated remarkably by traces of catalyst and this reaction forms the basis of petroleum sweetening processes. Although transition metal ions are the most effective catalysts, any additive capable of catalysing electron transfer accelerates the reaction. Nitrobenzene in dimethylformamide/potassium hydroxide [118], 2-nitro-thiophene, tetracyanoethylene, and 4-nitropyridine-N-oxide [118] are all good catalysts for the oxidation of 1-butane thiol. The alkaline hydrolysis of disulphides containing aryl, carbonyl, and alpha unsaturated groups also results in catalysis, apparently due to the setting up of a sulphinate—sulphenate redox cycle [119—121]. 

I. 1.4.1] catalyzes the reaction of 2-methyl-3-phytyl-l,4-naphthoquinone with oxidized dithiothreitol and water to produce 2,3-epoxy-2,3-dihydro-2-methyl-3-phytyl-l,4-naphthoquinone and 1,4-dithiothreitol. In the reverse reaction, vitamin K 2,3-epoxide is reduced to vitamin K and possibly to vitamin K hydroquinone by 1,4-dithioer-ythritol (which is oxidized to the disulfide). Some other dithiols and butane-4-thiol can also act as substrates. This enzyme is strongly inhibited by warfarin. 

Poly(2-ethyl-l-vinylimidazole) can be quaternized with ethyl and lauryl bromide. Under anaerobic conditions, the oxidation of thiophenol and 2-hydroxyethane thiol by lO-ethyl-3-raethylisoalloxazine in the presence of these micelle-like polymers, with greater than 29 mol % of lauryl group content, is 10 —I0 -fold faster than the corresponding reaction in a non-polymeric system. This is attributed to desolvation of the thiol anion, required for nucleophilic attack on the flavin, by formation of an ion pair. Strangely, the reaction with butane-1,4-dithiol is unaffected by the polymer. ... 

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