Thiomalic acid, oxidation

There is spectroscopic and kinetic evidence for complex formation in the oxidation of thiomalic acid in perchlorate media. Under conditions of a large excess of reductant the kinetics may be interpreted in terms of the mechanism (RSH= thiol)... 

Hill, J. and McAuley, A. (1968) Metal-ion oxidations in solution. Part IV. The oxidation of thiomalic acid by cobalt(III) ions. /. Chem. Soc. A, 2405—2408. 

The oxidation of thioglycolic, thiomalic, and thiolactic acids in DMSO is first-order in tetrabutylammonium-12-tungstocobaltate(III) ion. ... 

Thiols disappear from urine in contact with air, forming both homo- and mixed-disulfides. Rapid losses have been reported for cysteine, D-penicillamine, and thiomalate. It is therefore essential to acidify urine immediately after it has been voided. Collection of urine into 10 mL of 6 mol L hydrochloric acid per litre of urine inhibits thiol oxidation for at least 12 h at room temperature. Although addition of EDTA and storing at —20 °C inhibits thiol degradation, further loss is still possible. Dithiothreitol (DTT) can be used to maintain thiols in the reduced form prior to analysis, but this procedure can give erroneous results since DTT might release thiols from mixed disulfides. Furthermore, DTT often interferes with HPLC-ED methods. 

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