Hydride generation activity of arsenosugars and thioarsenicals |
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Authors: | Rajendra Regmi Bruce F Milne Jörg Feldmann |
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Institution: | (1) Department of Chemistry, College of Physical Sciences, University of Aberdeen, Old Aberdeen, AB24 3UE, UK;(2) Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha 164, 4050-047 Porto, Portugal |
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Abstract: | The major arsenosugar compounds have been reported to be hydride-generation-active, however to a lesser extent in comparison
with the inorganic arsenicals. We report here for the first time the identity and quantity of the volatile arsenicals generated
by As-sugar-SO3, As-sugar-SO4, dimethylarsinoyl acetic acid and dimethylarsinoyl ethanol. Only one major volatile compound was identified for all four
compounds studied: dimethylarsine. This means that the As–C bond to the longer carbon chain was cleaved during the hydride-generation
process. Theoretical calculations at the RHF/6-31G(d,p) ab initio level confirm that this As–C bond is much weaker than the
As–CH3 bonds. Furthermore, it was revealed that the sulphur analogue of dimethylarsinic acid (DMAS ) is hydride-generation-active
at pH 7 in contrast to dimethylarsinic acid, despite the fact that arsenic is also pentavalent. This has been substantiated
by the calculation of the change in susceptibility of the arsenic towards nucleophilic attack when oxygen is replaced by sulphur.
Hence, DMAS can easily be mistaken for a trivalent arsenic species. |
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Keywords: | Arsenic Hydride generation Arsenosugars Thioarsenicals Inductively coupled plasma mass spectrometry Cryotrapping Fukui |
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