Premium
Simulate methylation reaction of arsenic(III) with methyl iodide in an aquatic system
Author(s) -
Chen Baowei,
Wang Thanh,
He Bin,
Yuan Chungang,
Gao Erle,
Jiang Guibin
Publication year - 2006
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.1140
Subject(s) - chemistry , carbonium ion , methyl iodide , methylation , arsenic , iodide , inorganic chemistry , reaction mechanism , environmental chemistry , medicinal chemistry , ion , organic chemistry , catalysis , biochemistry , gene
The methylation reaction of inorganic arsenic occurring in aquatic systems was studied by HPLC‐HG‐AFS as a method to separate and detect soluble methylarsenic species. Transformation from inorganic arsenic to methylarsenic was essential for major changes in toxicity to organisms. Monomethylarsenic [AsOCH 3 (OH) 2 ] was the only product in the methylation reaction of inorganic arsenic(III) with methyl iodide (MeI). This process can be described as an oxidative carbonium‐ion transfer, with MeI acting as a methyl donor. From a thermodynamic point of view, the activity of the carbonium ion and pH were the two major influencing factors. The pH dependence of redox potential of As(III) was the reason for the effect of pH on methylation of arsenic. The influences of salinity and concentration of the methyl donor may be explained by their effects on the activity of carbonium. Moreover, kinetics experiments demonstrated that the methylation reaction was first‐order for both As(III) and methyl iodide. First‐order reaction rates were also calculated at different pH, salinity and MeI, and were found to be in the range 0.0026–0.0123 h −1 . The methylation rate varied largely under different reaction conditions. Copyright © 2005 John Wiley & Sons, Ltd.