A study of methylation of inorganic tin by iodomethane in an aquatic environment with 13 C carbon isotope tracer technique

The methylation of tin(II) [Sn(II)] by iodomethane (CH 3 I) under environmental conditions has been further demonstrated by a 13 C carbon isotope tracer method. Methylation products are mainly monomethyltin, and very small amounts of dimethyltin. The reaction of Sn(II) and CH 3 I was investigated at pH 2, 4, 6, 8, 10 and salinity ( S ) 8, 15, 22, 28, 35%; it has been found the reaction was affected by pH and salinity, the tin methylation activity being highest at about pH 6 and S = 28% . The methylation reaction is first‐order for both CH 3 I and Sn(II), and the rate equation has been obtained as follows:\documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{{\rm d}\left[{{\rm CH}_3 {\rm Sn}} \right]}}{{{\rm d}t}} = \left({k' + k''\left[{{\rm CH}_3 {\rm I}} \right]} \right)\left. {\left[{{\rm SnY}_2 } \right]} \right) $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm where}} \hfill & {k' = 9.10 \times 10^{ - 7} \min ^{ - 1},} \hfill \\ {} \hfill & {k'' = 1.11 \times 10^{ - 6}\; {\rm mmol}^{ - 1}\; {\rm dm}^3\; \min ^{ - 1},} \hfill \\ {} \hfill & {{\rm Y} = {\rm tin\;counterion}} \hfill \\ \end{array} $$\end{document} .