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Environmental fate & pathways

Hydrolysis

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Description of key information

in water, DMTC undergoes rapid degradation by hydrolysis and is expected to hydrolyze within minutes. In water, the chloride ligand on DMTC readliy hydrolyzes to form tin hydroxide and generates HCl. As the concentration of HCl increases, the hydroxide reacts back to form DMTC until equilibrium is reached. Thus, this reaction gives the appearance that DMTC is hydrolytically stable; however, it is actually the alkyltin moiety, DMT, that is stable.
Therefore, the alkyltin moiety, DMT is hydrolytically stable (t1/2 >1 year at 25°C).

Key value for chemical safety assessment

Additional information

A study was performed in accordance with OECD Guideline 111 and to the GLP standard. The percentage hydrolysis of the test substance was less than 10% after incubation in buffer solutions pH 4.0, pH 7.0 and pH 9.0 and in Milli-Q water for 5 days at 50 °C.

It should be noted that the analytical method applied involves derivatisation of the test substance with STEB to the corresponding ethyl compounds (dimethyltin diethyl). As a consequence, the alkyltin moieties of DMTC were monitored in the hydrolysis tests, but not the chloride ligands (currently, there is no analytical method available that can quantify the entire organotin compound with its associated ligands).

A study from Bertelo gives some details: in water, DMTC undergoes rapid degradation by hydrolysis and is expected to hydrolyze within minutes. In water, the chloride ligand on DMTC readliy hydrolyzes to form tin hydroxide and generates HCl. As the concentration of HCl increases, the hydroxide reacts back to form DMTC until equilibrium is reached. Thus, this reaction gives the appearance that DMTC is hydrolytically stable; however, it is actually the alkyltin moiety, DMT, that is stable.

Therefore, the alkyltin moiety, DMT is hydrolytically stable (t1/2 >1 year at 25°C).