Photolytic Oxidative Demethylation of Aqueous Dimethylsiloxanols

Abstract

Dimethylsilanediol and other water-soluble dimethysiloxanols undergo aqueous photolytic oxidative demethylation with tropospheric ultraviolet radiation in the presence of suitable chromophores, such as nitrogen oxides, to give silicic acid and carbon dioxide. The "bio suitability" of the resulting silicic acid was demonstrated by monitoring the growth of diatoms (Nuviculu pelliculosa) in the irradiated aqueous media. Thus, a plausible route for the further degradation of such water soluble hydrolysis products of poly(dimethy1-siloxane) to naturally occurring materials was conclusively demonstrated. Furthermore, di-and monomethyl silanol species were shown not to be utilized by the diatom colony, even when present as completely water soluble components.

Volatilization and Sorption of Dimethylsilanediol in Soil

“…After DMSD volatilizes into the atmosphere, it should undergo oxidation of its methyl groups by reaction with sunlight-induced hydroxyl radicals in the air, in similar fashion to other volatile siloxanes [9,10]. If the compound is instead washed out of the air in rainfall, it may be oxidized in water by photolytic demethylation [11,12], or it can be microbially oxidized in soil [1].…”