Silanols trisiloxanes

The ultimate fate of higher alkyl silanols such as those produced in trisiloxane surfactant degradation, for example CH3-Si(OH)2-CH2 CH2CH2OH, has not been described, and is an area requiring further investigation. The mechanisms described above for the degradation of the methyl siloxanes may or may not be applied to higher alkylated versions. The Si-C bond is not susceptible to hydrolysis [7], and as such the abiotic elimination processes are not likely to occur. 

The described metallo-silanols exhibit high stability concerning condensation, however, the OH groups display reasonable reactivity in context with chlorosilanes. These properties can be used to transform the ferrio-silanols 4a, 4b via reaction with trimethylchlorosilane to the ferrio-di- and -trisiloxanes 13a, 13b characterized by a hydrogen substituted a-silicon. In the case of 4b the first siloxane unit is established after one day, the second takes five days (13b). The same reaction pattern can be applied for the generation of the ruthenio-disiloxanes 13c, 13d, resulting fi-om the treatment of the ruthenio-silanols 8c, 8e with Me2Si(R )Cl. 

The cyclic trisiloxanes are composed exclusively of Q silicons as shown by the MAS and H CPMAS spectra of the 600°C sample in which shifts are observed for the Q peak position, whereas the H CPMAS and hydrated MAS spectra show that the and peak positions are unaffected by the formation or elimination of the D2 species. The H-O distances in the neighboring silanol groups of the precursor (left side Eq. 14) exceeds 5.5 A, causing them to exhibit SiO-H vibrations characteristic of isolated species [164]. 

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