Triethylsilane with ozone

If the reaction is four-centered (5 - 7), a silicon hydroperoxide should be formed. The reaction of triethylsilane with ozone was monitored by NMR at —57°C. The only species observed under these conditions were the silane and the silanol no evidence for a hydroperoxide intermediate which might have been stable at that temperature (35) was detected, and chemical tests for peroxides proved negative (5, 6). As the concentration of ozone was increased from zero to saturation, the spectrum of the silane completely disappeared with the concurrent appearance of the silanol NMR spectrum. 

Alkene Oxidation Reactions. The reaction of triethylsilane with ozone and use of the intermediate triethylsilyl hydrotrioxide in oxidation reactions have been described. Initial oxidation reactions reported included the formation of the 9,10-endoperoxide from 9,10-dimethylanthracene (eq 1), and an allyUc hydroperoxide from 2,3-dimethyl-2-butene (eq 2). Researchers also observed a near-IR emission from triethylsilyl hydrotrioxide as it decomposed at —60°C, consistent with generation of singlet oxygen. Other workers have characterized triethylsilyl hydrotrioxide by NMR spectroscopy and and measured the kinetics of its decomposition in deuterated acetone. ... 

Formation of Singlet Oxygen. Triethylsilane reacts with ozone at —78 °C in inert solvents to form triethylsilyl hydro trioxide, which decomposes at slightly elevated temperatures to produce triethylsilanol and Singlet Oxygen. This is a convenient way to generate this species for use in organic synthesis. ... 

Formation of Singlet Oxygen. Triethylsilane reacts with ozone at —78 °C in inert solvents to form triethylsilyl... 

Corey and coworkers have shown that trimethylsilyl hydrotrioxide, produced by the low-temperature (—78°C) ozonization of triethylsilane, decomposes at higher temperatures to give singlet oxygen. The formation of singlet oxygen was confirmed by the change in the IR emission at 1278 nm with time ( O2 2). ... 

A second possibility is that the ozone forms some kind of complex with the silane before attack on the hydrogen. From this complex, all hydrogens are equally accessible, and the decomposition is first order in complex. In the hope of observing such a complexation, the ultraviolet spectra of ozone/silane mixtures in carbon tetrachloride were examined (33). Although no spectral bands attributable to a silicon-ozone complex were found, it was observed that any silicon-containing species catalyzed the decomposition of ozone. That is, not only triethylsilane, but tri-ethylsilanol and tetramethylsilane as well, destroy ozone in carbon tetrachloride. This result indicates an association of the ozone with the silicon atom, regardless of the functionality of the silicon species (within the types examined) and completely independent of the silicon substrate s... 

Preparative Methods addition of triethylsilane (2 equiv) to a cold (—78 °C), saturated methylene chloride solution of ozone (ca. 0.04 M) results in discharge of the color with formation of triethylsilyl hydrotrioxide within 45 s. ... 

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