Efficient Cleavage Of C-Si In Organosilicon Compounds And High Selective Oxidation Under Irradiation

The cleavage of C-Si bond of organosilicon compounds under irradiation was particularly investigated in this paper. Benzyltrimethylsilanes could be effectively cleavaged by irradiation to generate the corresponding benzyl radicals, which were further oxidized to form benzoic acid derivatives by using air as oxidant in the presence of40%aqueous hydrogen bromide catalyst under acetonitrile medium in high yield and complete conversion. The results appear to be positive significance to potential application in industry.Various substrates were effectively prepared to use for irradiation reaction. Para-and meta-substituted benzyltrimethylsilanes were formed by the reactions of Grignard type of (trimethylsilyl)magnesium chloride with (bromomethyl)benzenes, followed by Friedel-Crafts acylation of benzyltrimethylsilane to produce4-acetyl benzyltrimethylsilane. Similarly ortho-methoxybenzyltrimethylsilane was obtained by the reactions of (2-methoxyphenyl) methanide with trimethylchlorosilane.The reaction involving4-methoxybenzyltrimethylsilane as a template under irradiation was discussed in details to seek the suitable synthetic conditions and speculate the plausible mechanism. It was found that the benzoic acid of96.5%high yield in the complete conversion of substrate could be obtained at room temperature under the irradiation of the300UV PLS-SXE xenon lamps by using air in the presence of40%aqueous hydrogen bromide in acetonitrile. Based on the reaction, over ten substrates were selectively prepared under the mild conditions. Besides, the reactions involving toluene, ethylbenzene and p-xylene were further discussed under similar conditions. All synthesized reactants and products were characterized by1H NMR,13C NMR,19F NMR, MS, HRMS and IR analyses.