Aromatic reactivity. Part LI. Nitrosodesilylation as a route to nitrodesilylation products from aryltrimethylsilanes and nitric acid in acetic anhydride

Abstract

A detailed study of the reaction between p-tolyltrimethylsilane and nitric acid in acetic anhydride has shown that the formation of the nitrodesilylation product, p-nitrotoluene, takes place predominantly, and possibly exclusively, via nitrosodesilylation. Thus, (i) when the mixture of nitric acid and acetic anhydride was heated briefly to 100° then used at 15°, the ratio of nitrodesilylation to nitration product (2-nitro-4-trimethylsilyltoluene) was 90, (ii) when the mixture was made up and used at 15° the ratio was 0·64, (iii) when the mixture was made up and used at 15° but with urea present, the ratio was 0·14, and (iv) when the mixture was made up at 15° and nitrous fumes were dissolved in it before use at 15° the ratio was 4·8. With a solution of nitrous fumes in acetic acid–acetic anhydride, only the nitrodesilylation product was formed. The p-nitrotoluene formed in the reaction with solutions of acetyl nitrate or dinitrogen pentoxide also seems to be produced predominantly and exclusively through nitrosodesilylation.