Aromatic reactivity. Part XXXIX. Effects of ortho-substituents in protodesilylation
作者:C. Eaborn、D. R. M. Walton、D. J. Young
DOI:10.1039/j29690000015
日期:——
The compounds o-XC6H4·SiMe3 with X = Br, I, But, SO3H, CO2H, NO2, Ac, and Bz have been made by appropriate desilylations of o-bis(trimethylsilyl)benzene. The rates of cleavage of these compounds, and of those with X = H, F. Cl, and Me2N, by a mixture of aqueous sulphuric acid (3 vol.) and acetic acid (4 vol.) at 50° have been measured spectrophotometrically. Values of the rates, krel, relative to that
化合物Ô -XC 6 ħ 4 ·森3与X = Br的,I,卜吨,SO 3 H,CO 2 H,NO 2,AC,和BZ已经通过适当desilylations制成ø -双(三甲基硅烷基)苯。这些化合物以及X = H,F。Cl和Me 2 N的化合物在50°下被硫酸水溶液(3体积)和乙酸(4体积)的裂解速率为用分光光度法测量。相对于苯基三甲基硅烷的比值k rel的值如下:(X =)Bu t,8·0; n =0。F,7·3×10 –2;我3·8×10–2 ; Cl,3·4×10 –2;Br,2·5×10 –2;CO 2 H,5·2×10 –3;SO 3 H,2·6×10 –3;NO 2,6·8×10 -5 ; 我2 N,6·8×10 –5。(在最后一种情况下,反应介质中的有效取代基被认为是质子化的Me 2 HN +。)