трет-Бутилхлордифенилсилан

Химические свойства

Tert-Butylchlorodiphenylsilane is a colorless to pale brown oily liquid with pungent odor, may be used as silylating agent for derivatization of alcohols, ketones, carboxylic acids, amines, amides and mercaptanes selectively into functional groups in different sterical environments.

Физические свойства

colorless liquid, bp 93–95°C/0.015 mmHg; n20 D 1.5680; d 1.057 g cm?3.

Использование

Several newmethods have been developed for using the reagent to protect primary and secondary alcohols as their TBDPS ethers. In the presence of ammonium nitrate or ammonium perchlorate, reaction between TBDPS-Cl and a primary alcohol, such as benzyl alcohol, in DMF provided excellent yields of the corresponding silyl ethers in just 15 min (eq 1).19 When silver nitrate was used as promoter, the reactions gave inferior yields under otherwise identical conditions.
When TBDPS-Cl is used to react with hemiacetals, it converts hemiacetals into ring-opened silyl ether carbonyl compounds, instead of mixed acetals.Presumably, the sizable TBDPS group presents too much steric hindrance for the formation of the corresponding mixed silyl acetals.

Подготовка

a dry 1 L, three-necked round bottomed flask is equipped with a magnetic stirring bar, a 500mL equalizing dropping funnel fitted with a rubber septum, a reflux condenser, and nitrogen inlet tube. The flask is flushed with nitrogen, then charged with 127 g (0.5 mol) of diphenyldichlorosilane in 300mL of redistilled pentane. A solution of tbutyllithium in pentane (500 mL, 0.55 mol), is transferred under nitrogen pressure to the dropping funnel using a stainless steel, double-tip transfer needle. This solution is slowly added to the contents of the flask and when the addition is complete, the mixture is refluxed 30 h under nitrogen with stirring. The suspension is allowed to cool to rt, the precipitated lithium chloride is rapidly filtered through a pad of Celite, and the latter is washed with 200mL of pentane. The solvent is removed by evaporation, and the colorless residue is distilled through a short (10 cm), Vigreux column, to give 125–132 g of the colorless title compound.

Методы очистки

Purify it by repeated fractional distillaton. It is soluble in DMF and pentane [Hanessian & Lavalee Can J Chem 53 2975 1975, Robl et al. J Med Chem 34 2804 1991]. [Beilstein 4 IV 4076 for tert-butylchlorodimethylsilane.]