Азидотриметилсилан

Химические свойства

clear colorless to slightly yellow liquid

Физические свойства

bp 95–96°C; n20 D 1.416; d 0.868 g cm?3; fp23°C; IR νmax 2100 cm?1; 1H NMR (CDCl3) δ = 0.22.

Использование

Many applications of TMSA in organic synthesis have been reported but only representative examples are described herein. Substitution Reactions. Benzyl,allyl,and substituted alkyl halides are converted to the corresponding azides in 60–100% yields via reactions with TMSA under neutral conditions in a nonaqueous solvent (eq 1).By using tin(IV) chloride as a catalyst, secondary and tertiary cyclic and polycyclic halides are similarly transformed into the corresponding azides in 50–92% yields (eq 1).

Подготовка

several methods for the synthesis of this azide have been reported.The procedure involving aluminum chloride is not recommended, since an explosive product is formed.Azidotrimethylsilane is now commercially available, and a representative synthetic procedure is as follows. A mixture of sodium azide and chlorotrimethylsilane is refluxed in di-n-butyl ether for 2 days and the azide is safely distilled directly from the reaction vessel. Purer compound (99% content) is obtained by redistillation of the product. Several improved conditions have been reported for the preparation of this azide.In these procedures, trimethylsilyl chloride is reacted with sodium azide either neat or in a high boiling point solvent, such as a mixture of silicone oil and polyethylene glycol. Distillation of the crude product usually provides trimethylsilyl azide (TMSA) in high purity (97.9%) and yield (97%).

Методы очистки

Distil the azide through a Vigreux column (p 11) in a N2 atmosphere maintaining the oil bath temperature thermostat at 135-140o . Check the purity by 1H NMR [CHCl3, : single peak at 13cps from Me4Si]. Likely impurities are siloxane hydrolysis products. The azide is thermally stable even at 200o when it decomposes slowly without explosive violence. All the same, it is advisable to carry out the distillation behind a thick safety screen in a fumehood because unforseen EXPLOSIVE azides may be formed on long standing. [Birkofer & Wagner Org Synth Coll Vol VI 1030 1988.]