Bis(trimethylsilyl)amine
Bis(trimethylsilyl)amine (also known as hexamethyldisilazane, or HMDS) a chemical reagent with molecular formula (CH3)3Si-NH-Si(CH3)3 which consists of ammonia substituted with two trimethylsilyl functional groups. It is a clear, colorless liquid that will hydrolize slowly upon exposure to water.
A bis(trimethylsilyl)amide (also known as hexamethyldisilazide) results from the deprotonation of the nitrogen atom of bis(trimethylsilyl)amines and are used as non-nucleophilic bases:
Examples of these bases are:
- Lithium bis(trimethylsilyl)amide (LiHMDS)
- Sodium bis(trimethylsilyl)amide (NaHMDS)
- Potassium bis(trimethylsilyl)amide (KHMDS)
Uses in organic chemistry
One of the uses of HMDS is as a reagent in condensation reactions of heterocyclic compounds such as in the microwave synthesis of a derivative of xanthine[1]:
Other uses
In photolithography, HMDS is often used in as an adhesion promoter for photoresist. Best results are obtained by applying HMDS from the gas phase on heated substrates.[2]
In electron microscopy, HMDS can be used as an alternative to critical point drying during sample preparation.[3]
See also
References
- ^ Microwave-assisted Ring Closure Reactions: Synthesis of 8-substituted Xanthine Derivatives and related Pyrimido- and Diazepinopurinediones Burbiel J, Hockemeyer J, Mueller C Beilstein Journal of Organic Chemistry, 2006 2:20 ( 27 October 2006 ) doi:10.1186/1860-5397-2-20
- ^ Cornell NanoScale Science & Technology Facility. "CNF - Photolithography Resist Processes and Capabilities". Retrieved 2008-01-29.
- ^ Bray DF, Bagu J, Koegler P (1993). "Comparison of hexamethyldisilazane (HMDS), Peldri II, and critical-point drying methods for scanning electron microscopy of biological specimens". Microsc. Res. Tech. 26 (6): 489–95. doi:10.1002/jemt.1070260603. PMID 8305726.
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