Bis(trimethylsilyl)amine
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Names | |||
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Preferred IUPAC name
1,1,1-Trimethyl-N-(trimethylsilyl)silanamine[1] | |||
Other names
Bis(trimethylsilyl)azane
Bis(trimethylsilyl)amine 1,1,1,3,3,3-Hexamethyldisilazane Hexamethyldisilazane | |||
Identifiers | |||
3D model (
JSmol ) |
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Abbreviations | HMDS | ||
635752 | |||
ChEBI | |||
ChemSpider | |||
ECHA InfoCard
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100.012.425 | ||
EC Number |
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MeSH | Hexamethylsilazane | ||
PubChem CID
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RTECS number
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UNII | |||
UN number | 2924, 3286 | ||
CompTox Dashboard (EPA)
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Properties | |||
C6H19NSi2 | |||
Molar mass | 161.395 g·mol−1 | ||
Appearance | Colorless liquid | ||
Density | 0.77 g cm−3 | ||
Melting point | −78 °C (−108 °F; 195 K) | ||
Boiling point | 126 °C (259 °F; 399 K) | ||
Slow hydrolysis | |||
Refractive index (nD)
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1.4090 | ||
Hazards | |||
NFPA 704 (fire diamond) | |||
Safety data sheet (SDS) | External MSDS | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Bis(trimethylsilyl)amine (also known as hexamethyldisilazane and HMDS) is an
Synthesis and derivatives
Bis(trimethylsilyl)amine is synthesized by treatment of trimethylsilyl chloride with ammonia:[3]
- 2 (CH3)3SiCl + 3 NH3 → [(CH3)3Si]2NH + 2 NH4Cl
Ammonium nitrate together with triethylamine can be used instead.[4] This method is also useful for 15N isotopic enrichment of HMDS.
Alkali metal bis(trimethylsilyl)amides result from the deprotonation of bis(trimethylsilyl)amine. For example, lithium bis(trimethylsilyl)amide (LiHMDS) is prepared using n-butyllithium:
- [(CH3)3Si]2NH + BuLi → [(CH3)3Si]2NLi + BuH
LiHMDS and other similar derivatives: sodium bis(trimethylsilyl)amide (NaHMDS) and potassium bis(trimethylsilyl)amide (KHMDS) are used as a non-nucleophilic bases in synthetic organic chemistry.
Use as reagent
Hexamethyldisilazane is employed as a reagent in many organic reactions:
1) HMDS is used as a reagent in condensation reactions of heterocyclic compounds such as in the microwave synthesis of a derivative of xanthine:[5]
2) The HMDS mediated trimethylsilylation of alcohols, thiols, amines and amino acids as protective groups or for intermediary organosilicon compounds is found to be very efficient and replaced TMSCl reagent.[6]
Silylation of glutamic acid with excess hexamethyldisilazane and catalytic TMSCl in either refluxing xylene or acetonitrile followed by dilution with alcohol (methanol or ethanol) yields the derived lactam pyroglutamic acid in good yield.
HMDS in the presence of catalytic iodine facilitates the silylation of alcohols in excellent yields.
3) HMDS can be used to silylate laboratory glassware and make it hydrophobic, or automobile glass, just as Rain-X does.
4) In gas chromatography, HMDS can be used to silylate OH groups of organic compounds to increase volatility, this way enabling GC-analysis of chemicals that are otherwise non-volatile.
Other uses
In
In
In pyrolysis-gas chromatography-mass spectrometry, HMDS is added to the analyte to create silylated diagnostic products during pyrolysis, in order to enhance detectability of compounds with polar functional groups.[10]
In plasma-enhanced chemical vapor deposition (PECVD), HMDS is used as a molecular precursor as a replacement to highly flammable and corrosive gasses like SiH4, CH4, NH3 as it can be easily handled. HMDS is used in conjunction with a plasma of various gases such as argon, helium and nitrogen to deposit SiCN thin films/coatings with excellent mechanical, optical and electronic properties.[11]
See also
References
- ISBN 978-0-85404-182-4.
- ISBN 9780080465180.
- ISBN 978-0-470-13236-4.
- ^ S.V. Chernyak; Yu. G. Yatluk; A.L. Suvorov (2000). "A Simple Synthesis of Hexamethyldisilazane (Translated from Zhurnal obshcheĭ khimiĭ, Vol. 70. No. 8, 2000. p1401)". Russian Journal of General Chemistry. 70: 1313.
- PMID 17067400.
- ISBN 0471936235.
- ^ Cornell NanoScale Science & Technology Facility. "CNF - Photolithography Resist Processes and Capabilities". Archived from the original on 2019-09-07. Retrieved 2008-01-29.
- ^ "YES Prime Oven | Stanford Nanofabrication Facility". snfexfab.stanford.edu. Stanford Nanofabrication Facility.
- S2CID 26050695.
- PMID 11486868.
- .