Bis(trimethylsilyl)amine
From Wikipedia, the free encyclopedia
| Bis(trimethylsilyl)amine[1] | |
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| IUPAC name |
1,1,1,3,3,3-Hexamethyldisilazane
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| Other names | Bis(trimethylsilyl)amine Hexamethyldisilazane Hexamethyldisilane HMDS |
| Identifiers | |
| CAS number | 999-97-3  |
| PubChem | 13838 |
| SMILES |
N([Si](C)(C)C)[Si](C)(C)C
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| InChI |
1/C6H19NSi2/c1-8(2,3)7-9(4,5)6/h7H,1-6H3
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| InChI key | FFUAGWLWBBFQJT-UHFFFAOYAF |
| ChemSpider ID | 13238 |
| Properties | |
| Molecular formula | C6H19NSi2 |
| Molar mass | 161.40 g/mol |
| Density | 0.76 g/cm3 |
| Melting point |
-78 °C |
| Boiling point |
125 °C |
| Hazards | |
| MSDS | External MSDS |
| NFPA 704 |
 3
1
1
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| (what is this?) (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Bis(trimethylsilyl)amine (also known as hexamethyldisilazane, or HMDS) is an organosilicon compound with the molecular formula [(CH3)3Si]2NH. The molecule is a derivative of ammonia with trimethylsilyl groups in place of two hydrogen atoms. This colorless liquid is a reagent and a precursor to bases that are popular in organic synthesis and organometallic chemistry.
Contents |
[edit] Preparation and reactions
It is prepared by treatment of trimethylsilyl chloride with ammonia:[2]
- 2 (CH3)3SiCl + 3 NH3 → [(CH3)3Si]2NH + 2 NH4Cl
The product is usually handled using air-free techniques since it hydrolyzes slowly in humid air.
Alkali metal bis(trimethylsilyl)amides result from the deprotonation of bis(trimethylsilyl)amine. For example lithium bis(trimethylsilyl)amide (LiHMDS) is prepared using butyl lithium:
- [(CH3)3Si]2NH + BuLi → [(CH3)3Si]2NLi + C4H10
Together with sodium bis(trimethylsilyl)amide (NaHMDS) and potassium bis(trimethylsilyl)amide (KHMDS), LiHMDS is used as non-nucleophilic bases.
[edit] Reactions
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:[3]
[edit] 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.[4]
In electron microscopy, HMDS can be used as an alternative to critical point drying during sample preparation.[5]
In pyrolysis-gas chromatography-mass spectrometry, HMDS is added to the analyte to create sylilated diagnostic products during pyrolysis, in order to enhance detectability of compounds with polar functional groups.[6]
[edit] See also
[edit] References
- ^ Merck Index, 13th Edition, 4708.
- ^ Robert C. Osthoff, Simon W. Kantor (1957). "Organosilazane Compounds". Inorg. Synth. 5: 55–64. doi:.
- ^ Burbiel JC, Hockemeyer J, Müller CE (2006). "Microwave-assisted ring closure reactions: synthesis of 8-substituted xanthine derivatives and related pyrimido- and diazepinopurinediones". Beilstein J Org Chem 2: 20. doi:. PMID 17067400. PMC 1698928. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1698928.
- ^ Cornell NanoScale Science & Technology Facility. "CNF - Photolithography Resist Processes and Capabilities". http://www.cnf.cornell.edu/cnf_process_photo_resists.html#hmds. 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:. PMID 8305726.
- ^ Giuseppe Chiavari, Daniele Fabbri, and Silvia Prati (2001). "Gas chromatographic–mass spectrometric analysis of products arising from pyrolysis of amino acids in the presence of hexamethyldisilazane". Journal of Chromatography A 922 (1-2): 235–241. doi:. PMID 11486868.
