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Hexamethyldisilazane is used as a solvent in organic synthesis and organometallic chemistry. It is often used as an adhesion promoter for photoresist in photolithography. Further, it is used for the preparation of trimethylsilyl ethers from hydroxy compounds. It is used as an alternative to critical point drying during sample preparation in electron microscopy. It is added to analyte to get silylated diagnostic products during pyrolysis in gas chromatography- mass spectrometry.
Convenient, mild silylating reagent which generates gaseous ammonia as the only by-product (see Appendix 4). Non-acidic substrates normally require a catalyst.
Silylation of alcohols, including carbohydrates, is catalyzed by TMS chloride: J. Org. Chem., 23, 50 (1958); J. Am. Chem. Soc., 85, 2497 (1963); Chem. Ind. (London), 794 (1984). Silylation of phenols occurs readily, see also: Liebigs Ann. Chem., 20 (1973).
HMDS in the presence of TMS chloride permits the selective O-silylation of amino alcohols: Synthesis, 990 (1988). Alcohols and phenols can be silylated in the presence of amines and thiols with ZnCl2 as catalyst: Synth. Commun., 23, 1633 (1993).
For conversion of carbonyl groups to silyl enol ethers, see Iodotrimethylsilane, A12902.
A range of catalysts for silylation with HMDS, including saccharin and sodium saccharin, has been recommended: J. Org. Chem., 47, 3966 (1982), for silylation of alcohols, phenols, thiols, carboxylic acids, amides, thioamides, hydroxamic acids, hydrazides, NH-groups of heterocycles, hydrazines, 1,3-diketones, etc. The use of TBAF (0.02 eq.) or iodine (0.01 eq.) also provide mild procedures for O-silylation: Tetrahedron Lett., 35, 8409 (1994); J. Org. Chem., 65, 7228 (2000).
Can also function as a protected form of ammonia, e.g. to convert acid chlorides to primary amides: Synthesis, 517 (1985), and substituted maleic anhydrides to maleimides: Tetrahedron Lett., 31, 5201 (1990).
In combination with DMSO, thiols are oxidized to disulfides under nearly neutral conditions: Synlett, 346 (2002).
Demin, V. N.; Smirnova, T. P.; Borisov, V. O.; Grachev, G. N.; Smirnov, A. L.; Khomyakov, M. N. Physical-chemical properties of silicon carbonitride films prepared using laser-plasma deposition from hexamethyldisilazane. Glass Phys. Chem. 2015, 41 (2), 232-236.
Molnár, B.; Csámpai, A.; Molnár-Perl, I. Hexamethyldisilazane as an Acylation Generator for Perfluorocarboxylic Acids in Quantitative Derivatization of Primary Phenylalkyl Amines Confirmed by GC/MS and Computations. Anal. Chem. 2014, 87 (2), 848-852.
Mentions de danger (UE): H225-H302-H311-H331-H314-H318
Highly flammable liquid and vapour. Harmful if swallowed. Toxic in contact with skin. Toxic if inhaled. Causes severe skin burns and eye damage. Causes serious eye damage.
Mentions de prudence: P210-P260u-P303+P361+P353-P305+P351+P338-P405-P501a
Keep away from heat/sparks/open flames/hot surfaces. - No smoking. Do not breathe dusts or mists. IF ON SKIN (or hair): Remove/Take off immediately all contaminated clothing. Rinse skin with water/shower. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. Store locked up. Dispose of contents/container in accordance with local/regional/national/international regulations.