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Strong Base Chemistry for Chemical Synthesis
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customers make them better with intelligent system solutions
and high-quality products. Our portfolio includes innovative
Alkali Metal Amides that offer high purity, consistent quality
and a high degree of flexibility. BASF’s Alkali Metal Amides are
available in quantities from kilograms to commercial volumes,
to support the needs of our customers from lab-to-launch.
Alkali Metal Hexamethyldisilazane
Potassium hexamethyldisilazane (KHMDS), sodium hexamethyldisilazane
(NaHMDS), and lithium hexamethyldisilazane (LiHMDS) are strong non-nucleophilic
base reagents useful in a wide variety of chemical reactions and transformations.
Applications include alkylation, arylation, acylation, ring formation, isomerization,
rearrangements, aldol condensations, Wittig and Horner-Emmons reactions and
Chemists strive for selectivity and specificity in a reaction to increase the yield of the
desired product and minimize by-product formation. High selectivity and specificity
can lead to simpler, less expensive purification routes to the desired product. Alkali
metal hexamethyldisilazane (MHMDS) bases can help achieve these goals. They are
selective base reagents because of the following characteristics:
E non-nucleophilic, hindered amine base,
E higher base strength than alkali metal alkoxides,
E kinetic deprotonation achieved,
E hydrocarbon soluble base,
E reduction of substrate rarely occurs,
E not prone to one-electron-transfer side-reactions, and
E safer than alkali metal hydrides and lithium alkyls.
pKa of hexamethyldisilazane is 26 in THF, Fraser, R.R.; Mansour, T.S.; Savard, S. J. Org. Chem. 1985, 50, 3232.
pKa of hexamethyldisilazane is 26 in DMSO, Grimm, D.T.; Bartmess, J.E. J. Am. Chem. Soc. 1992, 114, 1227.
Deprotonation and Alkylations
The bulky nature and absence of protons on the atom adjacent to the nitrogen
give the MHMDS bases co