Potassium bis(trimethylsilyl)amide

• KHMDS
• Potassium bis (trimethylsilyl ) amide

Fixed

158-162 ° C

Decomposition with water

Risk

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Potassium hexamethyldisilazide ( KHMDS short ) is the potassium salt of hexamethyldisilazane. It is a strong, sterically hindered, non-nucleophilic base with a pKa of about 26 It is frequently used for deprotonation, similar to LDA and lithium tetramethylpiperidide ( LTMP ). Its lithium analogue lithiumhexamethyldisilazide ( LHMDS ) has similar properties.

Preparation and Properties

KHMDS is from hexamethyldisilazane ( also bis ( trimethylsilyl) amine ) was prepared by reaction with potassium hydride in THF, hydrogen is released:

KHMDS is a solid at room temperature substance which is decomposed by water, with reformation of hexamethyldisilazane and potassium hydroxide. The substance is highly flammable and is corrosive.

Use

Potassium hexamethyldisilazide is used as a reagent in organic synthesis, such as the stereoselective alkylation of amino acids in the Williams or Schöllkopf alkylation. Also in the synthesis of complexes of lanthanides, it will be used. Industrially used KHMDS as the initiator in the preparation of polyethylene oxide.