Question

how to prepare witttig reagent

Answer 1

The Wittig reaction or Wittig olefination is a chemical reaction of an aldehyde or ketonewith a triphenyl phosphonium ylide (often called a Wittig reagent) to give an alkene and triphenylphosphine oxide.

aldehyde or ketone + triphenyl phosphonium ylide --- alkene + triphenylphosphine oxide

Answer 2

Answer:

Wittig reagents are usually prepared from a phosphonium salt, which is in turn prepared by the reaction of triphenylphosphine with an alkyl halide via an SN2 reaction. The alkylphosphonium salt is deprotonated with a strong base such as n-butyllithium: [Ph3P+CH2R]X− + C4H9Li → Ph3P=CHR + LiX + C4H.