Questions Most Wittig reagents must be generated in situ fro

Questions Most Wittig reagents must be generated in situ from a phosphonium salt and base. The phosphorane used in this experiment is one of the few Wit- tig reagents, known as stabilized ylides, that can be stored in a bottle. Explain what makes this particular phosphorane stable relative to, for ex- ample, Ph,P CH 1. 2. After the reaction mixture was added to the top of the silica gel column, the instructions stated: \"Open the stopcock and drain the column until the meniscus is just above the top layer of material. Add another 0.5 mL

Solution

Wittig reaction

1. The phosphorane synthesized here is more stable due to the oxygen atoms present on the phosphorous atom. This is thus a more conjugated ylide and thus more stable.

2. This step is important so that no compound is left above the layer of silica gel and gets dissolved in the solvent added later. The compound left if not washed like the procedure would increase the trailing factor for the compound on the column and we would get mixture of compounds.

3. The phosphorane used here allows for a more easy formation of carbanion (ylide) and also the phosphorous containing negatively charged leaving group is more stable due to resonace stabilization of the resultant charge on oxygen atom.

4. starting material not specified