Answer
🔬 Wittig Reaction Essentials
The Wittig reaction involves the conversion of a carbonyl compound (usually an aldehyde or ketone) into an alkene using a phosphorus ylide.
- Triphenylphosphine is needed to form the phosphonium salt, a precursor to the ylide.
- An alkyl halide reacts with triphenylphosphine to generate the phosphonium salt.
- An aldehyde acts as the electrophile that the ylide attacks to form the alkene product.
- An alkyl lithium (e.g., BuLi) is a strong base commonly used to deprotonate the phosphonium salt and generate the ylide.
🧪 While alkyl lithium is commonly used, it is not the only option. Other bases like
NaH or n-BuNa can serve the same role.
❌ Which One Is Not Absolutely Required?
Alkyl lithium is not strictly required — it can be replaced by other bases.
Thus, the reaction can proceed without alkyl lithium as long as an appropriate strong base is available to form the ylide.
✅ Final Answer:
An alkyl lithium