Identify the major product [ X ] formed in the following reaction sequence:

Step-by-step solution

The given reaction sequence is a standard Wittig reaction. Isopropyl chloride reacts with triphenylphosphine ( Ph ₃ P ) via an S _ N 2 mechanism to form an alkyltriphenylphosphonium salt. CH ₃ -CH(Cl)-CH ₃ + Ph ₃ P [ Ph ₃ P ⁺ -CH(CH ₃)₂] Cl ⁻ The phosphonium salt is treated with a strong base, butyl lithium ( BuLi ). The base abstracts the acidic -proton to generate a phosphorus ylide (Wittig reagent). [ Ph ₃ P ⁺ -CH(CH ₃)₂] Cl ⁻ + BuLi Ph ₃ P=C(CH ₃)₂ + C ₄ H ₁₀ + LiCl The ylide Ph ₃ P=C(CH ₃)₂ undergoes a nucleop