Step 1: Reagent character. Alcoholic KOH functions as a strong base, favoring E2 elimination over substitution. Step 2: Elimination in 3-bromo-2-cyclohexene. Removal of HBr introduces an additional double bond, extending conjugation within the ring. Step 3: Driving force for aromatization. The system undergoes further dehydrogenation to achieve full cyclic conjugation, forming the aromatic benzene ring and gaining substantial resonance stabilization. Step 4: Stability preference. Aromatic stabilization renders benzene the thermodynamically favored major product. Step 5: Conclusion. The reaction proceeds via aromatization to yield benzene as the principal product.
