Consider the following reaction: Identify the major product.

Step-by-step solution

The given reactant is 4,4-dibromo-3-methyl-1H-pyrazol-5(4H)-one. When treated with a strong base like aqueous NaOH , it undergoes a ring-opening and fragmentation reaction to form an alkynoic acid. The hydroxide ion ( OH^- ) attacks the carbonyl carbon, leading to the cleavage of the amide-like N-C bond. This opens the ring to form a hydrazone intermediate with a carboxylate group: NH₂-N=C(Me)-C(Br)₂-COO^- . In the basic medium, the terminal nitrogen of the hydrazone is deprotonated to form an anion, ^-NH-N=C(Me)-C