The number of hydroxyl groups present in the product $$P$$ is __________.

The starting compound contains both a phenolic $$-OH$$ group and an aldehyde $$-CHO$$ group.

$$PhMgBr$$ is not only a strong nucleophile but also a very strong base. In the presence of an acidic proton, acid-base reaction occurs preferentially over nucleophilic addition.

The phenolic proton is acidic and reacts immediately with $$PhMgBr$$. As a result, the Grignard reagent is consumed in deprotonating the phenol to form a phenoxide salt and benzene.

Since only one equivalent of $$PhMgBr$$ is present, the entire reagent is consumed in this acid-base reaction. No Grignard reagent remains available to attack the aldehyde group.

During the subsequent treatment with aqueous $$NH_4Cl$$, the phenoxide ion is protonated back to the original phenol.

Therefore, the aldehyde group remains unchanged throughout the reaction sequence, and the final product is identical to the starting material.

The product contains one phenolic hydroxyl group.

Hence, the number of hydroxyl groups present in product $$P$$ is

$$1$$