Read the passage given and answer the question.

Phenol and alcohol have the same functional group (-OH) but phenols are stronger acids than alcohols due to the resonance stabilization of phenoxide ion than alkoxide ion \((-RO^-)\). Electron withdrawing groups tend to increase the acidic strength while electron releasing groups tend to decrease it.

Identify the product of the given reaction:

Salicylaldehyde

The correct answer is option 4. Salicylaldehyde.

The given reaction is Reimer-Tiemann Reaction.

Reimer Tiemann reaction is a type of substitution reaction named after chemists Karl Reimer and Ferdinand Tiemann. The reaction is used for the ortho-formylation of \(C_6H_5OH\) (phenols). When phenol, i.e. \(C_6H_5OH\), is treated with \(CHCl_3\) (chloroform) in the presence of \(NaOH\) (sodium hydroxide), an aldehyde group \((-CHO)\) is introduced at the ortho position of the benzene ring leading to the formation of o-hydroxybenzaldehyde. The reaction is popularly known as the Reimer Tiemann reaction.

Mechanism:

Step I: First, a strongly basic hydroxide solution is used to deprotonate the chloroform. Deprotonation is the elimination of the hydrogen atom. The chloroform carbanion is formed by removing the hydrogen atom. The chloroform carbanion will swiftly undergo alpha elimination, yielding dichlorocarbene \((CCl_2)\), the reaction’s major reactive species.

Step II: Base extracts the hydrogen atom from the \(-OH\) group to generate the phenoxide ion. The phenoxide’s negative charge is delocalized into the aromatic ring, making it more nucleophilic.

Step III: The addition of dichlorocarbene results in the formation of an intermediate i.e., dichloromethyl-substituted phenol. The resulting intermediate is then exposed to basic hydrolysis to yield ortho-hydroxybenzaldehyde.