Predict the products and propose mechanisms for the following reactions. (b)

Verified step by step guidance

1. Identify the reaction type: This is a saponification reaction, where an ester reacts with a base (OH⁻) to form a carboxylate ion and an alcohol.
2. Recognize the ester: The given ester is phenyl acetate, which has a phenyl group attached to the carbonyl carbon and a methoxy group as the ester part.
3. Initiate the nucleophilic attack: The hydroxide ion (OH⁻) attacks the carbonyl carbon of the ester, leading to the formation of a tetrahedral intermediate.
4. Collapse the tetrahedral intermediate: The intermediate collapses, expelling the methoxy group as methanol and forming a carboxylate ion.
5. Protonation step: The carboxylate ion can be protonated by water to form the carboxylic acid, but in basic conditions, it remains as the carboxylate ion.

Key Concepts

Saponification

Saponification is a chemical reaction that involves the hydrolysis of esters in the presence of a strong base, typically sodium hydroxide (NaOH) or potassium hydroxide (KOH). In this process, an ester reacts with hydroxide ions to produce an alcohol and a carboxylate salt. This reaction is commonly associated with the production of soap from fats and oils, where the ester bonds in triglycerides are broken down.

Mechanism of Nucleophilic Substitution

The mechanism of nucleophilic substitution is a fundamental concept in organic chemistry where a nucleophile attacks an electrophile, resulting in the replacement of a leaving group. In the case of saponification, the hydroxide ion acts as the nucleophile, attacking the carbonyl carbon of the ester. This leads to the formation of a tetrahedral intermediate, which subsequently collapses to release the alcohol and the carboxylate ion.

Phenyl Esters

Phenyl esters are organic compounds formed from the reaction of phenol and a carboxylic acid, where the hydroxyl group of phenol is replaced by an acyl group. They are characterized by their aromatic ring and can undergo hydrolysis reactions, such as saponification. Understanding the structure and reactivity of phenyl esters is crucial for predicting the products of their reactions, particularly in the context of nucleophilic attack by hydroxide ions.