Propose mechanisms for the following reactions.
(c)

Verified step by step guidance

1. Step 1: Identify the reaction type. This is an acid-catalyzed hydrolysis of an ester, where the ester is converted into a carboxylic acid and an alcohol.
2. Step 2: Protonation of the ester carbonyl group. The ester carbonyl oxygen interacts with the acid catalyst (H⁺), leading to protonation. This increases the electrophilicity of the carbonyl carbon, making it more susceptible to nucleophilic attack.
3. Step 3: Nucleophilic attack by water. A water molecule acts as a nucleophile and attacks the carbonyl carbon, forming a tetrahedral intermediate. This intermediate contains both the original ester group and the newly added hydroxyl group.
4. Step 4: Proton transfer and cleavage. The tetrahedral intermediate undergoes proton transfer, followed by cleavage of the C-O bond between the carbonyl carbon and the ethoxy group (CH₂CH₃). This results in the formation of ethanol (CH₃CH₂OH) and a protonated carboxylic acid intermediate.
5. Step 5: Deprotonation of the carboxylic acid. The protonated carboxylic acid loses a proton to regenerate the acid catalyst (H⁺), yielding the final products: benzoic acid (Ph-C=O-OH) and ethanol (CH₃CH₂OH).

Key Concepts

Ester Hydrolysis

Ester hydrolysis is a chemical reaction where an ester reacts with water to form an alcohol and a carboxylic acid. In the presence of an acid catalyst, the ester bond is cleaved, allowing the addition of water to regenerate the acid and alcohol. This reaction is crucial in organic chemistry for understanding the behavior of esters in various conditions.

Acid Catalysis

Acid catalysis involves the use of an acid to increase the rate of a chemical reaction. In ester hydrolysis, the acid donates a proton (H+) to the carbonyl oxygen of the ester, enhancing its electrophilicity and making it more susceptible to nucleophilic attack by water. This mechanism is essential for facilitating the reaction under mild conditions.

Nucleophilic Attack

Nucleophilic attack is a fundamental concept in organic reactions where a nucleophile, a species with a high electron density, attacks an electrophile, a positively charged or electron-deficient species. In the case of ester hydrolysis, water acts as the nucleophile that attacks the carbonyl carbon of the activated ester, leading to the formation of the alcohol and carboxylic acid products.