Consider the following reaction `CH_3-underset((A))(CH_2)-O-H+CH_3-underset((B))overset(O)overset(||)C-OHrarrCH_3-overset(O)overset(||)C-O-CH_2-CH_3+HOH` In the above reaction ester formation takes place by

Options

A. Breaking of O - H bond of A and O - H bond of B
B. Breaking of C - O bond of A and C - O bond of B
C. Breaking of O - H bond of A and C - O bond of B
D. Breaking of C - O bond of A and O - H bond of B

Answer

To solve the problem of ester formation in the given reaction, we will analyze the reactants and the mechanism of the reaction step by step.

### Step 1: Identify the Reactants
The reactants in the reaction are:
1. An alcohol: \( CH_3-CH_2-OH \) (which we can denote as compound A)
2. A carboxylic acid: \( CH_3-C(=O)-OH \) (which we can denote as compound B)

### Step 2: Understand the Reaction Mechanism
Ester formation occurs through a condensation reaction between an alcohol and a carboxylic acid, resulting in the formation of an ester and water. The general reaction can be represented as:
\[ \text{Alcohol} + \text{Carboxylic Acid} \rightarrow \text{Ester} + \text{Water} \]

### Step 3: Protonation of the Carboxylic Acid
In the presence of an acid catalyst (H+), the hydroxyl group (OH) of the carboxylic acid becomes protonated, increasing the electrophilicity of the carbonyl carbon. This makes it more susceptible to nucleophilic attack by the alcohol.

### Step 4: Nucleophilic Attack
The nucleophile in this reaction is the alcohol (A). The lone pair of electrons on the oxygen of the alcohol attacks the electrophilic carbon of the protonated carboxylic acid. This forms a tetrahedral intermediate.

### Step 5: Formation of the Ester
In the tetrahedral intermediate, two hydroxyl groups are present on the same carbon, which is unstable. Therefore, one of the hydroxyl groups (from the carboxylic acid) will leave as water (H2O), leading to the formation of the ester.

The final product can be represented as:
\[ CH_3-C(=O)-O-CH_2-CH_3 \]
This is the ester formed from the reaction.

### Step 6: Identify the Bonds Broken
In this reaction:
- The bond between the hydroxyl group (OH) of the alcohol (A) is broken.
- The bond between the carbonyl carbon (C=O) of the carboxylic acid (B) is also broken.

### Conclusion
The reaction leads to the formation of an ester and water, confirming that ester formation takes place via the condensation reaction between the alcohol and the carboxylic acid.