which of the following reactions of alkanols does not involve c-O bond breadking ?

Options

A. `CH_(3) CH_(2) OH +SOCl_(2)`
B. `CH_(3)CH(OH)CH_(3)+PBr_(3)`
C. `CH_(3)CH_(2)OH+CH_(3)COOH`
D. ROH +HX

Answer

To determine which reaction of alkanols does not involve the breaking of the carbon-oxygen (C-O) bond, we will analyze each reaction step by step.

### Step 1: Analyze the First Reaction
The first reaction involves CH3CH2OH (ethanol) reacting with SOCl2 (thionyl chloride).

- In this reaction, the lone pair of electrons on the oxygen of the alcohol attacks the electrophilic sulfur atom in SOCl2.
- This leads to the formation of an intermediate where the C-O bond is broken as the hydroxyl group (OH) is replaced by a chlorine atom (Cl).
- Therefore, this reaction **involves C-O bond breaking**.

**Hint:** Look for the replacement of the hydroxyl group in reactions involving thionyl chloride.

### Step 2: Analyze the Second Reaction
The second reaction involves CH3CH(OH)CH3 (isopropanol) reacting with PBr3 (phosphorus tribromide).

- Here, the hydroxyl group (OH) is replaced by a bromine atom (Br).
- This also results in the breaking of the C-O bond as the OH group is substituted.
- Thus, this reaction **also involves C-O bond breaking**.

**Hint:** Substitution reactions typically involve breaking the C-O bond when replacing the hydroxyl group.

### Step 3: Analyze the Third Reaction (Esterification)
The third reaction is an esterification reaction where a carboxylic acid (CH3C(=O)OH) reacts with an alcohol (CH3CH2OH) in the presence of concentrated H2SO4.

- In this reaction, the concentrated H2SO4 acts as a dehydrating agent.
- The bond between the oxygen and hydrogen (O-H) of the alcohol is broken to form water, but the C-O bond remains intact.
- Therefore, this reaction **does not involve C-O bond breaking**.

**Hint:** Look for reactions that form water as a byproduct; they may not involve C-O bond breaking.

### Step 4: Analyze the Fourth Reaction
The fourth reaction involves an alcohol reacting with an acid (HX).

- In this case, the alcohol donates its lone pair to the proton (H+) from the acid, forming an oxonium ion (R-OH2+).
- To stabilize the positive charge, the C-O bond is broken, leading to the formation of a carbocation and the release of water.
- Hence, this reaction **involves C-O bond breaking**.

**Hint:** Protonation of alcohols typically leads to C-O bond cleavage.

### Conclusion
After analyzing all four reactions, we find that the only reaction that does not involve the breaking of the C-O bond is the **third reaction (esterification)**.

### Final Answer
The reaction of esterification does not involve C-O bond breaking.