Final product formed on reaction of glycerol by HI acid is :

Options

A. Propane
B. Propanoic acid
C. iso-propyl iodide
D. Propyne

Answer

To determine the final product formed when glycerol reacts with hydrogen iodide (HI), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure of Glycerol**:
Glycerol (C3H8O3) has the following structure:
\[ \text{CH}_2\text{OH} - \text{CHOH} - \text{CH}_2\text{OH} \]
It contains three hydroxyl (–OH) groups.

2. **Reaction with Hydrogen Iodide (HI)**:
When glycerol reacts with HI, each hydroxyl group can react with HI, leading to the substitution of the –OH group with iodine (I).

3. **Mechanism of Reaction**:
- The electronegative iodine pulls electrons from the hydrogen, creating a positive charge on hydrogen.
- The hydroxyl group (–OH) is protonated to form water (H2O), which is a good leaving group.
- The iodide ion (I⁻) then attacks the carbon atom where the –OH group was, leading to the formation of iodo derivatives.

4. **Formation of Iodine Substituted Glycerol**:
After the reaction of glycerol with three moles of HI, we would initially get:
\[ \text{CH}_2\text{I} - \text{CHOH} - \text{CH}_2\text{I} \]
However, this intermediate is unstable due to steric hindrance from the bulky iodine atoms.

5. **Elimination of Iodine**:
The instability leads to the elimination of two iodine molecules (I2) from the structure, resulting in the formation of a double bond:
\[ \text{CH}_2\text{I} - \text{C} = \text{CH} - \text{CH}_2\text{I} \]

6. **Final Product Formation**:
The reaction continues with the addition of HI, leading to the formation of isopropyl iodide (C3H7I):
\[ \text{CH}_3 - \text{CH(I)} - \text{CH}_3 \]
This compound is known as isopropyl iodide.

### Final Answer:
The final product formed on the reaction of glycerol with hydrogen iodide is **isopropyl iodide**.

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