Glycerol `to KHSO_4 [A] to LiAlH_4 [B]` which of the following is
not B

Options

A. Allyl alcohol
B. Acrolein
C. Acrylic acid
D. None of these

Explanation

To solve the problem step by step, we need to analyze the reactions that occur when glycerol is treated with KHSO4 and then with LiAlH4.

### Step 1: Understanding Glycerol
Glycerol (C3H8O3) has the following structure:
```
CH2OH
|
CH
|
CH2OH
```
It contains three hydroxyl (-OH) groups.

### Step 2: Reaction with KHSO4
When glycerol is treated with KHSO4, which is a dehydrating agent, it removes water molecules. The reaction can be summarized as follows:
- **Dehydration Reaction**: Glycerol loses two water molecules (H2O) to form an intermediate compound.

The reaction can be represented as:
```
Glycerol (C3H8O3) → Acrolein (C3H4O) + H2O
```
The product formed here is acrolein (CH2=CH-CHO), which is unstable and will undergo tautomerization.

### Step 3: Tautomerization of Acrolein
Acrolein can tautomerize to form:
```
CH2=CH-CHO (Acrolein) ↔ CH2=CH-COH (unstable form)
```
However, acrolein itself is the primary product formed from the dehydration of glycerol.

### Step 4: Reaction with LiAlH4
Next, acrolein reacts with lithium aluminium hydride (LiAlH4), which is a strong reducing agent. The reaction can be summarized as follows:
- **Reduction Reaction**: Acrolein is reduced to form allyl alcohol.

The reaction can be represented as:
```
Acrolein (C3H4O) + LiAlH4 → Allyl Alcohol (C3H6O)
```
The product formed here is allyl alcohol (CH2=CH-CH2OH).

### Step 5: Identifying the Products
Now, we need to identify which of the given options is not product B. Based on the reactions:
- A (the product after KHSO4) is acrolein.
- B (the product after LiAlH4) is allyl alcohol.

### Conclusion
From the options provided, we can conclude:
- Acrolein is product A.
- Allyl alcohol is product B.
- Any compound that is not allyl alcohol is the answer to the question.

Thus, the answer to the question "which of the following is not B" is **acrylic acid**, as it is not formed in the reaction sequence.