The dehydration of malonic acid `CH_(2) (COOH)_(2)` with `P_(4)O_(10)` and heat give

Options

A. carbon monoxide
B. carbon suboxide
C. carbon dioxide
D. all three

Answer

To solve the question regarding the dehydration of malonic acid (CH₂(COOH)₂) with P₄O₁₀ and heat, we can follow these steps:

### Step 1: Understand the Structure of Malonic Acid
Malonic acid has the formula CH₂(COOH)₂. It consists of two carboxylic acid groups (-COOH) attached to a central carbon atom. The structure can be represented as follows:

```
O O
|| ||
H2C-C-C
| |
OH OH
```

### Step 2: Identify the Dehydration Process
Dehydration refers to the removal of water (H₂O) from a compound. In the case of malonic acid, we can remove water molecules from the -COOH groups. Each -COOH group can release one water molecule.

### Step 3: Calculate the Number of Water Molecules Removed
From malonic acid, we can remove two water molecules:
1. One water molecule from one -COOH group (OH and H).
2. Another water molecule from the second -COOH group (OH and H).

### Step 4: Write the Reaction
The dehydration reaction can be represented as:
\[ \text{CH}_2(\text{COOH})_2 \xrightarrow{\text{P}_4\text{O}_{10}, \text{heat}} \text{C}_3\text{O}_2 + 2\text{H}_2\text{O} \]

### Step 5: Identify the Product
After the removal of two water molecules, we are left with a compound that has three carbon atoms and two oxygen atoms. This compound is known as carbon suboxide (C₃O₂).

### Step 6: Conclusion
Thus, the dehydration of malonic acid with P₄O₁₀ and heat yields carbon suboxide (C₃O₂).

### Final Answer
The correct answer is carbon suboxide (option 2).

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