Which of the following acids on heating loses a molecul of `H_(2)O` to form an `alpha,beta`-unsaturated acid?

Options

A. `CH_(3)CHOHCOOH`
B. `HOCH_(2)COOH`
C. `CH_(3)CHOHCH_(2)COOH`
D. `HOCH_(2)CH_(2)CH_(2)COOH`

Explanation

To determine which of the given acids loses a molecule of water upon heating to form an alpha, beta-unsaturated acid, we need to analyze each option systematically. Here’s the step-by-step solution:

### Step 1: Understand the Structure of Alpha, Beta-Unsaturated Acids
Alpha, beta-unsaturated acids are characterized by a double bond between the alpha and beta carbon atoms adjacent to the carboxylic acid group. The general structure can be represented as:
- R-CH=CH-COOH
Where R can be a hydrogen or any alkyl group.

### Step 2: Analyze Each Acid Option
Let’s denote the acids as follows for clarity:
1. Acid A: R1-CHOH-COOH
2. Acid B: R2-CH2OH-COOH
3. Acid C: R3-CH(OH)-CH2-COOH
4. Acid D: R4-CH2-CH2-COOH

We will analyze each option to see if heating leads to the loss of water (H2O) and the formation of an alpha, beta-unsaturated acid.

### Step 3: Evaluate Acid A
For Acid A (R1-CHOH-COOH):
- Upon heating, the hydroxyl group (OH) from the alpha carbon can combine with a hydrogen atom from the beta carbon to form water (H2O).
- This results in the formation of R1-CH=COOH, which is an alpha, beta-unsaturated acid.

### Step 4: Evaluate Acid B
For Acid B (R2-CH2OH-COOH):
- Similar to Acid A, upon heating, the OH group can lose a hydrogen atom from the adjacent carbon, resulting in the formation of R2-CH=COOH, which is also an alpha, beta-unsaturated acid.

### Step 5: Evaluate Acid C
For Acid C (R3-CH(OH)-CH2-COOH):
- Upon heating, the OH group can again lose a hydrogen atom from the adjacent carbon, leading to the formation of R3-CH=CH-COOH, which is an alpha, beta-unsaturated acid.

### Step 6: Evaluate Acid D
For Acid D (R4-CH2-CH2-COOH):
- In this case, there is no hydroxyl group on the alpha or beta carbon. Thus, it cannot lose water to form an alpha, beta-unsaturated acid.

### Conclusion
From the analysis, Acids A, B, and C can lose a molecule of water upon heating to form alpha, beta-unsaturated acids. However, Acid D does not have the necessary structure to undergo this reaction.

### Final Answer
The correct options that can form alpha, beta-unsaturated acids upon heating are:
- Acid A, Acid B, and Acid C.