`"Acetaldehyde"overset(HCN)toXoverset(H_(2)O //H^(+))toYoverset("Heat")toZ`
In the above sequence, the end product Z is

Options

A. Prop-2-enoic acid
B. But-2-enoic acid
C. Lactic acid
D. Tartaric acid

Answer

To solve the problem step by step, we will analyze the reaction sequence involving acetaldehyde and determine the final product Z.

### Step 1: Identify Acetaldehyde
Acetaldehyde is represented by the formula CH₃CHO. It has a carbonyl group (C=O) and is the simplest aldehyde.

### Step 2: Reaction with HCN
When acetaldehyde reacts with hydrogen cyanide (HCN), the cyanide ion (CN⁻) acts as a nucleophile and attacks the carbonyl carbon of acetaldehyde. This results in the formation of a cyanohydrin. The reaction can be summarized as follows:

\[ \text{CH}_3CHO + \text{HCN} \rightarrow \text{CH}_3C(OH)(CN) \]

This compound is referred to as the cyanohydrin, which we will label as X.

### Step 3: Acidic Hydrolysis
Next, we treat the cyanohydrin (X) with water (H₂O) in the presence of an acid (H⁺). This process is known as acidic hydrolysis. During this reaction, the CN group is converted into a carboxylic acid (COOH). The reaction can be represented as:

\[ \text{CH}_3C(OH)(CN) + H_2O/H^+ \rightarrow \text{CH}_3C(OH)(COOH) \]

This product is now labeled as Y, which is 2-hydroxybutanoic acid (or hydroxybutyric acid).

### Step 4: Heating the Product
The next step involves heating the compound Y. When heated, a dehydration reaction occurs where a water molecule is eliminated. This leads to the formation of a double bond between the carbon atoms. The reaction can be summarized as follows:

\[ \text{CH}_3C(OH)(COOH) \xrightarrow{\text{Heat}} \text{CH}_2=C(COOH) \]

This product is now labeled as Z.

### Step 5: Naming the Final Product
The final product Z can be identified as prop-2-enoic acid (also known as acrylic acid). The structure shows a double bond between the second and third carbon atoms, with a carboxylic acid group at one end.

### Conclusion
Thus, the end product Z is **prop-2-enoic acid**.

### Final Answer
The end product Z is **prop-2-enoic acid**.

---