Identify (Z) in the following sequence of reactions.
`CH_3CH_2COCloverset("HN_3")rarr(X)overset(Delta)rarr(Y)overset(H_2O)rarr(Z)`

Options

A. `CH_3CH_2NCO`
B. `CH_3CH_2NHCOOH`
C. `CH_3CH_2NH_2`
D. `CH_3underset(NH_2)underset(|)(CHCOOH)`

Answer

To identify (Z) in the given sequence of reactions, we will follow the steps outlined in the video transcript.

### Step-by-Step Solution:

1. **Identify the Starting Compound:**
The starting compound is CH₃CH₂COCl (propionyl chloride).

2. **Reaction with HN₃:**
When CH₃CH₂COCl reacts with HN₃ (azide), the nitrogen from HN₃ attacks the carbonyl carbon of the propionyl chloride. The chlorine atom is displaced, leading to the formation of an azide derivative.
- **Product X:** CH₃CH₂C(=O)N₃ (propionyl azide).

3. **Heating Product X:**
Upon heating, the azide group (N₃) decomposes, releasing nitrogen gas (N₂) and forming an intermediate.
- **Product Y:** CH₃CH₂C(=O)NH (propionamide).

4. **Reaction with Water:**
When Product Y (propionamide) reacts with water, the water molecule attacks the carbonyl carbon. The lone pair of electrons on the oxygen in water attacks the carbon, leading to the formation of a hydroxyl group.
- This results in the formation of an intermediate that can be represented as CH₃CH₂C(=O)OH (propionic acid) and NH₂.

5. **Final Product Z:**
After the reaction with water, the proton (H⁺) is removed from the hydroxyl group, resulting in the formation of an amine.
- **Final Product Z:** CH₃CH₂NH₂ (ethylamine).

Thus, the final product (Z) is **ethylamine (CH₃CH₂NH₂)**.

### Summary:
- Starting compound: CH₃CH₂COCl
- Product X: CH₃CH₂C(=O)N₃
- Product Y: CH₃CH₂C(=O)NH
- Final Product Z: CH₃CH₂NH₂