The compounds which cannot react with NaOH is/are

Options

A. (a) `CH_(3)-C-=CH`
B. (b) `NH_(3)`
C. (c) `C_(2)H_(5)OH`
D. (d)

Answer

To determine which compound cannot react with NaOH, we need to analyze the acidity of the compounds provided. NaOH is a strong base and typically reacts with acidic compounds by deprotonating them to form their conjugate bases. Let's evaluate each option step by step.

### Step 1: Analyze Compound A (e.g., Alkyne)
- **Structure**: Let's assume compound A is an alkyne, such as CH≡C-CH3.
- **Reaction with NaOH**: The most acidic hydrogen is the one attached to the terminal carbon of the alkyne. When NaOH is added, it can remove this hydrogen, forming a stable conjugate base (CH≡C-).
- **Conclusion**: Compound A can react with NaOH.

**Hint**: Look for the most acidic hydrogen in the compound and consider the stability of the resulting conjugate base.

### Step 2: Analyze Compound B (e.g., Ammonia, NH3)
- **Structure**: NH3 (Ammonia).
- **Reaction with NaOH**: When NH3 reacts with NaOH, it can lose a hydrogen ion (H+) to form NH2-. However, NH2- is not a stable anion compared to other conjugate bases.
- **Conclusion**: Compound B (NH3) does not react with NaOH effectively because it does not want to lose its H+ ion.

**Hint**: Consider the stability of the conjugate base formed after deprotonation.

### Step 3: Analyze Compound C (e.g., Ethanol, C2H5OH)
- **Structure**: C2H5OH (Ethanol).
- **Reaction with NaOH**: Ethanol has an acidic hydrogen on the hydroxyl group. When NaOH is added, it can remove this hydrogen, forming the ethoxide ion (C2H5O-), which is stable due to the electronegativity of oxygen.
- **Conclusion**: Compound C can react with NaOH.

**Hint**: Check if the negative charge on the conjugate base is stabilized by electronegative atoms.

### Step 4: Analyze Compound D (e.g., Phenol)
- **Structure**: C6H5OH (Phenol).
- **Reaction with NaOH**: Phenol also has an acidic hydrogen on the hydroxyl group. When NaOH is added, it can remove this hydrogen, forming the phenoxide ion (C6H5O-). This anion is stabilized by resonance with the aromatic ring.
- **Conclusion**: Compound D can react with NaOH.

**Hint**: Look for resonance stabilization in the conjugate base, especially in aromatic compounds.

### Final Conclusion
Based on the analysis:
- Compound A (Alkyne) reacts with NaOH.
- Compound B (Ammonia) does not react with NaOH.
- Compound C (Ethanol) reacts with NaOH.
- Compound D (Phenol) reacts with NaOH.

Thus, the compound that cannot react with NaOH is **Compound B (Ammonia, NH3)**.