Which of the following is ortho-para directing group

Options

A. `CF_(3)`
B. `C Cl_(3)`
C. `-CH=CH -COOH`
D. `-N equiv C`

Answer

To determine which of the given groups is ortho-para directing, we need to analyze the electron-donating or withdrawing nature of each group. Here’s a step-by-step breakdown of the reasoning:

### Step 1: Identify the Groups
We have four groups to analyze:
1. CF3 (Trifluoromethyl)
2. CCl3 (Trichloromethyl)
3. CH=CH-COOH (Acrylic acid)
4. N(CH3)3 (Trimethylamine)

### Step 2: Analyze CF3
- **Nature**: CF3 is a strong electron-withdrawing group due to the electronegativity of fluorine atoms.
- **Effect**: It decreases electron density on the aromatic ring, making it meta-directing.
- **Conclusion**: CF3 is not ortho-para directing.

### Step 3: Analyze CCl3
- **Nature**: CCl3 is also an electron-withdrawing group, similar to CF3.
- **Effect**: It reduces electron density on the ortho and para positions, leading to meta-directing behavior.
- **Conclusion**: CCl3 is not ortho-para directing.

### Step 4: Analyze CH=CH-COOH
- **Nature**: The double bond (C=C) and the carboxylic acid (COOH) can stabilize positive charges through resonance.
- **Effect**: When an electrophile attacks the ortho or para positions, the positive charge can be stabilized by resonance with the double bond and the carboxylic acid group.
- **Conclusion**: CH=CH-COOH is ortho-para directing.

### Step 5: Analyze N(CH3)3
- **Nature**: N(CH3)3 is a nitrogen atom with sp³ hybridization, which has a high s-character and is more electronegative.
- **Effect**: It withdraws electron density from the aromatic ring, making it meta-directing.
- **Conclusion**: N(CH3)3 is not ortho-para directing.

### Final Conclusion
The only group that is ortho-para directing among the options is **CH=CH-COOH**.

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