Of the following four groups are `m-` directing when present on a benzene ring. The one which is not meta-directing is:

Options

A. `-COOH`
B. `-NO_(2)`
C. `-CHO`
D. `-NH_(2)`

Explanation

To determine which of the given groups is not meta-directing when present on a benzene ring, we need to analyze the electronic effects of the substituents. Here’s a step-by-step solution:

### Step 1: Understand Directing Effects
- In aromatic chemistry, substituents on a benzene ring can influence the position of new substituents added to the ring during electrophilic aromatic substitution (EAS) reactions.
- There are two main types of directing effects: ortho/para-directing and meta-directing.

### Step 2: Identify Meta-Directing Groups
- Meta-directing groups are typically electron-withdrawing groups (EWGs). They pull electron density away from the benzene ring, making the meta position more favorable for further substitution.
- Common meta-directing groups include:
- Nitro group (-NO2)
- Carbonyl group (-C=O)
- Cyano group (-CN)
- Sulfonyl group (-SO3H)

### Step 3: Identify Ortho/Para-Directing Groups
- Ortho/para-directing groups are generally electron-donating groups (EDGs). They donate electron density to the benzene ring, making the ortho and para positions more favorable for substitution.
- Common ortho/para-directing groups include:
- Alkyl groups (-R)
- Hydroxyl group (-OH)
- Alkoxy group (-O-R)
- Amino group (-NH2)

### Step 4: Analyze the Given Groups
- Without the specific groups listed in the question, we can’t directly identify which one is not meta-directing. However, we can summarize:
- If any of the groups listed is an electron-donating group (like -OH, -NH2, or alkyl groups), it will not be meta-directing.

### Step 5: Conclusion
- To answer the question, identify the groups provided and determine if they are electron-withdrawing or electron-donating. The one that is electron-donating will be the group that is not meta-directing.