Which is incorrect order of –I effect

Options

A. `F gt Cl gt Br gt I `
B. ` –NR gt –NH gt –NO 332 `
C. ` –OCH3gt –OH gt –NH`
D.

Answer

To determine the incorrect order of the –I (inductive) effect among the given options, we need to understand the concept of the –I effect. The –I effect refers to the electron-withdrawing inductive effect exerted by certain groups or atoms in a molecule. Electron-withdrawing groups pull electron density away from the rest of the molecule, affecting its reactivity and properties.

### Step-by-Step Solution:

1. **Understanding the –I Effect**:
- The –I effect is an electron-withdrawing effect. Groups that exhibit this effect pull electrons towards themselves, making the rest of the molecule more positive (or less electron-rich).
- Common –I groups include halogens (like F, Cl, Br, I), nitro groups (NO2), and cyano groups (CN).

2. **Analyzing the Options**:
- We need to analyze each option provided to identify which one incorrectly represents the order of the –I effect.

3. **Option A**:
- The order given is: Plurin (P) > Bromine (Br) > Iodine (I).
- This order is correct because Plurin is a stronger electron-withdrawing group than Bromine, and Bromine is stronger than Iodine due to their electronegativity and size.

4. **Option B**:
- The order given is: NR > NH > NO3.
- This order is incorrect. The NR group is actually an electron-donating group, while NO3 is a strong electron-withdrawing group. The correct order should be NO3 > NH > NR.

5. **Option C**:
- The order given is: OH3 > OH > NH.
- This order is correct. The –I effect of OH3 (alkoxyl group) is stronger than that of OH, which is stronger than NH.

6. **Option D**:
- The order given is: Toluene (C6H5CH3) > Ethyne (C2H2) > Hydrogen (H).
- This order is also correct. Toluene has a –I effect due to the presence of the phenyl group, which is stronger than Ethyne, and Ethyne is stronger than Hydrogen.

7. **Conclusion**:
- The incorrect order of the –I effect is found in **Option B**.

### Final Answer:
The incorrect order of –I effect is **Option B: NR > NH > NO3**.