Which of the following is correct with respect to -|-effect of the substituents? (R = alkyl)

Options

A. `-NH_2 lt - OR lt - F`
B. `-NR_2 lt - OR lt -F`
C. `-NH_2 gt - OR lt -F`
D. `-NR_2 gt - OR gt -F`

Explanation

To solve the question regarding the -I (minus inductive) effect of substituents, we will analyze the electronegativity of the given groups and their influence on the -I effect.

### Step-by-Step Solution:

1. **Understanding the -I Effect**:
- The -I effect refers to the ability of a substituent to withdraw electron density from the rest of the molecule through sigma bonds. This is primarily influenced by the electronegativity of the substituent.

2. **Electronegativity Order**:
- The electronegativity of different elements can be ranked. In this case, we will consider the groups mentioned:
- Fluorine (F) has the highest electronegativity.
- Oxygen (O) is next.
- Nitrogen (N) follows.
- Alkyl groups (R) have a relatively low electronegativity and are often considered as electron-donating groups.

3. **Ranking the Groups**:
- Based on electronegativity, we can rank the groups in terms of their -I effect:
- F > O > N > R (alkyl group)
- This means that the -I effect is strongest for fluorine and weakest for alkyl groups.

4. **Comparing the Options**:
- From the ranking, we can derive the following relationships:
- -NR2 (where R is an alkyl group) has a weaker -I effect than -OR and -F.
- Therefore, the order can be summarized as:
- -NR2 < -OR < -F
- We can also express this in reverse order for clarity:
- -F > -OR > -NR2

5. **Evaluating the Given Options**:
- We will compare the provided options with our derived order.
- If the options match the derived order, they are correct.

### Conclusion:
- The correct options regarding the -I effect of the substituents are those that align with the order we established: -F > -OR > -NR2.