Express in decreasing order of `(+ I) - `
`(a) CH_(3)CH_(2) - CH_(2) - " " (b) CH_(3) - `
`(c) CH_(3)-underset(|)overset(CH_(3))overset(|) C-CH_(2)-CH_(3)" "(d) CH_(3) - underset(CH_(3))underset(|) overset(CH_(3))overset(|)C - `
`(e) CH_(3) - underset(CH_(2)CH_(3)" ")underset(|" ")(CH - CH_(2))- `
Correct answer is -

Options

A. `(c) gt (d) gt (e) gt (a) gt (b) `
B. `(d) gt (a) gt(b) gt (c) gt (e) `
C. `(a) gt (b) gt (c) gt (d) gt (e) `
D. `(a) gt (b) gt (c) gt (e) gt (d) `

Answer

To express the compounds in decreasing order of the +I effect, we need to analyze the structure of each compound and determine the strength of the +I effect based on the number of alkyl groups attached to the carbon atoms. The +I effect is influenced by the number of carbon atoms (alkyl groups) attached to the carbon in question, with tertiary carbons having the strongest +I effect, followed by secondary, and then primary carbons.

Let's analyze each compound step by step:

1. **Identify the Compounds**:
- (a) CH₃CH₂-CH₂- (Primary)
- (b) CH₃- (Primary)
- (c) CH₃-CH(CH₃)-C-CH₂-CH₃ (Tertiary)
- (d) CH₃-CH(CH₃)-C- (Tertiary)
- (e) CH₃-CH₂-CH(CH₃)-CH₂- (Secondary)

2. **Determine the Type of Carbon**:
- (a) CH₃CH₂-CH₂-: This is a primary carbon chain with no branching.
- (b) CH₃-: This is a primary carbon.
- (c) CH₃-CH(CH₃)-C-CH₂-CH₃: The central carbon is tertiary due to two methyl groups attached.
- (d) CH₃-CH(CH₃)-C-: The central carbon is also tertiary.
- (e) CH₃-CH₂-CH(CH₃)-CH₂-: The central carbon is secondary.

3. **Rank the +I Effects**:
- Tertiary carbons (c and d) will have the strongest +I effect.
- Secondary carbon (e) will have a moderate +I effect.
- Primary carbons (a and b) will have the weakest +I effect.

4. **Order of +I Effect**:
- (c) > (d) > (e) > (a) > (b)

5. **Final Decreasing Order**:
- The final order of the compounds in terms of decreasing +I effect is:
- (c) > (d) > (e) > (a) > (b)