The order of rate of hydrolysis of alkyl halides `1^(@),2^(@),3^(@)` and `CH_(3)X` by the `S_(N^(2))` pathway is :

Options

A. `1^@gt2^@gt3^@gtCH_3X`
B. `CH_3Xgt3^@gt2^@gt1^@`
C. `CH_3Xgt1^@gt2^@gt3^@`
D. `3^@gt2^@gt1^@CH_3X`

Answer

To determine the order of the rate of hydrolysis of alkyl halides (1°, 2°, 3°, and CH₃X) by the SN2 pathway, we need to consider the factors that influence the SN2 reaction mechanism.

### Step-by-step Solution:

1. **Understanding SN2 Mechanism**:
- The SN2 (Substitution Nucleophilic Bimolecular) reaction involves a nucleophile attacking the electrophilic carbon atom of the alkyl halide, leading to the displacement of the leaving group. This reaction occurs in a single concerted step.

2. **Steric Hindrance**:
- The rate of an SN2 reaction is significantly affected by steric hindrance around the carbon atom that is being attacked by the nucleophile. The more crowded the carbon atom is, the slower the reaction will be.

3. **Analyzing Different Alkyl Halides**:
- **Methyl Halide (CH₃X)**: There is no steric hindrance, making it the most reactive in SN2 reactions.
- **Primary Alkyl Halides (1°)**: Slight steric hindrance, but still relatively reactive.
- **Secondary Alkyl Halides (2°)**: More steric hindrance than 1°, thus less reactive compared to 1°.
- **Tertiary Alkyl Halides (3°)**: The most steric hindrance, making them the least reactive in SN2 reactions.

4. **Order of Reactivity**:
- Based on the analysis of steric hindrance, the order of reactivity for hydrolysis of alkyl halides by the SN2 pathway is:
- CH₃X > 1° > 2° > 3°

5. **Final Conclusion**:
- Therefore, the order of rate of hydrolysis of alkyl halides by the SN2 pathway is: **CH₃X > 1° > 2° > 3°**.