Arrange the following alkenes towards order of increasing reactivity towards an cationic polymerization
(i) `CH_(2)=CH_(2)` (2) `CH_(2)=CHCN` (3) `CH_(2) = CH-CH_(3)` (4) `CH_(2)=CH-OCH_(3)`

Options

A. `4 gt 3 gt 1 gt 2`
B. `2 gt 1 gt 4 gt 3`
C. `2gt 1 gt 3 gt 4`
D. `1 gt 3 gt 2 gt 4`

Explanation

To determine the order of increasing reactivity of the given alkenes towards cationic polymerization, we need to analyze the stability of the carbocations that would form during the polymerization process. The stability of these carbocations is influenced by various effects such as hyperconjugation and resonance.

### Step-by-Step Solution:

1. **Identify the Alkenes**:
- (i) `CH₂=CH₂` (Ethylene)
- (ii) `CH₂=CHCN` (Acrylonitrile)
- (iii) `CH₂=CH-CH₃` (Propylene)
- (iv) `CH₂=CH-OCH₃` (Vinyl methyl ether)

2. **Understand Cationic Polymerization**:
- Cationic polymerization involves the formation of a carbocation from the alkene. The stability of this carbocation will determine the reactivity of the alkene in the polymerization process.

3. **Evaluate Carbocation Stability**:
- **Ethylene (i)**: Forms a primary carbocation, which is the least stable.
- **Acrylonitrile (ii)**: The cyano group (–CN) exerts a -I (inductive) effect, destabilizing the carbocation.
- **Propylene (iii)**: Forms a secondary carbocation, which is more stable than a primary carbocation due to hyperconjugation.
- **Vinyl methyl ether (iv)**: The methoxy group (–OCH₃) can donate electron density through resonance (+M effect), stabilizing the carbocation significantly.

4. **Rank the Alkenes**:
- The order of stability of the carbocations formed from these alkenes is:
- (iv) `CH₂=CH-OCH₃` (most stable due to resonance)
- (iii) `CH₂=CH-CH₃` (secondary carbocation)
- (i) `CH₂=CH₂` (primary carbocation)
- (ii) `CH₂=CHCN` (least stable due to -I effect from CN)

5. **Final Order of Increasing Reactivity**:
- Therefore, the order of increasing reactivity towards cationic polymerization is:
- (ii) `CH₂=CHCN` < (i) `CH₂=CH₂` < (iii) `CH₂=CH-CH₃` < (iv) `CH₂=CH-OCH₃`

### Conclusion:
The final order of increasing reactivity towards cationic polymerization is:
**(ii) < (i) < (iii) < (iv)**