`RCH = CH_(2)` adds on water in the presence of dilute sulphuric acid or phosphoric acid to form

Options

A. `R – CH(OH)–CH_(3)`
B. `R – CH_(2) – CH_(2)OH`
C. `R – CHOH – CH_(2)– CH_(2)– CHOH –R`
D. `R-underset(OH)underset(|)(CH)-underset(OH)underset(|)(CH_(2))`

Answer

To solve the question about the reaction of RCH=CH₂ with water in the presence of dilute sulfuric acid or phosphoric acid, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
The reactant is an alkene, RCH=CH₂, which has a double bond between the carbon atoms.

**Hint**: Recognize that alkenes are reactive due to their double bonds.

2. **Reaction Conditions**:
The reaction occurs in the presence of dilute sulfuric acid (H₂SO₄) or phosphoric acid (H₃PO₄). These acids will protonate the alkene.

**Hint**: Understand that acids can donate protons (H⁺) which can initiate the reaction.

3. **Protonation of the Alkene**:
The double bond in the alkene acts as a nucleophile and attacks the proton (H⁺) from the acid. This leads to the formation of a carbocation intermediate.

**Hint**: Remember that the more stable carbocation will form preferentially.

4. **Formation of Carbocation**:
The protonation occurs at the less substituted carbon (if R is a larger group), leading to the formation of a more stable carbocation at the other carbon.

**Hint**: Stability of carbocations is key; tertiary > secondary > primary.

5. **Nucleophilic Attack by Water**:
Water (H₂O) acts as a nucleophile and attacks the carbocation, leading to the formation of an alcohol.

**Hint**: Water can donate a pair of electrons to form a bond with the carbocation.

6. **Deprotonation**:
The final step involves the deprotonation of the oxonium ion (the intermediate formed after water attacks the carbocation) to yield the final alcohol product.

**Hint**: Look for the removal of a proton (H⁺) to stabilize the alcohol.

7. **Final Product**:
The final product is R-CHOH-CH₃, which is a secondary alcohol.

**Hint**: Identify the structure of the product to confirm it is a secondary alcohol.

### Final Answer:
The product formed from the reaction of RCH=CH₂ with water in the presence of dilute sulfuric acid or phosphoric acid is R-CHOH-CH₃, a secondary alcohol.