The best method to prepare 3-methylbutane-2-ol from 3-methylbut-1-ene is

Options

A. addition of water in presence of dil. `H_(2)SO_(4)`
B. addition of HCl followed by reaction with dil. NaOH
C. hydroboration -oxidation reaction
D. Reimer-Tiemann reaction .

Explanation

To prepare 3-methylbutane-2-ol from 3-methylbut-1-ene, we can analyze the given options step by step:

### Step 1: Identify the structure of the reactant and product
- The reactant is **3-methylbut-1-ene**, which can be represented as:
\[ CH_3-CH(CH_3)-CH=CH_2 \]
- The product we want to synthesize is **3-methylbutane-2-ol**, represented as:
\[ CH_3-CH(OH)-CH(CH_3)-CH_3 \]

### Step 2: Analyze the first option: Addition of water in the presence of dilute H2SO4
- In this method, water (H2O) is added to the alkene in the presence of dilute sulfuric acid (H2SO4).
- According to **Markovnikov's rule**, the hydrogen (H) will add to the carbon with more hydrogen atoms, and the hydroxyl group (OH) will add to the carbon with fewer hydrogen atoms.
- Therefore, the addition of water will yield:
\[ CH_3-CH(OH)-CH(CH_3)-CH_3 \]
- This matches our desired product, **3-methylbutane-2-ol**.

### Step 3: Analyze the second option: Addition of HCl followed by reaction with dilute NaOH
- When HCl is added to the alkene, a carbocation is formed. The more stable carbocation (secondary or tertiary) will form.
- However, this reaction can lead to rearrangement, potentially resulting in a different product than desired.
- After reacting with NaOH, the final product is likely to be **2-methyl-2-butanol**, which is not our target.

### Step 4: Analyze the third option: Hydroboration-oxidation
- Hydroboration involves the addition of BH3 followed by oxidation with H2O2 and NaOH.
- This reaction follows **anti-Markovnikov's rule**, where the hydrogen adds to the less substituted carbon.
- The product formed would be **2-methyl-2-butanol**, which is again not the desired product.

### Step 5: Analyze the fourth option: Riemann-Tiemann reaction
- This reaction involves the use of chloroform and a strong base, leading to the formation of a different type of alcohol.
- The product does not match our desired structure of **3-methylbutane-2-ol**.

### Conclusion
The best method to prepare **3-methylbutane-2-ol** from **3-methylbut-1-ene** is the **first option: addition of water in the presence of dilute H2SO4**.