How are alcohols prepared from haloalkanes ?

Options

A. By treating with concentrated `H_2SO_4`
B. By heating with aqueous NaOH
C. By treating with a strong reducing agent
D. By treating with Mg metal

Answer

To prepare alcohols from haloalkanes, we can follow a systematic approach. Here’s a step-by-step solution:

### Step 1: Understanding Haloalkanes
Haloalkanes (alkyl halides) are organic compounds containing carbon, hydrogen, and halogen atoms. The general formula for haloalkanes is R-X, where R is an alkyl group and X is a halogen (F, Cl, Br, I).

### Step 2: Choosing the Method of Preparation
There are several methods to convert haloalkanes to alcohols. The most common methods include:
1. **Nucleophilic Substitution Reactions**
2. **Reduction Reactions**

### Step 3: Nucleophilic Substitution Reaction
One of the most straightforward methods to prepare alcohols from haloalkanes is through nucleophilic substitution reactions, typically using hydroxide ions (OH⁻) or water (H₂O) as nucleophiles.

#### Example Reaction:
- **Using Sodium Hydroxide (NaOH)**:
\[ R-X + NaOH \rightarrow R-OH + NaX \]
Here, the hydroxide ion attacks the carbon atom bonded to the halogen, resulting in the formation of an alcohol (R-OH) and a sodium halide (NaX).

### Step 4: Reduction Reactions
Another method involves the reduction of haloalkanes using reducing agents.

#### Example Reaction:
- **Using Zinc and Water (Zn/H₂O)**:
\[ R-X + Zn + H₂O \rightarrow R-OH + ZnX \]
In this reaction, the haloalkane is reduced to an alcohol, where the halogen is replaced by a hydroxyl group.

### Step 5: Grignard Reagent Method
Grignard reagents can also be used to prepare alcohols from haloalkanes.

#### Example Reaction:
- **Using Grignard Reagents**:
\[ R-X + RMgX \rightarrow R-OH \]
Here, the Grignard reagent (RMgX) reacts with the haloalkane, leading to the formation of an alcohol after hydrolysis.

### Conclusion
In summary, alcohols can be prepared from haloalkanes through nucleophilic substitution reactions using hydroxide ions or water, reduction reactions with reducing agents, or by using Grignard reagents followed by hydrolysis.

---