What type of reaction takes place of `(CH_3)_3C-Br` reacts with aqueous sodium hydroxide ?

Options

A. `S_N1` reaction
B. `S_N2` reaction
C. Addition reaction
D. Elimination reaction

Answer

To determine the type of reaction that occurs when `(CH₃)₃C-Br` (tert-butyl bromide) reacts with aqueous sodium hydroxide (NaOH), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactant is `(CH₃)₃C-Br`, which is tert-butyl bromide, a tertiary alkyl halide.
- The reagent is aqueous sodium hydroxide (NaOH), which provides hydroxide ions (OH⁻) in solution.

**Hint**: Recognize the structure of tert-butyl bromide and the nature of the reagent.

2. **Determine the Type of Alkyl Halide**:
- Tert-butyl bromide is a tertiary halide because the carbon atom bonded to the bromine is attached to three other carbon atoms.

**Hint**: Tertiary alkyl halides are more likely to undergo certain types of reactions due to the stability of the carbocation that can form.

3. **Consider the Solvent and Base**:
- The solvent is water, which is a polar protic solvent.
- The presence of a strong base (OH⁻) in a polar protic solvent is significant for determining the reaction pathway.

**Hint**: Polar protic solvents stabilize carbocations and facilitate certain reaction mechanisms.

4. **Identify the Reaction Mechanism**:
- In the case of tertiary alkyl halides in polar protic solvents, the reaction typically proceeds via an SN1 mechanism.
- The first step involves the formation of a carbocation after the bromine leaves. This step is slow and rate-determining.
- The second step involves the attack of the hydroxide ion (OH⁻) on the carbocation to form the final product.

**Hint**: Remember that SN1 reactions involve two steps: carbocation formation and nucleophilic attack.

5. **Write the Reaction**:
- The overall reaction can be summarized as follows:
- `(CH₃)₃C-Br → (CH₃)₃C⁺ + Br⁻` (formation of carbocation)
- `(CH₃)₃C⁺ + OH⁻ → (CH₃)₃C-OH` (nucleophilic attack)
- The final product is tert-butyl alcohol, `(CH₃)₃C-OH`.

**Hint**: The product of the reaction is an alcohol due to the nucleophilic attack by hydroxide.

### Conclusion:
The reaction of `(CH₃)₃C-Br` with aqueous sodium hydroxide is an **SN1 reaction**, leading to the formation of tert-butyl alcohol.