Question: Write the names of alkyl halide and sodium alkoxide used to prepare tert-butyl ethyl ether.
Step 1 (Governing Principle - Williamson Synthesis): [0.5 Mark]
According to the Williamson ether synthesis, an ether is prepared by the reaction of an alkyl halide with a sodium alkoxide. To avoid the formation of alkenes via elimination (as tertiary halides undergo $E2$ elimination), the alkyl halide must be primary ($1^\circ$) and the alkoxide should be tertiary ($3^\circ$) if the target ether is bulky.
The reaction follows the general equation:
$$R-X + R'-ONa \rightarrow R-O-R' + NaX$$Step 2 (Step-by-Step Deduction): [0.25 Mark]
To prepare tert-butyl ethyl ether ($CH_3-C(CH_3)_2-O-CH_2-CH_3$), we must choose the reactants such that the nucleophilic attack occurs on the primary alkyl halide:
- Alkyl Halide: Ethyl halide (e.g., Ethyl bromide or Ethyl chloride)
- Sodium Alkoxide: Sodium tert-butoxide
Reaction: $$CH_3CH_2Br + (CH_3)_3CONa \rightarrow (CH_3)_3C-O-CH_2CH_3 + NaBr$$
Step 3 (Final Concluded Answer): [0.25 Mark]
The required reactants are:
- Alkyl halide: Ethyl bromide (or Ethyl chloride)
- Sodium alkoxide: Sodium tert-butoxide
💡 EL10 Concept Insight: Think of this like a puzzle: if you try to use a bulky "tert-butyl" piece as the halide, it’s too crowded and will just break apart (elimination) instead of connecting. By using the small "ethyl" piece as the halide, it can easily slide in and attach to the bulky "tert-butoxide" piece to form the ether successfully!