Question

To prepare a pure sample of n-hexane using sodium metal as one reactant, the other reactant will be

• A. n-propyl bromide
• B. Ethyl bromide and n-butyl bromide
• C. Ethyl chloride and n-butyl chloride
• D. Methyl bromide and n -pentyl chloride

Answer 1

The correct option is A n-propyl bromide

According to wurtz reaction, the alkyl groups in the alkyl halides will combine to form an alkane. In this case however, we have multiple possible options.
But remember that if you use propyl halides, only hexane will be produced. Other alkyl halides will cause unwanted dimer products. For example, ethyl halide with butyl halide will give 3 products- Butane, Hexane and Octane.
The reaction can be summarised as:
$2C{H}_{3}C{H}_{2}C{H}_{2}Br+2Na\stackrel{ether}{\to }C{H}_3(C{H}_2{)}_{4}C{H}_3+2NaBr$