Question

36. An alkane c8h18 is obtained as the only product on subjecting a primary alkyl halide to wurtz reaction. On monobromination this alkane yields a single isomer of a tertiary bromide. Write the structure of alkane and the tertiary bromide.

Answer 1

An alkane obtained from Wurtz reaction from a primary alkyl halide must be simmetrical, obtained from 2 molecules of 1-halogen-2-methyl-propane:

2 (H3C)2CHCH2X + 2 Na → (H3C)2CHCH2CH2CH(CH3)2

The monobromination of this alkane gives

2-bromo-5-methyl-hexane:

2 (H3C)2CHCH2CH2CH2(CH3)2 +Br2 →

2 (H3C)2CBrCH2CH2CH(CH3)2

The bromination involves C2 because the intermediate radical is a more stable tertiary radical