An alkane C_8H_18 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 structures of alkane and the tertiary bromide.

An alkane C_8H_18 is obtained as the only product on subjecting a prim

1.	An alkane C_8H_18 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 structures of alkane and the tertiary bromide.
Answer» Solution :(i)We know that Wurtz reaction of an alkyl halide gives an alkane with DOUBLE the number of carbon ATOMS present in the alkyl halide. Since hereWurtz reaction of a primary of a primary alkyl halide gives an alkane with M.F. `C_8H_18`, therefore , the `1^@` alkyl halide MUST contain four carbon atoms. Now the two possible primary alkyl halides having four carbon atoms each are I and II. `underset"I"(CH_3CH_2CH_2CH_2-X) "" underset"II"(CH_3-oversetoverset(CH_3)\|CH-CH_2X)` (ii)Since the alkane `C_8H_18` on MONOBROMINATION yields a single isomer of a tertiary alkyl halide, therefore, the alkene `C_8H_18` must contain a tertiary hydrogen. This is possible only if the starting primary alkyl halide has a tertiary hydrogen. Out of I and II , onlyprimary alkyl halide (II) has a tertiary hydrogen. In other WORDS, the starting primary alkyl halide is 1-halo-2-methylpropane (II). If this is so, then the alkene with M.F. `C_8H_18` must be 2,5-dimetylhexane (III) and the monobromoderivative must be 2-bromo-2,5-dimethylhexane (IV).