Which of the following methods would you consider to be the best for preparing n-propylbenzene?

Options

A. `C_(6)H_(5)Br+CH_(3)CH_(2)CH_(2)Brunderset(Br_(2)O,Delta)overset(Na)to`
B. `C_(6)H_(6)+CH_(3)CH=CH_(2)underset(250^(@)C)overset(H_(3)PO_(4))to`
C. `C_(6)H_(6)+CH_(3)CH_(2)CH_(2)Clunderset(Heat)overset(AlCl_(3))to`
D. `C_(6)H_(6)+CH_(3)CH_(2)COClunderset(((ii)Clemmenson reduction))overset(AlCl_(3))to`

Answer

D

Explanation

Reaction (1) gives two more products and `CH_(3)CH_(2)CH_(2)-CH_(2)CH_(2)CH_(3)`. In reaction (2) the electrophile is `(CH_(3))_(2)overset(+)(C)H` giving `C_(6)H_(5)CH(CH_(3))_(2)`. In reaction (3) the electrophile is `CH_(3)CH_(2)overset(delta+)(C)H_(2)------Cl------overset(delta-)(A)lCl_(3)` which may rearrange by hydride shift to give a mixture of products: `C_(6)H_(5)CH_(2)CH_(2)CH_(3)` and `C_(6)H_(5)CH(CH_(3))_(2)`. in reaction (4). the electrophile is `CH_(3)CH_(2)overset(+)(C)O`, which is resonance stabilized and hence dows not rearrange giving exculsively `C_(6)H_(5)COCH_(2)CH_(3)` which on reduction gives `C_(6)H_(5)CH_(2)CH_(2)CH_(3)`.