Which of the following haloalkanes reacts with aqueous KOH most

easily? Explain giving reason.

1.   I-bromobutane
2.   2bromobutane

3.  2-bromo-2-methylpropane
4.  2-chlorobutane


2-bromo-2-methylpropane (ii), is a tertiary alkyl halicle and Here there is formation of most stable carbocation that is tertiary carbocation on hetrolytic cleavage of C-Br bond.

                Br                                                                                           CH3
                 |                                                                                              |
H3C   C    CH3 -Br-lonisation H3CC+CH3 OH CH3CCH3
                 |                                                     |                                       |
               CH3                                               CH3                                 OH
2-bromo-2- methylpropane               3° carbocation (stable)       2-methyl-2 propanal

While as 4-bromobutane is primary alkyl halide and 2-bromobutane and 2-chlorobutane both are secondary alkyl halide So here There is a possibility of less stable carbocation formation.