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.

BrCH3
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H3CCCH3-Br-lonisationH3CC+CH3OHCH3CCH3
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CH3CH3OH
2-bromo-2-methylpropane3°carbocation(stable)2-methyl-2propanal

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.