Question

Arrange the alkyl halides in order of reactivity from most to least with AgNo3/Ethanol:

1) 2-bromobutane

2) 2-bromo-2-methyl pentane

3) 1-bromobutane

4) bromocyclohexane thank you

Answer 1

The reaction of haloalkane with AgNo3 /ethanol will take place via formation of carbonation. As we know greater the stability of the carbocation formed higher will be the reactivity. The order of stability of carbocation is:

3° > 2° >1°.

Because the alkyl group bonded to the positively charged carbon shows the electron releasing effect and thus make the carbocation more stable.

In 1) 2° carbocation will be formed when Br- is lost.

In 2)3° carbocation is formed.

In 3) 1° carbocation is formed.

In 4) cyclic 2° carbocation is formed.

Since cyclic cation will be more stable than primary but less than secondary . So the order of reactivity is:

2 > 1> 4 > 3