Question

The relative rates of reaction of ethane, toluene, and ethylbenzene with bromine atoms have been measured.

The most reactive hydrocarbon undergoes hydrogen atom abstraction a million times faster than does the least reactive one.


Arrange these hydrocarbons in order of decreasing reactivity.

Answer 1

Answer:

Reactivity: Ethyl benzene > Toluene > Ethane

Explanation:

The order of reactivity depends on how easily the most reactive hydrogen can be abstracted.

The order of reactivity of hydrogen is : 1° < 2° < 3° < Benzyllic based on the stabilizing effects like inductive effect, hyperconjugation , resonance effect.

• In ethane, all the hydrogen present are 1°.

• In toluene, the most reactive hydrogen is benzyllic.

• In Ethyl Benzene, the most reactive hydrogen is 2° as well as benzyllic.

Hence the order of decreasing reactivity : Ethyl Benzene, Toluene , Ethane.