Answer to Question #309244 in Organic Chemistry for Shahid

Question

Which alkyl halide is more reactive to form alkane

Answer 1

In reactions that adopt the SN1 process, 3o-alkyl halides would be more reactive than their 2o and 1o counterparts. This is contradictory to the reactivity order for the SN2 process that was observed. By either mechanism, allylic and benzylic halides are highly reactive. The alkyl halide reactivity order is RI > RBr > RCl. In terms of the existence of the C-X bond, which is a strongly polarised covalent bond due to the large difference in the electronegativities of carbon and halogen atoms, the high reactivity of alkyl halides can be clarified.

The nucleophile attack takes place from the backward direction in the SN2 reaction. Steric obstruction is also one of the key causes in SN2. Since the primary alkyl halide of primary, secondary and tertiary alkyl halides is the least sterically hindered.