NEETChemistryHaloalkanes and Haloarenes
When (R) -2-bromooctane is treated with aqueous NaOH , it undergoes a nucleophilic substitution reaction. Compare its rate of reaction with that of 1-bromooctane under identical conditions, and identify the stereochemical configuration of the major product formed from (R) -2-bromooctane.
Options
- AIt reacts faster than 1-bromooctane and yields (R) -octan-2-ol.
- BIt reacts slower than 1-bromooctane and yields (R) -octan-2-ol.
- CIt reacts slower than 1-bromooctane and yields (S) -octan-2-ol.
- DIt reacts faster than 1-bromooctane and yields (S) -octan-2-ol.
Correct answer
C. It reacts slower than 1-bromooctane and yields (S) -octan-2-ol.
Step-by-step solution
The reaction of an alkyl halide with aqueous NaOH (a strong nucleophile) primarily follows the S _ N 2 mechanism for primary and secondary substrates. Rate comparison: The rate of an S _ N 2 reaction depends on steric hindrance. 1-Bromooctane is a primary ( 1^ ) alkyl halide, whereas 2-bromooctane is a secondary ( 2^ ) alkyl halide. Due to greater steric crowding around the -carbon in the 2^ halide, 2-bromooctane reacts slower than 1-bromooctane. Stereochemistry: The S _ N 2 mechanism proceeds with a complete inver