Question

List the following compounds in order of increasing reactivity in an SN2 reaction.

A. 2-Bromo-2-methylbutane, 1-Bromopentane, 2-Bromopentane
B. 1-Bromo-3-methylbutane, 2-Bromo-2-methylbutane, 2-Bromo-3-methylbutane
C. 1-Bromobutane, 1-Bromo-2,2-dimethylpropane, 1-Bromo-2-methylbutane, 1-Bromo-3-methylbutane

Answer 1

In an SN2 reaction, compounds are more reactive when they have less steric hindrance around the carbon with the leaving group. The reactivity increases from tertiary to primary. The given lists are arranged from least to most reactive based on this principle.

Step-by-step explanation:

For an SN2 (bimolecular nucleophilic substitution) reaction, the reactivity of halogenated compounds is influenced by the steric hindrance around the carbon that bears the leaving group. Less steric hindrance means higher reactivity for SN2 reactions due to the easier access for the nucleophile. The order of reactivity in SN2 reactions generally follows: methyl > primary > secondary > tertiary, with tertiary halides being the least reactive due to steric hindrance.

1. 2-Bromo-2-methylbutane (tertiary) < 1-Bromopentane (primary) < 2-Bromopentane (secondary)
2. 1-Bromo-3-methylbutane (primary) < 2-Bromo-3-methylbutane (secondary) < 2-Bromo-2-methylbutane (tertiary)
3. 1-Bromo-2,2-dimethylpropane (tertiary) < 1-Bromo-3-methylbutane (secondary) < 1-Bromo-2-methylbutane (secondary) < 1-Bromobutane (primary)

Answer 2

A- 1-Bromopentane

>2-Bromopentane> 2-Bromo-2-methylbutane

B- 1-Bromo-3-methylbutane>2-Bromo-3-methylbutane> 2-Bromo-2-methylbutane

C- 1-Bromobutane > 1-Bromo-3-methylbutane>1-Bromo-2-methylbutane>1-Bromo-2,2-dimethylpropane

Step-by-step explanation:

We must bear in mind that the ease of SN2 reaction is methyl > primary> secondary> tertiary.

As a result of this all primary alky halides react faster towards SN2 than secondary and tertiary alkyl halides.

Also, compounds that may form more stable carbocations by 1,2- alkyl shifts are less likely to participate in SN2 reaction