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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: georgetian3 on January 09, 2019, 07:18:02 PM

Title: USNCO 2014 Q58 - comparing rate of SN1 vs SN2 reactions
Post by: georgetian3 on January 09, 2019, 07:18:02 PM
The reaction between which pair of reactants occurs the fastest for [OH-] = 0.010 M?

(A) CH3CH2CH2CH2Cl + OH-
(B) (CH3)3CCl + OH-
(C) CH3CH2CH2CH2Br + OH-
(D) (CH3)3CBr + OH

First looking at the leaving group, Br- is a better leaving group than Cl-, hence options A) and B) were removed.

I then thought that, as OH- is a strong base and a strong nucleophile, the reaction should occur through SN2 pathway, which is fastest in primary alkyl halides, hence C)

However, the answers state D). Why would this be faster?
Title: Re: USNCO 2014 Q58 - comparing rate of SN1 vs SN2 reactions
Post by: AWK on January 10, 2019, 04:16:04 AM
Some compounds react through E1 pathway.
Title: Re: USNCO 2014 Q58 - comparing rate of SN1 vs SN2 reactions
Post by: Babcock_Hall on January 10, 2019, 08:27:53 AM
It may be that the problem is getting at the rate laws for SN1 vs. SN2.  The same logic holds for E1 vs. E2.