# Reactivity of primary and tertiary alkyl halides

From USNCO 2004, Q58:

The reaction between which pair of reactants occurs the fastest for $$[\ce{OH-}] = \pu{0.010 M}$$?

(A) $$\ce{CH3CH2CH2CH2Cl + OH-}$$

(B) $$\ce{(CH3)3CCl + OH-}$$

(C) $$\ce{CH3CH2CH2CH2Br + OH-}$$

(D) $$\ce{(CH3)3CBr + OH-}$$

The following is my thought process:

• This reaction occurs through one of the SN2, SN1, E1 or E2 pathways.
• All pathways prefer better leaving groups. $$\ce{Br-}$$ is a better leaving group than $$\ce{Cl-}$$, hence (A) and (B) can be eliminated.
• The nucleophile is strongly basic, so will favor E1 and E2 reactions.

However, I am unable to choose between E1 and E2, and option (D) or option (C), respectively.

Also, if there is any error in my reasoning, could it be pointed out?