Iodide is a strong nucleophile but a weak base, so SN2 is the preferred reaction. Only the bromine on C1 is eligible to undergo SN2, so that one will be replaced by iodide. The product formed is 3-bromo 1-iodo 3 methylpentane Solution Iodide is a strong nucleophile but a weak base, so SN2 is the preferred reaction. Only the bromine on C1 is eligible to undergo SN2, so that one will be replaced by iodide. The product formed is 3-bromo 1-iodo 3 methylpentane.