Question

What change would you expect on the rate of theSN2 reaction of 1-iodo-2-methylbutane withcyanide ion if the nucleophile concentration isunchanged and the alkyl halide concentration isdoubled?
What change would you expect on the rate of thereaction of ethanol with 2-iodo-2-methylbutane ifthe nucleophile concentration is halved by adding diethylether as an inert solvent and the alkyl halideconcentration is unchanged?

Answer 1

Answer:

The reaction rate of the both questions remain unchanged.

Explanation:

      For question 1:  The reaction 1-iodo -2- methylbutane with cyanide ion is an SN2 reaction because the Alkyl halide is a primary alkyl halide. The rate of reaction is dependent on concentration of the nucleophile and the alkyl halide at the same. For the rate of reaction to be affected (increased or decreased), the concentration of nucleophile and the alkyl halide have to be altered.

      For question 2: The reaction of 2-iodo -2- methylbutane with ethanol is an SN1 reaction because the Alkyl halide is a tertiary alkyl halide. There are two-step reaction mechanism in this reaction. The first step is the rate determining step which determines the extent of the reaction and hence the rate of reaction. For the rate of reaction to be affected (increased or decreased), the concentration of the Alkyl halide alone will be altered. The rate of reaction is independent of the concentration of the nucleophile.