Experiment 4: Kinetics of Nucleophilic Substitutions
1. Determine the effect of varying [OH-] on the rate of the reaction. To do this, you should complete the following table: Experiment [tBuCl]0 (M) [OH-]0 (M) Time (s) Reaction rate (M/s) Rate constant (s-1)
1 0.03 0.003 65 4.89 · 10-5 1.62 · 10-3
2 0.03 0.006 213 3.15 · 10-5 1.05 · 10-3
3 0.03 0.009 362 2.96 · 10-5 9.85 · 10-4 What is the dependence of [OH-] on the rate law?
The effect of the increased or decreased [OH-] on the rate law is very minimal. As the concentration of OH- is increasing, the rate of reaction is increasing at a very low rate. This is a plausible conclusion because a reaction involving a tertiary alkyl halide will follow SN1 mechanism. …show more content…
The effect of the increase or decrease of [tBuCl] is evident by observing the reaction rate for each trial. As the initial concentration of tBuCl is increasing, the rate of the reaction is also increasing. As explained above, since this is a SN1 mechanism, the reaction rate is only dependant of the increase or decrease of the tertiary alkyl halide, Hence, the rate law for this reaction will be Rate = k [tBuCl], where the change in concentration of OH- will play no role other than being a nucleophile in the reaction. 3. Based on the experimental rate law, what substitution mechanism(s) do you think are happening in the solvolysis reaction of tBuCl? What substitution product(s) do you predict for this reaction (draw the reaction mechanisms and product structures)?
The substitution mechanism that is happening in the solvolysis reaction of tBuCl is the SN1 mechanism, where only one type of molecule will affect the reaction rate. The data is the tables above is indicative of this conclusion, because the change in [tBuCl] has an effect on the reaction rate while the [OH-] does not have an effect on the reaction rate. This the reaction involves a tertiary alkyl halide, which is tert-butyl chloride, which further indicates that the reaction follows a SN1
1. Determine the effect of varying [OH-] on the rate of the reaction. To do this, you should complete the following table: Experiment [tBuCl]0 (M) [OH-]0 (M) Time (s) Reaction rate (M/s) Rate constant (s-1)
1 0.03 0.003 65 4.89 · 10-5 1.62 · 10-3
2 0.03 0.006 213 3.15 · 10-5 1.05 · 10-3
3 0.03 0.009 362 2.96 · 10-5 9.85 · 10-4 What is the dependence of [OH-] on the rate law?
The effect of the increased or decreased [OH-] on the rate law is very minimal. As the concentration of OH- is increasing, the rate of reaction is increasing at a very low rate. This is a plausible conclusion because a reaction involving a tertiary alkyl halide will follow SN1 mechanism. …show more content…
The effect of the increase or decrease of [tBuCl] is evident by observing the reaction rate for each trial. As the initial concentration of tBuCl is increasing, the rate of the reaction is also increasing. As explained above, since this is a SN1 mechanism, the reaction rate is only dependant of the increase or decrease of the tertiary alkyl halide, Hence, the rate law for this reaction will be Rate = k [tBuCl], where the change in concentration of OH- will play no role other than being a nucleophile in the reaction. 3. Based on the experimental rate law, what substitution mechanism(s) do you think are happening in the solvolysis reaction of tBuCl? What substitution product(s) do you predict for this reaction (draw the reaction mechanisms and product structures)?
The substitution mechanism that is happening in the solvolysis reaction of tBuCl is the SN1 mechanism, where only one type of molecule will affect the reaction rate. The data is the tables above is indicative of this conclusion, because the change in [tBuCl] has an effect on the reaction rate while the [OH-] does not have an effect on the reaction rate. This the reaction involves a tertiary alkyl halide, which is tert-butyl chloride, which further indicates that the reaction follows a SN1