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was expected. When sec-butyl chloride was added, there was no reaction immediately but after heating, which increased the rate of the reaction, the solution turned cloudy and a white precipitate formed. This process took approximately 20 minutes. In the third test tube, t-butyl chloride was added. T-butyl chloride is a tertiary alkyl halidewhich forms a very stable tertiary carbocation during a SN1 reaction. As a result, a reaction was expected to occur quickly. When the t-butyl was added the reaction was almost immediate, producing a white precipitate.In the fourth test tube n-butyl bromide was added. N-butyl bromide is a primary alkyl halide which forms an unstable primary carbocation during SN1 reactions, so no reaction was expected; however, when n-butyl bromide was added, the solution became cloudy at
approximately 30 seconds. This was taken as an indication of a precipitate, but the test tube might also have had residue left from previous experiments that was not removed with cleaning. In the fifth test tube, allyl chloride was added. Although allyl chloride is a primary alkyl halide and would thus produce a primary carbocation in an SN1 reaction, it exhibits resonance which improves its stabilization. When allyl chloride was added a white precipitate was formed immediately. In the final test tube, chlorobenzene was added. The carbocation produced by this alkyl halide is highly unstable; therefore, no reaction was expected. When the chlorobenzene was added no reaction was observed even after heating.Part 2:In this experiment, 2 ml of 15% sodium iodide solution in acetone was placed in six test tubes. This solvent is conducive to an SN2 mechanism in which iodide acts as the nucleophile. In a SN2 reaction, the nucleophile attacks at the same time that the leaving group leaves. Evidence of this reaction is a precipitate in our experiment. If a reaction does not occur initially, the solution is heated to increase the rate of reaction. Because SN2 reactions are bimolecular and therefore dependent on the concentration of both the nucleophile and the substrate, more NaI solution is added if a reaction does not occur after heating; if there is still no evidence of a reaction it is assumed that none occurred.