Nucleophilic+Substitution+Reactions

= Nucleophilic Substitution Reactions =

**__Introduction:__**
The purpose of this lab is to analyze the effects of the solvent on the rate of a SN1 reaction. The solvents that were used were a polar aprotic solvent (Acetone) and a polar protic solvent (Isopropanol). Acid is added to a solution of alkyl halide and a color indicator which changes color when the reaction finishes. only in one flask, a positive control.  Using the time it takes for the reaction to finish, the data will be analyzed to find out which solvent is better for this reaction. A polar protic solvent is a solvent which have an H directly bonded to an O, N, or X (Halogen). A polar aprotic solvent is a solvent which does not have an H directly bonded to a O, N, or X.

 Thank you for including the reaction in your introduction.

__Procedure:__
From: CH242/338 Organic Chemistry II Laboratory: Nucleophilic Substitution Reactions. Given by Carol Higginbotham.

__Data__:
I copied your work from here and put it in so it wouldn't be in a link for it? .
 * In the chart above, some numbers are recorded to the second digit? as advised by the lab procedure**



__Conclusion:__
This experiment was meant to illustrate the differences that occur in reaction times for an SN1 depending on the solvent that is used. The alkyl halide was 2-chloro-2-methyl propane and the two solvents tested for this lab were acetone and isopropanol. According to the data from the five groups, the acetone solvent reacted quicker than the isopropanol. This result seems surprising, as it was predicted that the reaction involving the isopropanol would react more quickly than the reaction containing acetone. This prediction was made because isopropanol is a polar protic solvent, whereas acetone is a polar aprotic solvent. For an SN1 reaction, the polar protic solvent should be favored, therefore reacting more quickly. This is could be due to the limited amount of trials completed for this lab. Data from all experiment groups followed the same general trend, showing a direct correlation between the amount of water included in a mixture and the quickness with which the reaction completed.

Consider this: the degree of polarity of a solvent (acetone vs. the alcohol) varies. So it turns out that while acetone is not protic, it is far more polar than the alcohol and therefore speeds the reaction. Now, how does the proportion of either solvent (acetone or alcohol) vs. water affect the rate? You haven't discussed that, here, and there is an interesting and clear trend in the data.

__Possible Errors:__
1) Test tubes used were used by a previous class and were not completely dried. The substance remaining was assumed water but may have not been. did you clean them out? That would have made this issue go away. 2) In flask number two there may not have been enough reagents for the reaction to completely react which created the indicator to not become completely yellow.

Post Lab Q1:
Suggest 3 other solvents that might be effective for completing the SN1 reaction we performed. all reasonable choices.
 * Ethanol, Methanol, Acetic Acid**

Post Lab Q2:
Suggest a different alkyl halide that might be used if we wanted to get evidence (from polarimetry) that our reaction actually proceeds by SN1, rather than SN2. -Another substance which creates a tertiary carbocation such as //3-chloro-3-methyl-pentane//; as long as the alkyl halide creates too much steric hindrance to proceed via SN2 reaction and no heat is involved, the reaction theoretical should proceed via SN1. Whoops, this one wouldn't work! It does not have a chiral carbon so you wouldn't be able to see the stereochemical consequences of the reaction. Also, you can do SN1 reactions with secondary alkyl halides.

This report earned the following scores for: format (2/2) style (2/2 but watch for typos!) data (3/3) quality of result (1/1) quality of reported data (1/1) conclusion (1/2) error (0.5/1) post-lab questions (1.5/2) for a total of 12/14. This is a solid report; well done.