CH118K Nucleophilic Substitution

CH118K Nucleophilic Substitution - aforementioned steric...

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Michael H Tam Mht347 Substitution Reaction In this lab we not only prepare 2-chloro-2 methyl-butane, but we show it is an SN1 reaction, as well as show that the tertiary alcohol turns into an alkyl halide. Basically, we expect an SN1 reaction because the alkyl halide has to bond to the tertiary group. This is relevant because as a sp3 hybridized carbon, it is sterically difficult to bond via SN2 attacks. A couple of problems lie within this reaction. First of all, competition with elimination might occur. Thankfully, in our reaction, we can ignore the elimination reaction because the resulting compound from the side reaction undergoes an addition reaction to form the product of interest, the elusive 2-chloro- 2 methyl-butane. How do we go about proving the SN2 Reaction doesn’t take place? The answer is simple, we do a kinetics study. The preference of a substrate to undergo sn1 or sn2 depends on two effects. The
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Unformatted text preview: aforementioned steric hinderance plays a role, but the carbocation formed is also important. The more alkylhalides substituted on a carbon, the easier it is for a SN1 formation to occur. We successfully demonstrated the mechanism in lab. Our product analysis was composed of both Qualitative Analysis and IR. In the Qualitative analaysis, we would expect the sodium iodide to react faster, because its basically a halide .We also expect the halide to precipitate, proving we have a alkyl substituted bond already. The IR was successful in demonstrating the removal of the OH. There was no broad peak, and the substance given to us was pure. Therefore, somewhere along the way, the alcohol group left. It is important to note that the lab was done with miniscale * (1/2). This merely speeds up the process, the stoichiometric coeffecients never changed....
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This note was uploaded on 09/25/2011 for the course CH 118K taught by Professor Fjetland during the Spring '08 term at University of Texas at Austin.

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