Conversion of Alcohol to Alkyl Halides Essay

2563 Words Aug 12th, 2013 11 Pages
Conversion of Alcohols to Alkyl Halides
Ankita Patel
August 6, 2013

Introduction This lab consisted of the conversion of alcohols into alkyl halides through common substitution methods. These methods include SN1 and SN2 mechanism, both of which can occur for this type of reaction. For both reactions, the first step of protonation will be to add hydrogen to the –OH group and then the rest of the reaction will proceed according to the type of mechanism. SN1 reactions form a cation intermediate once the H2O group leaves, then allowing a halide (such as Br) to attack the positively charged reagent1. On the other hand, SN2 reactions are one-step mechanism in which no intermediate is formed and the halide attaches as the leaving
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Thus, one could safely assume the product from 1-propanol was 1-bromopropane. This is mainly due the C-H wag around 1260cm-1 indication it was a terminal alkyl halide. This reaction went through SN2 mechanism not only because the alcohol was primary but also because there were no rearrangements. If a rearrangement would have occurred, it would have indicated that it was a SN1 mechanism. Further analysis was then done to determine the exact identity of the product and the chemical makeup.
B
B
C
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B
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Figure 2: NMR Spectrum for 1-propanol
The results from the NMR of 1-propanol showed 3 different prominent peaks with the peak at 2.2 cm-1 being the acetone. Because 1-bromopropane has three non-equivalent hydrogens it was found to represent this set of NMR data. The other product, 2-bromopropane only had 2 different types of hydrogens and would have only had 2 peaks. Further analysis of the structure of 1-bromopropane showed that the hydrogens closest the bromine group were an indication of peak A in the graph. Because of the electronegativity of the bromine, this peak was located further downfield. There were 2 neighboring hydrogens so using the n+1 rule gave the 3 peaks. Going down peak B showed the next carbon which had 5 neighboring hydrogens thus giving 6 peaks. Finally, the carbon furthest away from the bromine was found at peak C. It had 2 neighboring hydrogens and provided 3 peaks.
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