Anja Johnson
21942248
Lab section: 40554
1. An SN2 reaction was conducted in this experiment using benzyl bromide and one of three
unknown
... [Show More] nucleophiles. The reaction was done in the presence of NaOH and EtOH to ensure
complete dissociation, and the NaOH was added to the nucleophile prior to the benzyl bromide.
2. The nucleophilic unknown was either 4-methoxyphenol, 4-chlorophenol, or 4-tert-butylphenol.
3. Reflux was used to ensure the substitution reaction went to completion without evaporation
occurring. Vacuum filtration allowed for the separation of solid from liquid. Recrystallization
removed impurities from the solid compound by dissolving the formerly insoluble products.
Taking the mixed melting points of the unknown solid and comparing it to the standards allowed
for a comparison between pure and impure mixtures. TLC allowed for a comparison of Rf values
of different solutions to the Rf of the unknown solution.
4. SN reactions cause a leaving group to be replaced with a nucleophile on the carbon that once had
an alkyl halide. Depending on the binding of the carbon, the strength of the leaving group, the
strength of the nucleophile, and the solvent the reaction takes place in, the substitution reaction
can either follow first (SN1) or second order kinetics (SN2); in this case, it was SN2.
5. Melting point comparisons show that when two different molecules are mixed, the melting point
of the two combined will be less than either of the two original melting points. But if two of the
same molecules are combined, the melting point should stay the same. By comparing the melting
points of the mixtures to the pure standards, it can be deduced that whichever melting point was
in the range of the standards was most likely the identity of the unknown solid.
6. Recrystallization allows for the purification of a solid compound from soluble byproducts. It is
used to ensure the properties of the solid compound are not affected by being a mixed compound. [Show Less]