Organic Chemistry Ii Lab Report Essay

1709 Words Nov 24th, 2015 7 Pages
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Luis A. Torres
Group #11
USC Chemistry 322b
Formal Lab Report
6th November 2015
I.
II.

Enzymatic Resolution of 1-Phenylethanol and Diastereomer Analysis
Objective/Abstract
Enzymatic transesterification reaction was performed to study the resolution of
diastereomers using 1H-NMR analysis. The stereo-selectivity of acylase I, an enzyme, for
a 50:50 racemic mixture of 1-phenylethanol was determined. In the first of a two-step
reaction, 1-phenylethanol was reacted with vinyl acetate with the help of acylase I to
form an ester, unreacted 1-phenylethanol, and vinyl alcohol. The unreacted 1phenylethanol was separated from the ester by column chromatography and confirmed by
thin-layer chromatography (TLC). In the second
…show more content…
Error could be attributed to
flawed data.
Figure 1 depicts the peaks and integrations of a 50:50 racemic sample. We can see that
there is hardly any enantiomeric excess since the integrations are about the same. The
peaks at 1.5 ppm and the peaks at 1.4 ppm integrate to about a 1:1 ratio. Essentially, this
is what we expect from a racemic mixture because there should be equal amounts of the
R and S enantiomer.
Figure 2 depicts the peaks and integrations of an unreacted 1-phenylethanol sample. We
can see that the two peaks at 1.5ppm integrate to about 2.01 while the two peaks at 1.4
ppm integrate to about 0.32. This sample contains more (R)-1-phenylethanol compared to
(S)-1-phenylethanol.
Figure 3 depicts the peaks and integrations of a (R)-1-phenylethanol sample. We can see
that the two peaks at 1.5 ppm integrate to about 2.03 while the two peaks at 1.4 ppm

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integrate to about 0.54. This sample contains more (R)-1-phenylethanol compared to (S)1-phenylethanol, which is expected from this sample.
Figure 4 depicts the peaks and integrations of a (S)-1-phenylethanol sample. We can see
that the two peaks at 1.5 ppm integrate to about 1.99 while the two peaks at 1.4 ppm
integrate to about 24.04. This sample contains more (S)-1-phenylethanol compared to
(R)-1-phenylethanol, which is expected from this sample.
Figure 1: 1H-NMR of a 50:50 racemic mixture of 1-phenylethanol

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Figure 2: 1H-NMR of the…

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