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Unformatted text preview: ompetition for electron withdrawal leads to the polarity seen in the cis isomer. In the
trans isomer however, the two oxygen groups are pointing in opposite directions and the two benzene groups
are also pointing in opposite directions. This effectively cancels out the effect of different electronegative pulls
and makes the trans isomer overall non-polar. 2
Supppose your TLC analysis did not show complete conversion of trans-1,2dibenzoylethylene to cis-1,2-dibenzoylethylene. What sources of error can be used to explain
this? If your TLC analysis showed complete conversion to cis-1,2-dibenzoylethylene, what
sources of error can explain a less than 100% yield? One source of error could have come from not all of the trans compound reacting to form the cis
compound. An explanation for this could be that light did not equally shine on the solution and so some of
the trans compound was unable to form to the cis compound. Another explanation could be that the cis and
trans are similar and that it was hard to separate the two isomers using TLC analysis. TLC Qualitative/Unknown Identification
Fill in the TLC plates for the known compounds in at least two different solvent mixtures. Label
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This note was uploaded on 04/02/2014 for the course CHEM 6al taught by Professor Pettus during the Winter '08 term at UCSB.
- Winter '08