Discussion:
The starting materials were reacted using conditions specific to the reaction being performed and the
target product was obtained in a good yield. The reaction mixture began to boil fairly quickly. The
organic phase started collecting after about 20 minutes of the first reflux. The second reflux happened
more quickly. The third reflux was slow, and the final product yielded a relatively low amount of water
in the side-arm. The % yield of crude product was 65%. The % yield of the distilled product was 20%.
Assumptions about the procedure that were made can include that the compounds were all relatively
pure and did not contain impurities in the separation. The IR spectroscopy showed peaks at 4000, 2000,
and 1500 (1/cm). There was a large wide peak from 2800-1800. The peak around 4000 can be connected
to the IR absorption of water O-H, which is a strong, broad peak around 3700. There is no sharp peak
around 1740 to signal the presence of an ester. The large broad peak between 2800 and 1800 can not
be identified for any functional group. The IR spectroscopy showed that the ester separation was not
100% perfect and therefore, it can be assumed that the esterification of propyl propionate was not
100% successful.
There were multiple assumptions made for this experiment. To start, it was assumed that the right
amount of propanoic acid and 1-propanol was calculated and placed in the round-bottomed flask at the
beginning of the experiment. If this was wrong, the entire experiment would have been thrown off and
could have yielded completely different results. A second assumption that was made, was that there
was a complete separation of water during the three refluxes that occurred during the experiment
which would have indicated that the reaction went to completion. However, there was in fact very little
water collected in the side-arm and some of the water that was collected could have been poured back
into the round-bottomed flask during the cooling of one of the refluxes. This also could have affected
the separation and reaction. If the experiment were to be redone, the right amount of 1-propanol and
propanoic acid should be calculated properly and measured out more carefully. Furthermore, there
should be a more affective reflux method so that there can be a higher guarantee of the separation of
water. Also, a maximum time limit should be kept on the reflux so that the reaction does not change to
what is preferred.
Changes in the catalyst would not change the chemical parts of the reaction. A catalyst is an agent that
is introduced in a reaction to speed up the reaction and nothing else. It does not undergo any
permanent chemical change and merely affects the rate of the reaction without any outside influence.
This could however, produce more molecules of the final product in a shorter amount of time.
In general, by increasing the concentration of the reactants, the rate of the reaction should also
increase. Similarly, as the temperature increases, the rate of the reaction should also increase as well.
By decreasing the temperature, the rate of the reaction would slow down. Side products would be
formed. Furthermore, unstable reagents could result in a lower than expected yield. This is because
with unstable reagents, there is room for side reactions and other things to occur that are not wanted in
the end product. With unstable reagents, there are other components that can be formed or taken off
by heat or reaction which would end up with a lower than expected yield. Overall, the identity and
purity of the product was assessed.
Post-Lab Questions:
1.) On Pre-Lab Attached
2.) In this experiment, equimolar amount of carboxylic acid and alcohol are not used. There is more
propanoic acid used in a molar amount. Approximately 0.013 mol of propanoic acid was used and
approximately 0.011 mol of isopentyl alcohol was used. This would produce a higher percent yield of
ester.
3.) In esterification, the purpose of the sulfuric acid is that it is used as a catalyst for the experiment to
proceed more quickly.
4.) Most of the carboxylic acid was removed during the part of the experiment when the reaction
mixture was in the centrifuge tube.
5.) During distillation, pure product is collected when there is a temperature range plateau within a few
degrees of each other. For example, a first drop could be recorded at 55 °C during a distillation, but the
pure product may not be collected until the temperature plateau which could be something around 59-
61 °C.
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