Preperation of a Diphenylacetylene

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I. Results
Started with :
40mL acetic acid4.005g PHPB
2.00g trans-stilbene1.54g KOH
13mL methanol21mL ethylene glycerol
2.726g stibene dibromide produced
Actual yield : 0.818g diphenlacetylene
Melting Point : 62 - 75 degrees Celsius

II. Discussion
The experimental melting point range of our purified product was 60 degrees Celsius when researched, but when done experimentally was only. This began around the right range, but ended up being much higher than the literature value, which means that there was some residual impurities left over from other steps. Every other reagent has a higher melting point, so it makes sense that it would be higher if the product wasn’t pure enough. They most likely contaminated the sample during the suction filtration, meaning that the crystals didn’t dry long enough. When water was supposed to be added drop – wise to make the solution cloudy, the solution was already cloudy, so the problem was evident there. Percent yield :

See attached sheet
Limiting reagent :
See attached sheet
III. Conclusion
In this experiment, we were able to see that some residual reagent left over from other steps can damage the results. The value was higher than the literature value, most likely due to contamination from previous steps. To get rid of this in the future, it is important to let crystals dry all the way after a suction filtration, in order to make sure no residual is left on them. Also, be sure to let everything dissolve completely, which might have been a problem since time was running short.

IV. Post Lab Questions
See attached sheet
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