Mike Marr
1/20/04
CH338
Tuesday, 8am
CH338 – Lab #1: Electrophilic Aromatic Iodination
Post-lab Report
Results
From 1.0072 grams of vanillin and 1.1766 grams of KI, my lab partner and myself
obtained 1.8403 grams of 5-iodovanillin as our crude product. After recrystallization we
obtained 0.6936 grams of 5-iodovanillin. Performing a Mel-Temp on our final product
yielded a melting point range of 178 – 181 C. During our experiment we generated a
total of 230 ml of liquid waste.
Summary
Crude product, 5-iodovanillin: 1.8403 grams, 6.612 mmol
Final product: 0.6937 grams, 2.495 mmol
MP range: 178 – 181 C
Waste
10 ml EtOH
5 ml HCl
50 ml ethyl acetate
150 ml mother liquor
Discussion
In a 100 ml flask my lab partner and I added vanillin(1.0072g, 6.618mmol), potassium
iodide(1.1766g, 7.088mmol) and ethanol(20ml). We cooled the mixture. Using a
separatory funnel we added sodium hypochlorite(11ml) over a period of 10 minutes to
our mixture. During this time we accidentally heated the mixture for approximately a
minute. No harm was done. The reaction was a creamy coffee color.
Adding sodium thiosulfate(10ml, 10%w/w) we then acidified the reaction mixture with
hydrochloric acid(~5ml, 10% w/w). During the acidification, the mixture went from the
creamy coffee color to a creamy coffee tinged with green. By the end of the acidification
the mixture reverted back to a creamy coffee color. We proceed to use a rotary evaporator
for 10 minutes to remove ethanol from the mixture.
Using vacuum filtration we removed the crystallized crude product of 5iodovanillin(1.8403g, 6.612mmol) from solution. We dried the crystals and then proceed
to recrystallize in hot ethyl acetate. After recrystallization we obtained our final product
of 5-iodovanillin(0.6937g, 2.495mmol).
We performed a Mel-Temp on our final product and obtained a melting point range of
178 – 181 C.
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Mike Marr
1/20/04
CH338
Tuesday, 8am
Conclusion
Based on the Mel-Temp results(178-181) compared to the actual melting range of 5iodovanillin(183-185) I suspect that our product was primarily 5-iodovanillin, but
contained impurities. More than likely these impurities were other mono-iodo substituted
products. Our % yield was 38%, but I believe that if we had used our mother liquor,
which contained some precipitate, to create a second crop of 5-iodovanillin that we could
have increased our yield by a fair amount.
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