1.) Based on what you can find regarding the anticipated frequencies of carbonyl
ID: 915778 • Letter: 1
Question
1.) Based on what you can find regarding the anticipated frequencies of carbonyl vibrations, which carbonyl in the recrystallized product structure do you expect to have the highest frequency?
2.) How many 1H NMR peaks (ignore splitting) do you expect for 3-carbethoxycoumarin?
3.) Do you think 3-carbethoxycoumarin will absorb at longer or shorter wavelengths than benzene? Why?
4.) Compounds with an OH group usually have smaller Rf. However, salicylaldehyde is expected to have a larger Rf value than 3-carbethoxycoumarin. Why?
5.) What would happen if you reflux 3-carbethoxycoumarin with NaOH in aqueous solution?(Hint: What are the byproducts of the synthesis of 3-carbethoxycoumarin?)
H Eto OH HOAc, EtOH OEt Figure 2. The reaction you will be performing in session 1Explanation / Answer
2) C12H10O5 MOLECULAR FORMULA
The 60 MHz and 400 MHz 1H NMRs showed hydrogen peaks in all the correct positions:
60 MHz 1H NMR 1.191-2.042 (t, 3H), 4.242-4.596 (m, 2H),
7.158-7.786(m, 4H), and 8.534 (s, 1H) ppm;
400 MHz 1H NMR 1.4002-1.4358 (t, 3H), 4.3-4.4 (m,2H),
7.3310-7.3762 (m, 2H), 7.6434-7.6626 (m, 2H) and
8.5501 (s, 1H) ppm
3 )wave length 1765 cm^- it is slightly higher than the general wavelength
4) salicylaldehyde is a less polar molecule than 3-carbethoxycoumarin and has a lower Rf value
After the synthesis had proceeded for 20 minutes, TLC analysis indicated that thereaction mixture lacked any trace of salicylaldehyde (a higher spot with an Rf value is0.306
,but only contained 3-carbethoxycoumarin a lower spot with an Rf value is0.0918
Thepresence of both salicyladlehyde and 3-carbethoxycoumarina lower spot with an Rf value 0.102
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