Knoevenagel condensation to make a coumarin - laboratory experiment

[@ChemHelpASAP]

If you do want to purify the product, the original reference mentions recrystallization from ethanol.

[@pascalhumbert97]

First step of the hantzch pyridine synthesis, needed this for revision for my heterocycle synthesis exam on friday, thanks!

[@ChemHelpASAP]

All those condensation routes to heterocycles are beautiful reactions.

[@TheSiliconchip]

Thanks a lot. I was able to prepare it.

[@conceptdctorz7006]

Respected sir, I had tried to prepare this compound by using the solvent method (ethanol) I recrystallised it and watched tlc it was 3.4 cm in 6 cm reference. After 10 days I watched tlc again and now I am getting one small black spot above the spot of my product. I kept it in a seal packed voil. Please help me what to do?? I want to follow your method but I am not allowed to do it in this much quantity I am allowed to do test reaction first so how much amount can I take ???? Please reply me

[@ChemHelpASAP]

Is the TLC reproducible? Have you seen the black spot multiple times? Has the appearance of the product changed? If you are seeing a black spot, I would expect obvious darkening of the product. If the product looks the same in the vial, then I would not worry. How is your melting point (if you have one)? If you recrystallized the product, then I'd expect the appearance and mp to be quite nice. I don't know how to advise you on the reaction scale. Can you do 10 mmol instead of 50 mmol? You can proportionately scale all the reagents.

[@conceptdctorz7006]

​@@ChemHelpASAP sir, there is no change in colour and appearance. I checked the melting point it was near about 118 degrees Celsius. I can send you photo of my tlc but where to send?

[@ChemHelpASAP]

@@conceptdctorz7006 Have you run the TLC again to confirm? TLC plates can often have stray spots on them under UV. The product should be stable. Do you have any data other than TLC to confirm the identity of your product?

[@svtopare]

Which solvent have you used to dissolve the 3 acetyl coumarin product for taking its TLC?

[@TheSiliconchip]

Thanks a lot.

[@miladarbabi1564]

thanks

[@TheSiliconchip]

I am stuck in making its chalcone with 4 OH or 4 Me benzaldehyde now. Not getting any product with KOH 1mM or Piperidine or morpholine. with KOH the solution of 3 acetyl Coumarine turns red and no reaction. tried reflux for 2 to 8 hours. Where is the mistake?

[@ChemHelpASAP]

3-acetyl coumarin is going to be a very good Michael acceptor. You might have some side chemistries occurring that are reducing product formation and preventing precipitation. There is a lot of more functionality in the coumarin than a typical acetophenone.

[@TheSiliconchip]

What procedure will you suggest for this synthesis so that I may try that. Any paper or your solution for this. Thanks

[@pramsakpatawanich8750]

@@TheSiliconchip it depends on many factors, for example, what the solvent you used, how much base you added

[@conceptdctorz7006]

Respected sir, I had tried to prepare this compound by using the solvent method (ethanol) I recrystallised it and watched tlc it was 3.4 cm in 6 cm reference. After 10 days I watched tlc again and now I am getting one small black spot above the spot of my product. I kept it in a seal packed voil. Please help me what to do?? I want to follow your method but I am not allowed to do it in this much quantity I am allowed to do test reaction first so how much amount can I take ???? Please reply me