In a part of my research, I am synthesizing a chalcone from 2-4-dihydroxy acetophenone and various benzaldehyde derivatives. I am following your procedure published in article but I could not get the success in the reactions so please help me.
Hi, I noticed that you do not specify the reactive agents you are using. If you are working in a basic medium take in account that your acetophenone reactant has two phenol groups which are acidic. Maybe that is what’s troubling you
You are using 2, 4 dihydroxy acetophenone and other benzaldehyde in basic condition (NaOH in Methanol), Try to reduce the volume after preperation of Chalcone and keep in refrigerator for overnight, Chalcone must precipitate. Becoz, dihydroxy chalcone are highly soluble in methanol/ water mixture.
I don't kow your reaction conditions. In my opinion basic conditions are not a good choice, because the phenolic groups are probably converted into the corresponding phenoxy groups and this could dramatically reduce the basic character of the protons in alfa position to the cabonyl group.
We have prepared some chalcone related compounds using ammonium acetate/acetic acid mixtures. Try to use the following proportions: chalcone (0.66 mmol), aldehyde (0.66 mmol), NH4OAc (1.46 mmol) and AcOH (6 mL).
Acid catalysis is the way to go! Any strong acid should work (1-2 mol%). No solvent is needed if you're using at least one liquid reactant, stirring at 100-120 C, no special atmosphere are drying required. Cool down for precipitation of the product.
you may need to acidify with 20% HCl after pouring in water since you have to acidic OH
First try to protect the hydroxyl group with DMS or Benzoyl Chloride or other protecting group (information you will get from literature). Then carry out the reaction of protected dihydroxyacetophenone with suitable aromatic aldehyde. Protection is must since phenolic hydroxyl group are much reactive.
Using thionyl chloride in ethanol as a catalyst will avoid any problems in the chalcone synthesis as hydroxyl group which not need to protection
follow my procedure in my article and you will get your target
SYNTHESIS OF NEW FLUORINATED CHALCONE DERIVATIVE WITH ANTI-INFLAMMATORY ACTIVITY
See this article:
Rajender S. Varma, Manju Varma,
Monatshefte für Chemie / Chemical Monthly
December 1982, Volume 113, Issue 12, pp 1469-1473
React 2,4-dihydroxy acetophenone with benzaldehyde in presence of NaoH stirr the reaction mix. with cooling, the chalcone separates out .
Please kindly read the following article to find the solution of your problem:
Analele Universităţii din Bucuresti – Chimie (serie nouă), vol 20 no. 1, pag. 15 – 24
K.L. Ameta , Nitu S. Rathore and Biresh Kumar
Good luck.
you have to try in Ethanol as a solvent and AcOH catalyst (excess) for 24 hours you will get nearly 40-50% yield
working with 2'-hydroxyacetophenones with additional OH group is very complicated. I get polyoxygenated chalcones only using MOM as protecting group. CAUTION with MOMCl because is very toxic. I recommend the following articles:
Protection:
1. Han, J.H.; Kwon, Y.E.; Sohn, J.-H.; Ryu, D.H. A facile method for the rapid and selective deprotection of methoxymethyl (MOM) ethers. Tetrahedron 2010, 66, 1673–1677.
Chalcone synthesis:
2. Lin, A.-S.; Nakagawa-Goto, K.; Chang, F.-R.; Yu, D.; Morris-Natschke, S. L.; Wu, C.-C.; Chen, S.-L.; Wu, Y.-C.; Lee, K.-H. First Total Synthesis of Protoapigenone and Its Analogues as Potent Cytotoxic Agents. J. Med. Chem. 2007, 50, 3921-3927.
Deprotection of MOM groups is easily obtained by hydrolysis in HCl 1N/MeOH
Luck.
First protecting OH group present in acetophenone an benzaldehyde with MOMCl (DIPEA), then synthesize chalcone in alkalyne conditions (KOH/MeOH). Finally hydrolize MOM group un acid condition. See the articles send before.
In this case is better use acid conditions as tionylchloride in methanol!
I also have the same problem,
I used ethanol and KOH for 2,4 dihydroxyactophenone and DMAB but the product is not convincing enough as it only shows few precipitate.
(ongoing research)
any other suggestion?
Dear Researcher
I am also trying to prepare Schiff bases from 2,4-dihydroxy benzaldehyde with various groups. Although I have succeed, I found a difficulty to isolate the Schiff base because of very high solubility of the product. I thick, after TLC confirmation you should reduce volume and then cooling in refrigerator.
We carried out similar type of experiment in presence of NaoH followed by stirring the reaction mixer. After cooling, the chalcone separates out.
Since you have OH groups,you may need to add some acid to isolate the product.
Please kindly read the following answer of Hassan Fawzy Madkour
If the compound have the hydroxy group, it will form phenoxide, so you will get less yield. It is better to protect the hydroxy group
i have same problem.i need synthesis of chalcone from substitute benzaldehyde and acetophenone in acide or base medium but chalcone isnt form.so i need help please!!!!!
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