I am preparing chalcone where the reactants for chalcone preparation are 2-hydroxy-benzaldehyde and 2-amino-acetophenone. Is there a way to synthesize a chalcone from these reactants?
A chalcone is a conjugated olefin and ketone, often formed by an aldol condensation. It may work with those reagents, but you have the possibility of creating a Schiff Base with the amino group and the aldehyde or ketone as well, which would be an unwanted side reaction. You may need to screen a variety of reaction conditions to get the aldol condensation to go. As it is often a base-catalyzed reaction, you may need excess base (it will deprotonate your phenol group) and have a solvent that can solubilize the sodium salt. Alternatively you may need to protect the phenol group and amino groups somehow.
you can use the classical method which work very well: To a stirred solution of 2-aminoacetophenone (1 equiv.) in EtOH at 0°C, add over 10 minutes an access of equivalent NaOH (30%) then add the benzaldehyde (1 equiv.) at room temperature, continue stirring for 24h, filter the precipitate, and purify in EtOH-H2O.
You will find the answer of your question in detail in the following newly published communication:
"Practical metal-free synthesis of chalcone derivatives via a tandem cross-dehydrogenative-coupling/elimination reaction"
Yu Wei, Jinghua Tang, Xuefeng Conga and Xiaoming Zeng
Green Chem., 2013,15, 3165-3169
follow my procedure in my article and you will get your target SYNTHESIS OF NEW FLUORINATED CHALCONE DERIVATIVE WITH ANTI-INFLAMMATORY ACTIVITY
Just protect the amino group of your 2-aminoaetophenone using acetic anhydride, and acetic acid as solvent and reflux it for 4 hrs and then isolate it by pouring ice cold water to reaction mixture....further using the crude product so obtained react it with 2-hydroxy benzaldehyde in presence of acetic acid as solvent along with catalytic amount of conc. sulfuric acid, leave the reaction mixture stirring for 2-3 days, you will surely get the success.
Yes, your preparation method is true by using ethanol as solvent, then reflux the mixture for 2-3 hr or more
For the preparation of 4-(prop-2-yn-1ylloxy) benzaldehyde, we started with 4-hydroxybenzaldhyde which was roughly 1.22g and potassium carbonate (2.57g) in 100ml of acetone which was then add to the propargyl bromide (2.67g). Then the mixture was heated under reflux argon gas for six hours and filtered and washed 3 times. The solid product was put in the heat rotation to help evaporate the solvent, then we prepared column chromatography with 75% hexane and 25% ethyl acetate as the solvent and made the silica gel made of 30-35g with the solvent. After this we ran the benzaldehyde and collected the product then places it in the heater rotation to get rid of the solvent then performed the mass-spec and IR-Spec.
For the synthesis of the chalcone we used the 4-methoxyacetophnone (0.150g) and the propargyl benzaldehyde (0.150) then mixed it with ethanol (7.5ml) in aqueous solution of sodium hydroxide (1.8g) and 3ml of water which was added dropwise for 30 minutes then left to stir for 3-4 hours at room temperature. Ice cold water was added to the combination of 5ml and then cleaned the solid produce by ethanol 2-3 times then washed it with distilled water then recrystallized by methanol: chloroform (7:3) to make the chalcone.
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