The product im getting is in dissolved form but i want it in ppt form.
Any suggestions how to get the product in ppt form.?
2,4 -Dihydroxyacetophenone can be reacted with benzaldehyde using excess of NaOH as a catalyst under aqueous conditions under stirring at room temperature for 2 to 3 hrs., then neutralize alkali with aq.HCl..
You could also heat the reaction mixture at about 80-90 dC for ~30 minutes to give the product.
Have you cooled it to zero degrees and observed an oil coming out of solution?
If yes, decant and triturate the oil with ice-cold water to obtain a solid, then filter and wash the solid with a small amount of cold water on the filter. That should be your product.
If no oil has formed, then neutralize with 6% oxalic acid solution to pH 7; filter any precipitates you get and check by NMR in D2O to see if they have organic protons; if not, the precipitate is sodium hydrogen oxalate; if there are organics, they probably correspond to sodium benzoate from oxidation of benzaldehyde, or possibly to the mono-sodium salt of your product. If the latter, dissolve in alcohol and neutralize with 6% oxalic acid solution to pH 7. Product should precipitate as pH 7 is reached.
If the solids are not product, cool the filtrate to zero and scratch the sides of the glass container to get crystals. If crystals form they are your product.
If no crystals form, then lyophilize ("freeze-dry") the filtrate to a dry powder, pack the powder into the bottom of an over-sized sintered-glass funnel and under continuous suction wash the solids with anhydrous isopropyl alcohol, grinding and packing the solid down as product dissolves. Don't use a metal spatula (metal oxide contamination can accelerate air-oxidation of your product). Don't use a paper or membrane filter in a Büchner funnel (the filter will tear). Use a ceramic spoon or spatula, or one made of hard rubber (either silicone rubber or natural rubber or synthetic rubber is fine). The lack of change in the solids (which should become nearly colorless) signals the end of washing, and the product should precipitate upon concentration of the filtrate under reduced pressure on a rotary evaporator. If not, then tarry material is present and must be removed. This can be done by decolorization using charcoal (I believe procedures are widely available) or by filtration through a short (1-inch) column of silica gel in the least polar solvent in which the product will dissolve (e.g., chloroform or toluene). The filtrate represents your best chance of obtaining crystals upon evaporation at reduced pressure. Your product will be light-sensitive and susceptible to air oxidation; protect it accordingly. Also many chalcones are sensitizers; use caution and PPE when handling the product. Best wishes with your chemistry.
Try Caisen–Schmidt condensation
under homogenous conditions in the presence of base or acid. Using EtOH and NaOH/KOH or HCl.
I think with NaOEt with cooling the reaction to zero degrees celsius.
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