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| | From:  Guy_SoCa (Original Message) | Sent: 4/5/2008 4:28 AM |
For the synthesis of Dibenzalacetone (benzaldehyde + 2 moles of acetone), ethanol was used as the solvent..
what kind of complications would arise if we were to use acetone and water as the solvent..
Is it possible to say that the product would be able to dissolved and it would be hard to recrystallize it?
Thanx in advanced |
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| | | From: ·Steve· | Sent: 4/5/2008 5:00 AM |
One problem is that benzaldehyde is not very soluble in water. Other than that, water should not hinder the reaction. Water, alcohols, and water-alcohol mixtures are commonly used as solvents for aldol condensations. There needs to be some water present to keep the NaOH catalyst in solution. The product, dibenzalacetone, is insoluble in water. If the product does not readily crystallize from the alcohol solution, you can add a small amount of water to force crystallization of the product. Steve |
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Steve, I understand that Benzaldehyde is not very soluble in water.. but i believe you confused it with Acetone,  .. The question was, what kind of problems would arise if ACETONE/Water was used as the solvent instead of ethanol/water.. Acetone is miscibl in water, which would have no problem dissolving the product.. Again, thanx for your suggestions |
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| | | From: ·Steve· | Sent: 4/9/2008 6:27 AM |
Ah, yes, you're right, I overlooked the acetone. Well, if an acetone-water mixture was the solvent, I would assume that there would be a lot of excess acetone present, and you would no longer have a two-to-one molar ratio of benzaldehyde to acetone to start with. (I just noticed that the description says, "benzaldehyde + 2 moles of acetone," but it should be the other way around.) Other than that, it is true that the acetone could hinder crystallization of the product, depending on how much acetone was present. In that case, the mixture could be heated for an extra period of time to drive off the more volatile acetone. (An acetone-water mixture is great for slow crystallization of water-insoluble organic solids. Dissolve the compound in acetone, add water just to the point of causing precipitation, and then let the acetone slowly evaporate overnight by leaving the container uncovered.) Steve |
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