Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Mr.Gold on May 19, 2016, 07:11:01 PM
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I'm trying to essentially precipitate a carboxylic acid salt out of the solvent....the acid is fairly non polar.
If I dissolve the carboxylic acid in isopropanol and then react it with aq naoh to produce the salt....will it precipitate out of solution?
The formula is C22H304....multiple benzene rings carboxyl group ...pretty nonpolar
Or would the sodium cation association interfere with precipitation and cause it to be polar enough to stay dissolved in isopropyl?
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Well chemistry is an experimental science, try it and see what happens. You can't loose any material.
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I wish I had the luxury of time for that lol
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If you add aqueous base, there will be some water around, and I would wonder whether the sodium carboxylate salt is soluble in water. For a non polar carboxylic acid, you could try dissolving in hot organic solvent, then adding water dropwise. In other words, you could use a mixed solvent to recrystallize.
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I wish I had the luxury of time for that lol
Well instead of dicking around in the forums hoping for some answer that may not work, you could have done the experiments and found an answer.
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I wish I had the luxury of time for that lol
If there are no literature procedures for this crystallization, you are going to have to spend some time doing experiments. That's just the nature of the beast. :)
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Thx for all the input everyone! Just needed to get an idea of what kinds of solvents might work...literature is really limited and so is money...I didn't want to order a bunch of solvents to experiment with and waste my bosses money....I ended up ordering ethyl acetate...but it's on back order lol....but once again thx for all the input regardless
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One nice thing about a mixed solvent is that the overall polarity is continuously variable.
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I've had success recrystallizing a lactam by dissolving it in as little as possible in (9/1 pentane/EtOAc) while refluxing and cooling it down slowly in an oil bath (10 °C/h).
Another compound I dissolved into a small volume of EtOAc; added gradually cyclohexane until the solution became cloudy; added just enough EtOAc so the solution was transparent again; and then put it in the fridge, yielding nice crystals.
Although, in most cases when the solution cools down it turns into a cloudy solution (milk). Hate it when that happens. :(