NotBismuth
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Separating Phthalic Acid & Salicylic Acid
All I could find was that they're both soluble in boiling water. Would just decomposing Salicylic Acid be the feasible way? Thanks in advance 
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DraconicAcid
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Partially, it depends on the mixture. If you have mostly one contaminated with a small amount of the other, recrystallizing it a few times from water
may be sufficient. If it's more of a 50:50 mix, then it will be more challenging. Chromatography might work. You might find that their sodium or
potassium salts have sufficiently different solubilities in alcohol or acetone to separate the two.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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NotBismuth
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Well the Phthalic Acid would be the dominant - the Salicylic Acid is formed from the Ester Hydrolysis of a Sodium Salicylate catalyst. Thanks! :]
[Edited on 29-5-2019 by NotBismuth]
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TGSpecialist1
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Calcium phtalate is insoluble.
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DraconicAcid
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Calcium salicylate has a solubility of 2.3 g/100 mL. That should be enough to remove a small amount of salicylic acid.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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TGSpecialist1
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You could first convert the acids to sodium salts then add just enough CaCl2 to selectively precipitate calcium phtalate.
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DraconicAcid
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This book: https://books.google.ca/books?id=KPyLb5f-p4EC&pg=PA224&a...
says that both calcium phthalate and calcium salicylate are insoluble.
Some other possibilities.....
Zinc salicylate is very soluble, zinc phthalate is not (according to the above book).
To precipitate calcium phthalate, you need to remove both the hydrogens from phthalic acid; to precipitate calcium salicylate, you only need to remove
one. if you kept the pH at 4, you'd convert all the salicylic acid into salicylate, but all the phthalic acid would be the hydrogen phthalate ion
(which might not precipitate with calcium- you'd need to find the Ksp values for the compound to determine it theoretically).
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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TGSpecialist1
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Phthalic acid pKas = 2.89; 5.51
Salicylic acid pKas = 3.0; 13.4
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DraconicAcid
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Yes, so if you adjust the pH to about 4, you'll take one H+ off of both acids. However, for the purposes of precipitating out any salts, the second
hydrogen on salicylic acid can be ignored, and we can treat it as a monoprotic acid.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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fusso
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What?! These Chemicals are allowed in Singapore?!
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NotBismuth
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Just need to source Diethyl Phthalate solvent from Glowsticks and hydrolyse it to Phthalic Acid. Seeing that this is just a proof of concept &
efficiency isn't a priority, it would make more sense to proceed VIA the acid catalysed approach. HCl can either be obtained through distillation of
toilet cleaner or from the reaction of Sulfuric Acid & Salt. Sulfuric Acid can easily be obtained from Car Battery or just burning Sulfur and
bubbling the Dioxide into Hydrogen Peroxide :¶
P.S. I'm using Glowsticks as the source because I'd also need the Phenol from it - probably to make Phenolphthalein
[Edited on 3-6-2019 by NotBismuth]
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