Sciencemadness Discussion Board - What did I synthesize?

What did I synthesize?

andresgmejiar - 4-6-2012 at 20:20

I started out by making ammonium acetylsalicylate and boiling it down to a white thick liquid. Then in another beaker I made copper(II) chloride with exces HCl and H2O2 in solution. After filtering the cuprous solution, I added it to the ammonium acetylsalicylate, which resulted in an olive green unfilterable opaque liquid. At the bottom was a pile of what seems exactly like a clump of olive green acryllic paint. Furthermore, the resulting chemical reeks of acryllic paint. Upon adding more HCl, the solution turned colorless, and the goopy percipitate turned white. I have no idea what I made, so I'm just curious if anyone has any idea.

[Edited on 5-6-2012 by andresgmejiar]

Hexavalent - 5-6-2012 at 04:39

Are you trying to tell us you mixed random chemicals in any order to see what happens? That is very irresponsible and could lead to injury.

You may have formed an insoluble complex between the copper ions and the Ammonium ASA or actually SA- under heating, the former probably hydrolyzed to give salicylic acid and ammonium acetate (the latter giving you the smell you describe). Upon adding the CuCl2 solution, copper salicylate precipitated out due to low solubility. Since acetic acid is weaker than salicylic acid, the excess HCl converts it to acetic acid, likely contributing to your 'acrylic paint' smell.. . . .I dunno, you'll have to find some solubility data or information on the colour etc. of these complexes. When you added more HCl, you may have created salicylic acid and copper chloride, as copper salicylate is slightly soluble in water.

I've personally never made this compound before (copper salicylate, although I have made copper acetylsalicylate by controlling the reaction conditions to prevent hydrolysis). In the future, though, you could probably improve your synthesis by using crystals of CuCl2...this method would eliminate and drive off any excess HCl and H2O2 I once read that it works best to neutralize acetylsalicylic acid with a salt like sodium carbonate or very dilute sodium hydroxide, but use an excess of the acetylsalicylic acid or you will, due to incorrect stoichiometry, end up with significant amounts of copper carbonate/hydroxide/oxide/other salts contaminants.

[Edited on 6-6-2012 by Hexavalent]

ManBearSwine - 5-6-2012 at 18:07

Upon strong heating, your ammonium acetylsalicylate solution hydrolyzed to salicylic acid and ammonium acetate. When you added the copper chloride solution, copper salicylate precipitated out of solution. Since acetic acid is weaker than salicylic acid, the excess HCl converts it to acetic acid, likely contributing to your "acryllic paint" smell. I've synthesized copper salicylate before, and it did precipitate out as a large, sticky mass of olive green crystals. When you added more HCl, you created salicylic acid and copper chloride, as copper salicylate is slightly soluble in water.

In the future, should you try this again, you will want to evaporate your copper chloride to drive off the excess HCl and H2O2. It works best to neutralize acetylsalicylic acid with sodium carbonate, but use an excess of aspirin or you will end up with a significant copper carbonate contaminant.

In the attached picture, the third ampoule from the left is copper acetylsalicylate, and the fifth from the right is copper salicylate.

Or maybe I'm completely wrong and you just discovered a new way to make acryllic paint.