Today I tried to make a complex of copper and hexamine by mixing a concentrated copper sulfate and hexamine sol. together. It did make a precipitate
but it look more to copper hydroxide than a copper complex. (I will test the precipitate for hydroxide in 1hour). Wath could be the reaction equation
if it is copper hydroxide that precipitated? (I'm not very good in organic chemistry.)
[Edited on 26-2-2012 by plante1999]plante1999 - 26-2-2012 at 17:09
The precipitate dissolve easily in NaHSO4 and give a blue solution. I would like to know how hexamine ionise in water.
Thanks!!ScienceSquirrel - 26-2-2012 at 19:10
I suspect that you are barking up the wrong tree.
Here is a preparation of a hexamethylenetetramine complex of copper;
[Edited on 27-2-2012 by ScienceSquirrel]plante1999 - 27-2-2012 at 17:13
So hexamine make complex with copper , but it does not explain how hexamine ionise in water, it will help me to understand the way hexamine complex
with copper. Next week I will be in the scool break week so I will do more research about this complex.
[Edited on 28-2-2012 by plante1999]Rosco Bodine - 28-2-2012 at 03:36
There is a methyl hexamine dichromate as well as a perchlorate which might be interesting. See US1336709 attached
So hexamine make complex with copper , but it does not explain how hexamine ionise in water, it will help me to understand the way hexamine complex
with copper.
In some aspects, hexamine behaves like a tertiary amine, however it is a weak base (its pKa1 is just slightly lower than for ammonia).
I doubt it is a good enough ligand for Cu(II) in order to compete with H2O, so what you obtained is unlikely to be a Cu(II) hexamine sulfate complex.
See the article provided by ScienceSquirrel for a synthesis of a related complex (they use ethanol as a solvent). You might also use some anions that
stabilize the coordination sphere instead of the sulfate. Also, coordination compounds often need some time to form and grow crystals out of the
solution (provided they are not soluble in the solvent used). Fast precipitation is not always a good sign.
Edit: Just found out that hexamine is not "just slightly lower than for ammonia", but it is almost 20 thousand times weaker (its pKa is 5.05 according
to this article). So it is practically as basic as pyridine.
