Playing with Anthranilates
I've been introducing a lab at my college where the students do gravimetric analysis of copper using precipitation with sodium anthranilate, and it
seems to work fairly well. Of course, I've also been considering trying to grow crystals of their product (rather than just sending it for disposal),
and making some other transition metal anthranilates (as described here:
Analyst, 1936,61, 395-400
DOI: 10.1039/AN9366100395 PS- thanks again, kmno4, for the paper).
I've made some cobalt(II) anthranilate (a fleshy pink-brown), and some nickel anthranilate (a greyish-green powder, despite the paper's description of
it as green and crystalline).
Now, nickel(II) anthranilate would have four coordination sites taken by the anthranilates, but it is normally octahedral, so I figured I could put
some more ligands on it to make a different complex. It doesn't react with ammonia (surprising), and with ethylenediamine it only slowly dissolves to
give a purple solution. This is the colour of the tris(en) nickel complex, so I figure the anthranilate's no longer coordinated. Soluble in ethanol,
soluble in water, so I can't extract it from solution. Boiling it in ethanol or water doesn't change anything.
So I figure to precipitate it with isoamyl alcohol- it should be a good solvent for the excess ethylenediamine, and it's non-polar enough to encourage
the formation of a neutral complex (or just precipitate the ionic one). Adding the alcohol gives me two layers, so I figure I didn't have enough
ethanol left, and leave it overnight.
Overnight, it turns orange- not the tris ethylenediamine complex anymore. I've boiled off the excess solvent, and will try to get a solid product...
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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