PURPLE?!?!

Hmm, here’s a quick little puzzle that I’m in the middle of solving. If anyone knows the answer, feel free to let me know.

Attempting to make the acid chloride of 2-picolinic acid by SOCl2. In dichloromethane, combined ~5g of 2-picolinic acid with a slight excess of SOCl2 (~1.2:1), refluxed for ~20 minutes, removed solvent, set it aside. The initial solid was tan-brown. After a few days, it was dark. Massively dark. And green-blue, as far as the eye can tell. After a week, it’s bone dry and still massively dark. A rough yield of around 6g. So it picked up some mass…

Solubility testing… Very soluble in water, forms a deep purple solution. Soluble in methanol, solution is a bit more blue. Very slightly soluble in chloroform, purple solution. Very slightly soluble in acetonitrile, greenish leaning toward blue solution.

NMR (in D2O)… Four clean aromatic signals, consistent with the 4 protons of an ortho-substituted pyridine ring, nothing else.

20140204nmrpurple01

UV-Vis (in water)… Peak at ~540nm, shoulder at ~650nm. Strong peak at ~260nm.

20140204uvvis01 20140204uvvis02

This has not been exhaustively lit searched yet, but the intensity of the color of the product is intriguing AND a ~20% mass increase makes it a fun little puzzle. We will be exploring more…

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Characterizing N-4-phenyl picolinamide

he NMR spectrum of KG01 and KG02 were taken. The products were insoluble in CDCl3, so acetone was used as a solvent for obtaining NMR spectrum.

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ImageFrom the graphs it is clear that both, KG01 and KG02, are same product. However, clearly the products are not the ones we expected as the number of peaks are too few for N-4-phenyl picolinamide molecule. One of the possibilities is that since water was involved in the reaction (which I accidentally added in place of acetone), the N-4-phenyl picolinamide could have broken down into picolinic acid and aniline. The picolinic acid could have been washed away with water leaving aniline, so there is a probability that the spectrum is of aniline, and it does seem consistent; aniline has 4 different hydrogen environment, there are 4 major peaks with two triplet and a doublet.