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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N-4-phenyl picolinamide – Feb 10-Feb18 update

Image

TLC of KG04 together with reagents, phenylisocyanate, picolini acid, and diisopropylethylamine in ethylacetate/hexane eluent.

(Left, TLC in 1:9 ratio, center 2:3 ratio, right 2:3 ratio with components diluted)

The product KG04 was dissolved in acetone (not the one from the wash bottle), and TLC of of it was taken together with phenylisocyanate, picolini acid, and diisopropylethylamine in ethylacetate/hexane as eluent in the ratio of 1:9 (1.0mL ethylacetate and 9.0mL hexane). As seen in the picture (left), not much movement of the molecules were observed. Hence, new eluent for TLC was prepared with ethylacetate:hexane ratio of 1:2 (5mL and 10mL respectively). As seen in the middle of the picture, the result was better, but still not clear distinction, so another TLC was run will similar eluent, but this time the samples with diluted with acetone. The right TLC plate in the picture shows the result.

It is clear that the product does contain some picolinic acid and phenylisocyanate, but another method to analyse the product is required for detailed understanding.

Chemical dip method was done on the TLC plate, but no new spots were formed.