One cannot help but to appreciate one's first love, and my first scientific love was synthetic organic chemistry, which is a very beautiful science - one that generates a great sense of aestheticism besides scientific rigor. (I will curse loudly if someone tells me that "organic chemistry is all memory" by the way.)
Unfortunately these are bad times in this country for organic chemistry and the science, like most sciences here, is culturally undervalued. It's different elsewhere. Recently I heard some Chinese business people complain vociferously that things are rough in China, because the salaries of organic chemists in that country are rising on average about 25% per year.
We should suffer so much.
In more recent years I have been studying nuclear chemistry in all my spare time, and so first and last loves in mind, I was very pleased to read a really wonderful paper written in the Journal of Chemical Engineering and Data, a publication of the American Chemical Society, about the organic synthesis of a new highly selective agent for the extraction of the valuable metal palladium from used nuclear fuel, a paper (predictably) written by Chinese chemists.
The paper from the primary scientific literature I will discuss tonight is J. Chem. Eng. Data, 2012, 57 (4), pp 1267–1273 and is entitled "New Insight into the Partitioning of Minor Actinides I: Extraction of Palladium and Some Typical Metals with a Multidentate Soft-Ligand 2,6-Bis(5,6-dinonyl-1,2,4-triazine-3-yl)pyridine."
I have written in this space before about palladium, most recently in connection with some environmental issues connected with its use in cars: Tracking Aerosol Palladium From Catalytic Converters In the Atmosphere.
I have also written about the presence (and value) of palladium, a fission product, (in connection with another even more valuable metal) in used nuclear fuel:
Supply of Rhodium in Used Nuclear Fuel To Exceed World Supply From Ores by 2030.
In the paper above, an organic extractant for use in PUREX type chemistry - for the isolation of plutonium from used nuclear fuel - is synthesized and used.
PUREX chemistry - which is a solvent extraction process used on nuclear fuels that have been dissolved in nitric acid - is the chief industrial method used for the extraction of plutonium from used nuclear fuel. I'm not exactly a fan of PUREX chemistry, but there are no PUREX facilities on earth that have proved quite as dangerous as your ordinary oil refinery, not that anyone gives a rat's ass about oil refineries. While I might favor other types of chemistry for the reprocessing of used nuclear fuels, I have no objection to improvements in the existing industrial process, and this is a nice one.
Some organic chemistry talk: The ligand for the extraction of palladium from used nuclear fuel is synthesized from 2,6 dicyanopyridine which is reacted with hydrazine to give the corresponding pyridine-2,6-diamidohydrazone. Meanwhile the sodium ethyl enolate of caproic acid (which can be isolated from things like palm oil) and other vegatable oils - the ethyl ester starting material is a constituent of biodiesel - undergoes copper (II) catalyzed coupling to give 10, 11 eiscosane dione, which is then coupled under relatively mild conditions to give the title compound above.
The overall yield is not given in this paper, but a reference a master's thesis at Zhejiang University is given.
The compound is thereafter referred to as nonBTP, where the non is not a negation but refers to the four nonyl moieties contained the molecules.
The paper claims some remarkable selectivity for the extraction of palladium from the PUREX raffinates:
With an increase in contact time, the extraction of Pd(II) with NonBTP increased quickly at initial 30 min and then kept constant, reflecting that it reached the extraction equilibrium. The distribution ratio (D) of Pd(II) in excess of 30 min was always greater than 765, while the tested metals Ru(III), Fe(III), Zr(IV), Co(II), Ni(II), and Mo(VI) showed weak or almost no extraction with NonBTP. The distribution ratios (D) of them at contact time of 90 min were always less than 0.1553. Such a low value in the distribution ratio resulted from the weak complexation of these metals with a nitrogen atom inside the NonBTP molecule.
It is possible - with quick isolation of ruthenium from hot nuclear fuels followed by allowing the radioactive ruthenium-106 to decay with a half-life of slightly more than a year - to obtain isotopically pure non-radioactive palladium-106.
However palladium isolated from aged nuclear fuels will always contain small amounts of the weakly radioactive Pd-107 isotope as well as the stable non-radioactive isotopes of palladium. The radioactivity would however not preclude the use of the isolated metal as a catalyst in closed systems, nor would it preclude the use of said palladium in the preparation of highly specialized "superalloys" that might be used in refractory systems, especially high temperature nuclear systems.
By the way, this paper barely mentions the minor actinides, americium and curium, to which the title refers, but it is published as the first of an intended series.
It's a little bit esoteric, but I really enjoyed this paper that brings together two of my favorite sciences, nuclear science and organic chemistry. Kind of cool I think.
Well, I guess you had to be there.
Have a nice evening.