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A solvent for selenium

A solvent for selenium
11 May 2014 - Nanotech

A solvent for selenium.PNGAs reported earlier Webber et al. have recently demonstrated that a mixture of a thiol and an amine can dissolve an impressive amount of tellurium. That was not all that there was to it. The same mixture also works for selenium. For example a 1:4 mixture by volume of ethanethiol and ethylenediamine can be 38% in Se. With regards to a mechanism Webber noted that conductivity increased during dissolution (ions!), that the thiol was deprotonated (proton NMR) and that selenium ring structures were formed (Raman).

But this is not all there is to it. Another research group appears to make the same thiol-amine-selenium claim. In an accepted manuscript Walker and Agrawal ( DOI) demonstrate that a very similar 2:1 mixture of ethanethiol and oleylamine can dissolve up to 5% selenium. Both teams report that solubility in either solvent is negligible. In the Walker mechanistic scheme the thiol is oxidized to a disulfide (spotted by GCMS). Selenium is reduced to the Se82- anion. The solution has to be basic and that explains the amine. The ammonium ion and the Se82- anion combine to form the dark-red solution. Webber does not mention disulfides.

So who can claim priority? Both teams cite Liu et al. (DOI) who in 2012 used hexadecanethiol, oleylamine and selenium and already described it as a alkylthiol reduction. In 2014 the Webber article is older by three weeks but Walker & Agrawal have not been in a hurry: they confidently write their solution is stable for up to three years.