I have a really old sample of sodium tetraphenylborate. It should be white, but it is red. Does anyone know what was formed and how it influences precipitation of cations in water?

  • $\begingroup$ Hm. How was the sample stored? It might give us an idea of what was reacting with it. $\endgroup$ – Breaking Bioinformatics Jun 5 '15 at 12:24
  • $\begingroup$ Yes, more details would be useful. $\endgroup$ – Mithoron Jun 8 '15 at 11:43
  • $\begingroup$ @BreakingBioinformatics because it was stored about ~30 years in closed bootle, water, oxygen and carbon dioxide could somehow get in. Tetraphenylborate ion does not looks stable in acidic medium, so oxidation of boron atom may begin. These are only my thoughts about what is going on here. $\endgroup$ – BalticMusicFan Jun 8 '15 at 15:43
  • $\begingroup$ Haven't found information about tetraphenylborate ion and triphenylborane oxidation products named boroxines. These could be precipitated out of tetraphenylborate ion containing solution with aluminium ion containing solution (aluminium(III) chloride) most likely due to its attraction to oxygen. Feel free to research ;) $\endgroup$ – BalticMusicFan Jun 8 '15 at 16:01
  • $\begingroup$ Was the bottle glass, plastic, or metal? $\endgroup$ – Breaking Bioinformatics Jun 8 '15 at 16:04

According to Decomposition of Sodium Tetraphenylborate, which relates to the Savanna River site for nuclear weapons material production,

Stable aqueous NaTPB solutions are a transparent, flesh-toned color. During the initial stages of decomposition (or instability),the solution turns a golden color. As the quantity of TPB- that has decomposed increases, the solution turns dark red, then brown, and eventually black.

In the presence of oxygen "phenol and phenylboronic acid are produced as well as benzene, biphenyl, and other benzene ring derivatives".

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