Reduce, reuse, recycle

So you hear all the time these days that green chemistry is important. Green this, environmentally friendly that. There’s even a new term for workers at environmentally friendly companies–“green-collar.” That made me wonder what collar color (heh) chemists would get. Not exactly blue collar, but certainly not white collar…”burnt-collar workers” perhaps? Horrible brown-black nasty mess collar?

Anyway, I’m continuing my recent march through group 15 with a JOC paper from the University of Ottawa, which explores Pd-catalyzed thiocarbonylation reactions in phosphonium salt ionic liquids, or PSILs. The group had achieved thiocarbonylation in the past using certain Pd-based catalyst systems in conjunction with carbon monoxide, thiols, and aryl iodides, but they turned their attention to the reaction solvent in this paper. Using trihexyl(tetradecyl)phosphonium-PF6 as the solvent and a catalyst system of 1:4 Pd(OAc)2:PPh3, they achieved 91% coupling of PhI and PhSH. Typical yields of aryl thioesters from aryl iodides and aryl or arene-containing thiols were in the 60-70% range.

A notable feature of their reaction system was recyclability of the solvent–the product thioester could be easily separated from the ionic liquid by extraction, leaving only wet ionic liquid. After a drying step and readdition of reactants they achieved the same yield of product as they did in the first run. Hooray for green chemistry!

The paper is here.


One Comment

  1. No phys org considerations at all in the paper 😦 I may do a post on this in the near future, if the information is out there.


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