Chloroform chemical storage

18 June 2012 - Orgo

A new use for chloroform? We know it as a solvent, as a precursor to teflon and perhaps as precursor to dichlorocarbene. In Organic Letters Yuki Kuwahara and colleagues add a new use: that of cheap chemical storage vehicle for elemental chlorine, HCl and phosgene. DOI. How? Expose to oxygen and ultraviolet light. The photochemical decomposition of chloroform is complex but you end up first with HCl, Cl2 and ClCOCl and finally with carbon dioxide and carbon monoxide as well. Of course phosgene is very toxic and safe storage will always be an issue.
The photochemically enriched chloroform was successfully tested on several substrates (anisole, anthracene) in simple chlorination and then with phenol in esterfication to diphenylcarbonate. The last reaction did require an excess of triethylamine needed to remove the HCl.