Stoltz Lab

[moderator]

If you are working with I2, Br2, IBr, ICl, or other types of halogens in your reactions, a typical workup for this is to use sat. aq. sodium thiosulfate / sat. aq. sodium bicarbonate (1:1); the chemical formulas are Na2S2O3 : NaHCO3 (1:1). It is also possible to use sodium bisulfate as a substitute for the sodium thiosulfate.

This is also a useful technique to get rid of the precipitate formed in dess-martin periodinane oxidations (everything goes into solution afterwards).

When working on scale, it is recommended to stir with this solution as a quench until the characteristic darker color of the halogens (dark brown) disappears. Typically this is around 30 minutes. If the solution is not fully quenched, this can result in a violent explosion in the separatory funnel, especially on scale.