Organic Synthesis. My student has been trying iodination of arenes (our goal is to iodinate p-phenylenediamine) following these literature procedures:
1. Synthesis 2004, No. 11, 1869-1873 using H2O2 / KI / H2SO4 to iodinate p-phenylenediamine
2. Org. Lett., 2015, 17(12), 2886-2889 which using NH4I / DMSO / H2SO4 to iodinate phenacetin as a model reactant similar to the dimethoxybenzenes used in this paper
In each case, we are getting a large amount of insoluble black precipitate, and NMR shows only unreacted aromatic reactant in the filtrate. The papers do not mention getting any black precipitate so Im sure its not supposed to form, I presume it must contain mostly I2 or I3- given the black colour but then why is it not soluble in chloroform or water, not sure what is going wrong? The black precipitate dissolved in DMSO but our NMR is down this week so will have to wait to next week to run it.
We emailed the authors but did not get a reply - any advice would be much appreciated!
The reaction you are attempting is usually run on a much less reactive substrate than phenylene diamine (e.g., p-nitroaniline, see the attached file). No iodination of p-phenylene diamine has been reported and the black precipitate you're getting is probably a polymer.
My advice would be to change your substrate to a less reactive derivative.
See also Chemische Berichte, 1901, vol. 34, p. 3349
- Badges
- Science topic
- Similar topics
- Chemistry