Here is a problem I encountered during the scale-up of a particular compound.
We were using 4-hydrazinobenzoic acid to open a heterocyclic ring, the structure of which is not relevant to this problem. As 4-hydrazinobenzoic acid is carcinogenic the levels of this compound in our final product were set at 0.5 - 0.1ppm or less by QC. We eventually solved it by carrying out two re-crystallisations but on the way we investigated a number of other possibilities.
One was the addition of glucose to form the osazone (compound 1 in attached file), which we could then extract out, however, we did not form the osazone but got something completely different, the structure of which still has not been determined. I suggested compound 2, the NMR spectroscopist compound 3. MS gave a M+ of 314.29 have all the NMR data etc. which I can scan in if you want to see it. We did not manage to get it crystalline for an x-ray!
Has any one here got any other ideas what this compound could be, don’t worry about the stereochemistry.