I tried the bromination of isophthaldehyde with NBS in sulfuric acid. Did an extraction and evaporated the solvent, the TLC of the crude product showed 5 spots, one of which was SM, slightly above that - I thought - was my product, the rest I assumed were due to side reactions involving radicals.
So I did a column to separate the spot with the highest intensity, assuming it was 5-bromoisophthaldehyde. However, the H NMR spectrum does not add up. It shows two singlets at 10.45 and 10.40 with relative integrations 2:1. How is that possible if the compound is symmetrical? If it is not what I assume it is, and the bromination has taken place somewhere else (giving a non-symmetrical molecule), shouldn't the integrations be 1:1 (for two aldehyde protons)? The TLC of the final compound shows only one spot so I know it is pure...
Any ideas?