I performed the following reaction and expected the radical bromination to occur at the ethylenedioxy position (see the scheme below)
But then I obtained the brominated product at the thiophene position. WHat shall I do if I want to brominate at the ethylenedioxy positions??
The NMR spectrum are as follow,
The blue one is my starting material EDOT, and the red one is the product. It is clear that the aromatic thiophene protons are absent in the NMR spectrum
Upon vacuum solvent removal, the powder which is intially white turned to an insoluble dark blue substance. I guess it polymerized to the insoluble PEDOT (which is blue and insoluble mentioned in literatures). And this further confrmed I obtaned the brominated product at thiophene positions rather than at the ethylenedioxy positions