some times ago swim was tried to demethylation of vanillin using pyridine and AlCl3. After 18 hours of reflux he get dark red mixture, and after extraction with Et2O he get yellow crystals with vanillin smell (it smell like veratraldehyde, i love it!). I think that he used not-dry pyridine and something was wrong.
i dont know why i writing this post (maybe someone have simmilar experience?).