Mechanochemistry of ibuprofen pharmaceutical

In this paper mechanochemistry has been studied in view of possible application to detoxification of expired pharmaceuticals. The experiments have been carried out with a commercial medication containing ibuprofen ((RS)-2-(4-(2-methylpropyl)phenyl)propanoic acid) which has been submitted to prolongedmilling up to 40 h. When Al(OH)3 is used as co-reagent, the first degradation step induced by the mechanochemical treatment is an acid-base reaction with the ibuprofen carboxylic acid group. The subsequent degradation follows a complex pathway leading to 1-(4-isobutylphenyl)ethanone, 1-isobutyl-4-vinylbenzeneand 2-(4-(3-methylbutan-2-yl)phenyl)propan-1-ol after 10 h milling and, in addition, 1-(4-acetylphenyl)-2- methylpropan-1-one, 1-(4-(1-hydroxy-2-methylpropyl)phenyl)ethanone and 1-(4-(2-hydroxy-2-methylpropyl) phenyl)ethanone after 40 h milling. The degradation reaction path and products have been identifiedby means of FT-IR spectroscopy, thin layer chromatography,NMRspectroscopy, mass spectroscopy and elemental analysis. The observed ibuprofen decarboxylation makes the drug simultaneously lose both its pharmaceutical activity and toxicity.