Chemical transformations using tungsten and molybdenum hydrogen bronzes

Scope and method of study. The purpose of the study presented in this thesis was to provide an account of the chemical transformations that can be effected by tungsten and molybdenum hydrogen bronzes and the potential applications of these in synthetic and environmental chemistry. These hydrogen bronzes are simply products obtained from hydrogen insertion into tungsten and molybdenum trioxides. Reactions for this purpose were carried out in stainless steel batch reactors placed in autoclaves at various temperatures. The products obtained were sampled using gas chromatography/mass spectrometric analysis. The ability of molybdenum hydrogen bronze to selectively absorb heavy metal and actinide ions from aqueous solutions was also tested. Experiments for this purpose were performed by stirring aqueous solutions of the metal ions in a glass batch reactor at room temperature. The filtrates obtained were analyzed by a variety of analytical methods such as colorimetry, spectrophotmetry and gravimetry. The solid products were analyzed by infrared spectroscopy, thermal gravimetry analysis and powder X-ray diffraction.; Findings and conclusions. Tungsten hydrogen bronzes were found to more effective that molybdenum hydrogen bronzes in the dehalogenation of chloromethanes. Tungsten and molybdenum hydrogen bronzes also efficiently hydrated alkynes and nitriles to produce ketones and amides in high yields. The reaction of bronzes with alkenes were not so selective and produced a host of products ranging from isomerized products to coupled products. Coupled products were produced on reaction of the bronzes with benzylic mono- and polyhalides. Molybdenum hydrogen bronze was found to be highly selective for the uptake of heavy metals and actinides from aqueous solutions.