Showing papers in "New Journal of Chemistry in 1996"

A new environmentally benign technology and approach to bleaching kraft pulp. polyoxometalates for selective delignification and waste mineralization

Abstract: A new technology based on polyoxometalates for bleaching and processing wood pulp in conjunction with paper manufacture is presented. In four Unit Operations not only is kraft pulp selectively delignified by polyoxometalates in an anaerobic process, but also all organic waste from the bleaching step is mineralized to CO2 and H2O by polyoxometalates in a complex aerobic process. The sum of the Unit Operations is the selective conversion of kraft pulp into a bleached pulp with attractive papermaking profiles (strength indices, mechanical properties, etc.), plus CO2 and H2O. Studies using dimeric Iignin models link Iignin fragmentation during anaerobic polyoxometalate delignification to a combination of oxidative and hydrolytic steps.

X-ray diffraction and solid state NMR studies of 1,8-bis(dimethylamino)naphthalene and its complexes with picric and hexafluorophosphoric acids

Abstract: In order to get a better understanding of the nature of the N+-H...N" System characterizing the intramolecular hydrogen bond in classical proton sponges, crystal structure determinations at room temperature and at 150 K have been undertaken for the picrate and the hexafluorophosphate salts of 1,8-bis(dimethylamino)naphthalene (DMAN). Two polymorphic forms were detected br the picrate. The crystals of the orthorhombic form twinned when they were cooled. The elodgated N+-H distances, even at low temperature, are indicative of proton disorder. The polymorphism of DMAN picrate proved crucial in establishing the complementarity between the CPMAS NMR (I3C and I5N) and crystallography results.