ORGANIC-WATER INTERFACIAL SYNTHESIS OF ALPHA-TETRALONE USING NICKEL-TETRAETHYLENEPENTAMINE COMPLEX CATALYSTS

Biphasic autoxidation of tetralin to alpha-tetralone has been carried out using surface-active ligand complexes of nickel as catalysts, tetr alin as the substrate and organic phase, and dodecyl sodium sulfate as an emulsifier. The major products formed under the mild reaction cond itions of 60 degrees C acid 1 atm were alpha-tetralone and alpha-tetra lol, and the highest selectivity of 71% to the preferred product alpha -tetralone was obtained with nickel-tetraethylenepentamine complex, De pending on the ligand used, ligand to catalyst ratio of 2:1 or 1:1 was optimum accelerating the reaction rate and phase separation. The orga nic-water phase volume ratio around which the maximum reaction rate wa s obtained varied somewhat with the ligand used in the reaction, but g enerally 1 : 1 or 2:1 was adequate, The reaction order with respect to oxygen shifted from first to zero as its partial pressure increased a nd the reaction order with respect to nickel catalyst concentration va ried from 1.7 to 1, and subsequently to 0 with further increases in th e metal concentration. A kinetic model based on a free radical mechani sm is proposed which yields a rate law in accord with the experimental findings. (C) 1998 Academic Press.