WHY IS IT INTERESTING TO STUDY CYCLOHEXANE OXIDATION

Cyclohexane oxidation was studied both under industrial conditions and using the Gif(IV) and the GoAgg(II) systems under ambient conditions. Under both conditions cyclohexylhydroperoxide is formed as a reaction intermediate. Using a passivated reactor and a stabilizer, cyclohexyl hydroperoxide can easily be obtained in a concentration of 7% under in dustrial conditions. Its decomposition at 80-100-degrees-C is highly s elective and the cyclohexanone:cyclohexanol ratio can be varied betwee n 4:1 and 1:3, by the use of different transition metal catalysts. Its utilization for epoxidation, however, is much more interesting. The G if(IV) system forms mainly cyclohexanone with very good turnover numbe rs but it is limited as it needs large quantities of zinc and forms co upling products with the pyridine used as a solvent. The GoAgg(II) sys tem is much more appropriate as it is homogeneous and does not form an y side products. The addition of picolinic acid strongly accelerates t he reaction and the oxidized products can be accumulated to a concentr ation similar to that obtained in the industrial process. on the other hand, the catalyst deactivates rapidly by the formation of iron (hydr )oxide particles and the turnover numbers are low. A solvent system ha s to be found which avoids the hydrolysis of the catalyst while mainta ining the high selectivity and the efficiency of the process.