The Research On Selective Aerobic Oxidation Of Cyclohexanol To Cyclohexanone Catalyzed By Metalloporphyrin

Selective oxidation of alcohols to the corresponding aldehydes or ketones is an important functional group reaction in organic synthesis, which occupies a very important position in basic research and fine chemical production. At present, the world produces over 1,000,000 tons of carbonyl compounds annually , most of which are derived from the oxidation of alcohols, traditionally, they use stoichiometric oxidants in the reaction, such as Collins reagent (CrO3·Py2), PDC, PCC, KMnO4, and other transition metaloxides and high iodine reagents.However, these methods often require equivalent or more expensive excess oxidant, and these processes are often associated with a lot of waste pollutants; Furthermore, due to the alcohols are susceptible to further oxidation of aldehydes and ketones, such as the oxidation of primary alcohols to acids. Therefore, both from an view via economic point or from the protection of the environment and sustainable development point of view, an urgent need to develop new green oxidation to replace traditional stoichiometric oxidation.In the absence of any solvents, we researched the reaction catalyzed by metalloporphyrins, which use cheap air as oxidant for the oxidation of cyclohexanol, and we also researched the reaction that use other aids composite as a cocatalyst with metalloporphyrin for the oxidation of cyclohexane, and we obtained the following conclusions:1. First, we established a new GC analysis method for the analysis of cyclohexanol, cyclohexanone, cyclohexane, we also established a new quantitative HPLC Analysis method for the analysis of monoacid, binary acid, o,m,p- cyclohexanedione, caprolactone.2. In the absence of solvents, we researched the oxidation reaction of cyclohexanol catalyzed by metalloporphyrins, we found that cyclohexanol can be oxidated under mild conditions, the main product is cyclohexanone, other products are derieved from further oxidation of cyclohexanone, cyclohexanol presence in the cyclohexanone will inhibit the conversion to ring-opening products.3. We optimized the oxidation conditions of cyclohexanol catalyzed by metalloporphyrins, the conditions is a green catalytic oxidation technology and it have not been reported so far. The optimized reaction conditions as follows: cyclohexanol: 250 g, metalloporphyrins 1 mg, temperature: 130 oC, pressure: 0.6 MPa, stirring speed: 800 rpm, air flow rate: 1.5 L/min= 0.08 m3/h. Under the same conditions using TSPPMnCl, the conversion rate of cyclohexanol is 45 % after 4 h reaction . cyclohexanone selectivity is generally maintained at about 90 %. The ring-opening products occupy only small percentage of total.4. Reference to the work of others, we researched the combined oxidation of cyclohexane catalyzed by metalloporphyrin/NHPI and found that when combined the two catalysts together, it can improve the conversion rate of cyclohexane, but NHPI can not spend too much, because it can quench the reaction when over a certain range. we also found that NHPI can shorten the reaction induction period. By a research on the decomposition of NHPI, we found NHPI have a certain stability.5. It was found through the initial mechanism research that cyclohexanol oxidation reaction is typical of radical reactions. cyclohexanol oxidation process requires the participation of oxygen. It is a catalytic oxidation reaction rather than a dehydrogenation reaction.6. By combining other additives with metalloporphyrin, we studied the synergistic effect of two catalysts, and found that methanol is better additives compared to CAN, acetic acid and cobalt oxides system response to a higher degree of cyclohexane conversion rate, but there is not a significant improvement of the selectivity of keto acid.