Study On The Selective Oxidation Of O-cersol To O-hydroxybenzal Denyde Catalyzed By Co-catalysis Of Metalloporphyrin

As the main raw material of coumarin synthetic and violets preparation,o-hydroxybenzaldehyde is also an important intermediate for the synthesis of theanti-cough drug,fungicides, pesticides and so on. There are many ways of synthesiso-hydroxybenzaldehyde, while all these way have both merits and demerits.To overcome some deficiency, such as high cost of the raw material, complexoperation, harsh reaction condition, large amount of catalyst, a novel synthesis ofo-hydroxybenzaldehyde, which use o-cresol as the raw material and iron porphyrinand metal salts as catalytic agent, was developed．This new method has enormouseconomic benefits and a good prospect.In the co-catalysis system, the amount of metal salt and metal porphyrin and theratio of them was systematically studied. And reaction condition, such as reactiontime, oxygen pressure, reaction temperature stirring rate and so on, been investigatedtoo. The optimal conditions can improved the conversion rate of o-cresol, theselectivity and yield of the target product o-hydroxybenzaldehyde. By controlling thereaction conditions, we can accomplish the selective catalytic oxidation of o-cresol.The results showed that conversion of o-cresol was up to63.6%，and the maximumselectivity of o-hydroxybenzaldehyde was improved from7.7%to17.7%, under theoptimum conditions： T (p-OCH3) PPFeCl (0.37mmol/L) and Co(OAc)24H2O(0.37mmol/L) be mixed in a ratio of1:1as co-catalysis, reaction temperature is70℃,reaction time is8h, oxygen pressure is0.1MPa, stirring speed is1200r/min. Accordingto the results of the reaction, we came to the dicision that optimizing the reactionconditions was conducive to the generation of o-hydroxy benzoic acid, selectivesynthesis of o-hydroxy benzoic acid. The selectivity can reach up to99%, and theyield reached76%or even higher.After a series of experiments of changing the sorts of the metal salt and the metalporphyrin, We found several optimizing catalytic system, such as mixing cobalt metalsalt (metal copper salts) and iron porphyrinthe at the ratio of1:1, in which ratio theselectivity of reaction could reach more20%. We investigated the catalyst effect inusing different sorts of the metal salt and the metal porphyrin, and some catalystmechanisms was also been debatedFinally, the paper made a preliminary study on the oxidation mechanism of o-cresol by metal porphyrin complex catalytic system on the basis of literature and theexperiment results. It’s found that o-cresol oxidation followed the classic radicaloxidation mechanism, and the possible mechanism of o-cresol oxidation also wasproposed.