Preparation of α-tetralone by two-step catalytic method

Abstract

The invention discloses a new method for preparing α-tetralone by using tetralone as a raw material. The method is carried out in two steps: the first step is to introduce 1-20 atm (absolute pressure) air or oxygen or a mixture of oxygen and inert gas under the condition of no solvent and additives, and the reaction temperature is 60-150 °C. The monometalloporphyrin of general formula (I) or (II) and μ-oxygen double metalloporphyrin or their solid supports are used as catalysts, the catalyst concentration is 1-80ppm, and the reaction time is 1-12 hours, which can be selectively prepared Oxygenated mixture containing α-tetralin hydroperoxide and α-tetralone. In the second step, the oxidation mixed liquid obtained in the first step is used as a catalyst by a transition metal salt, and the α-tetralin hydroperoxide in the oxidized mixed liquid is selectively and directionally decomposed into α-tetralone. In the catalytic decomposition step, the molar ratio of transition metal ions to α-tetrahydronaphthalene hydroperoxide is 1:1-100, and the reaction temperature is 0-100°C. The invention has the advantages of short reaction time, mild reaction conditions, small amount of catalyst, high conversion rate, good target product selectivity, and the catalyst used is environmentally friendly and has no corrosive effect on equipment.

Description

(1) Technical field [0001] The invention relates to a method for preparing α-tetralone by a two-step catalytic method. In the first step, under the catalysis of metalloporphyrin, tetralin is selectively oxidized by air or oxygen to α-tetralin hydroperoxide and α-tetralone; in the second step, transition metal ions are used to catalyze the decomposition of the first step to produce The α-tetralin hydroperoxide, thereby highly selectively prepares α-tetralone. (2) Background technology [0002] α-tetralone is an important intermediate in the production of many medicines. At present, the industry mainly adopts the production process of using chromium salt as the main catalyst and pyridine compounds as auxiliary catalysts to catalyze the air oxidation of tetralone. This kind of process requires a large amount of main and auxiliary catalysts and high cost; moreover, the chromium salt is poisonous and difficult to separate from the product, polluting the product and the environme...

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Problems solved by technology

The consumption of main and auxiliary catalysts in this process is large and the cost is high; moreover, the chromium salt is poisonous and difficult to separate from the product, polluting the product and the environment

In addition to α-tetralone, the oxidation product of molecular oxygen oxidation tetralone also contains a large amount of α-tetralin hydroperoxide and α-tetralinol, and the selectivity of α-tetralone is not high

Wherein α-tetralinol has a great adverse effect on the subsequent use of α-tetralone, and the boiling point of α-tetralinol and α-tetralone is very close, so it is difficult to separate

U.S. Patent No. 4,175,098 has reported in DMF solvent, with chromium salt and N, N-dialkyl amides compound catalytic oxidation α-tetralin prepares the method for α-tetralone; This method will use solvent, and catalyzer is poisonous And the consumption is large, the cost is high

U.S. Patent No. 4,283,352 has reported a kind of technology that non-catalyzed oxidation prepares α-tetralone; The oxidation process of this method does not use catalyst, makes reaction time very long, and the ketone-alcohol ratio of gained product is not high

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