Preparation of alpha-tetralone by two-step catalysis method

Abstract

The invention discloses a novel method for preparing alpha-tetralone by using tetrahydronaphthalene as a raw material. The method comprises the following two steps: a first step, under the condition without solvent and assistant, 1 to 20 atm (absolute pressure) of air or oxygen or mixed gas of oxygen and inert gases is introduced, the reaction temperature is between 60 and 150 DEG C, monometallic porphyrin of general formula (I) or (II) and mu-O-bimetallic porphyrin or solid carriers thereof are used as a catalyst, the concentration of the catalyst is 1 to 80 ppm, the reaction time is 1 to 12 hours, and oxidized mixed solution containing high alpha-tetrahydronaphthalene peroxide and alpha-tetralone can be selectively obtained; and a second step, the alpha-tetrahydronaphthalene peroxide in the oxidized mixed solution obtained in the first step is high selectively and directionally decomposed into the alpha-tetralone by using transition metal salt as a catalyst. In the step of catalytic decomposition, the molar ratio of transition metal irons to the alpha-tetrahydronaphthalene peroxide is 1:1-100, and the reaction temperature is between 0 and 100 DEG C. The method has the advantages of short reaction time, mild reaction conditions, little using amount of the catalyst, high conversion rate and good selectivity of a target product; and the used catalyst is environment-friendly and has no corrosion to 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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