Background and overview[1]
Benzoquinone compounds are not only widely used in medical treatment, chemical industry, biological drugs, etc., but are also important organic intermediates. 2,5-Dimethyl-p-benzoquinone can be used as a pharmaceutical synthesis intermediate. If you inhale 2,5-dimethyl-p-benzoquinone, please move the patient to fresh air; if there is skin contact, take off contaminated clothing, wash the skin thoroughly with soap and water, and seek medical treatment if you feel uncomfortable; If eye contact occurs, separate eyelids, rinse with running water or saline, and seek medical attention immediately; if ingested, rinse mouth immediately, do not induce vomiting, and seek medical attention immediately.
Preparation[1-2]
The preparation of 2,5-dimethyl-p-benzoquinone is as follows:
Method 1: Add 80 grams of 2,5-dimethylphenol to 300 ml. Place dimethylformamide in 500 ml. The resin kettle oxidizer is equipped with an air inlet, a stirrer, a thermometer and a reflux condenser. 2.5 g of saladine catalyst were added and the contents were heated to a temperature of 35°C. Air was then introduced at a rate of 0.30 liters/minute. The mixer runs at 277rpm. When the oxidation device reaches a pressure of 150 psi, start venting to control the pressure. Oxidation continues until 2,6-dimethylphenol is no longer present. By quenching the reaction solution with cold water, filtering and drying, the 2,5-dimethyl-p-benzoquinone product was isolated with good purity. A yield of 99% of dimethylquinone was obtained.
Method 2: Add 0.1 mmol 2,5-dimethylphenol, trifluorotoluene, solid catalyst onion carbon, and oxidant tert-butyl hydroperoxide into a closed glass container, mix, and then ultrasonicate to form a suspension (time: 5min). Among them, 5 ml of trifluorotoluene, the molar ratio of onion carbon and 2,3,6-trimethylp-phenol is 6.66:1. The molar ratio of oxidant to 2,3,6-trimethyl-p-phenol is 3.6:1. The mixed suspension was placed in an oil bath and heated to 80°C with stirring. After 12 hours of reaction, take out the reaction vessel from the oil bath, cool to room temperature, pour out the liquid-solid mixture, and filter it to obtain the solid catalyst and the remaining liquid mixture, and isolate 2,5-dimethyl-p Benzoquinone products.
Main reference materials
[1] CN201510154630.9 A method for catalytically oxidizing phenol compounds to synthesize benzoquinone compounds
[2] US4360469 Preparation of quinones by salcomine-catalyzed oxidation of phenols
