Preparation method of propofol and structural analogues of propofol
A compound, isopropyl technology, applied in the field of preparation of propofol and its structural analogs, can solve the problems of dangerous hydrogenation conditions, acid corrosion, complicated reaction operation and the like
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preparation example Construction
[0071] The preparation method of solid acid described below comprises: 90% (volume fraction) vitriol oil and 20% (volume fraction) phosphoric acid are mixed by volume ratio 5:1 and mixed acid is made; 120 mesh gacs are mixed with above-mentioned mixed acid by weight 10: 1. Mix evenly, soak for 10 hours and put it into muffle furnace for carbonization for 2 hours. The carbonization temperature is 450-500°C. The obtained solid is sulfonated with 98% (volume fraction) concentrated sulfuric acid for 8 hours, and dried until the water content is less than 10%, to obtain the solid acid catalyst.
[0072] The distillation method described below includes: first use a Roots pump to distill low-boiling substances at a temperature of 50-60°C and a vacuum of -0.05-0.09MPa, then rectify with a packed column at a vacuum of 1-100Pa and the rectification temperature For 110 ~ 140 ° C, collect the corresponding fractions.
Embodiment 1
[0073] Example 1 Preparation of 2,6-dimethylphenol
[0074] (1) In a 500ml reaction flask, add 138g (1mol) of p-hydroxybenzoic acid, 160g (5mol) of methanol, and 50g of solid acid, and stir until the solid is uniform. Put it into an ultrasonic reactor, install a reflux device, set the reaction temperature to 40-60°C, ultrasonic power to 500W, and react for 1-3 hours. The reaction solution gradually changes from white to yellow, and then to orange-red. Use HPLC to track the reaction conversion rate, the reaction is complete until the p-hydroxybenzoic acid is less than 5%, stop the reaction, filter out the solid acid catalyst, the catalyst can be used for the next reaction; the filtrate is placed at about 5-10°C for crystallization for 6-10 hours The crystals were filtered, dried at 50-60°C for 6 hours, detected by HPLC, the impurity was less than 0.1%, and 141 g of intermediate 4-hydroxy-3,5-dimethylbenzoic acid was obtained with a yield of 85%.
[0075] Above-mentioned step (...
Embodiment 2
[0089] Example 2 Preparation of 2,6-di-ethylphenol
[0090](1) In a 500ml reaction flask, add 138g (1mol) of p-hydroxybenzoic acid, 230g (5mol) of ethanol, and 50g of solid acid, and stir until the solid is uniform. Put it into an ultrasonic reactor, install a reflux device, set the reaction temperature to 40-60°C, ultrasonic power to 500W, and react for 1-3 hours. The reaction solution gradually changes from white to yellow, and then to orange-red. Adopt HPLC (method is the same as embodiment 1) tracking reaction conversion rate, react to p-hydroxybenzoic acid less than 5% and calculate reaction completely, stop reaction, filter out solid acid catalyst, catalyzer can apply mechanically next time to react; Filtrate is placed about 5 Crystallized at ~10°C for 6-10 hours, filtered the crystals, dried at 50-60°C for 6 hours, detected by HPLC, the impurities were less than 0.1%, and 155g of intermediate 4-hydroxy-3,5-diethylbenzoic acid was obtained, with a yield of 80% .
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