preparation | step 1. 2-(4-hydroxyphenyl)-4-methyl -5-thiazolate ethyl acetate hydrochloride, I .e. synthesis of 152A2-20 add 960g DMF to the reaction bottle, add 240g(1.965mol)4-hydroxybenzaldehyde, stir evenly, and then add 138g(1.986mol) hydroxylamine hydrochloride; The oil bath is heated to 110~120 ℃, the reaction system becomes a uniform solution, and the reaction is stirred for about 6 ~ 7hr; after the reaction is completed, the reaction liquid is cooled to 10~20 ℃. Add 320g(4.320mol) of sodium hydrosulfide monohydrate into the pressure kettle, add the cooled reaction liquid into the pressure kettle, and seal the pressure kettle; Stir, the reaction liquid exotherms itself, the temperature will rise to about 50~80 ℃, and the pressure in the kettle will increase to 3 ~ 5atm. Heat preservation at 70~80 ℃ for 6 ~ 8hr. After the reaction is completed, the reaction liquid is cooled to 30~40 ℃, the pressure is relieved, the reaction liquid is transferred to other reaction bottles, about 240~250g of concentrated hydrochloric acid is added, the temperature is kept at 30~40 ℃, and the low boiling point substances are removed under reduced pressure, about 3 ~ 4hr. Add 960g of anhydrous ethanol to the residue, control the temperature not more than 60 ℃, add 325g(1.975mol)152B2-00 (ethyl 2-chloroacetoacetate) dropwise, raise the temperature to 70~80 ℃, and reflow reaction is about 3 ~ 4hr; After the reaction is completed, the reaction solution is cooled to 5~10 ℃ and kept for about 1 ~ 2hr. Filtering, collecting solid is 152A2-20 crude product (which contains some inorganic salts), then dispersing 152A2-20 crude product in 1500g of water, keeping the temperature at 20~30 ℃ and beating for about 2hr; Filtering, leaching with anhydrous ethanol, collecting solids, blowing and drying at 65~75 ℃ to obtain 152A2-20 dry product of about 538g (theoretical quantity: 589.1g, calculated as 4-hydroxybenzaldehyde). Yield: 91.3%. Step 2. 2-(3-aldehyde -4-hydroxyphenyl)-4-methyl thiazole -5-carboxylate ethyl ester, namely 152A3-00 synthesis Add 2000g of polyphosphoric acid (based on phosphoric acid, the concentration is about 116%), the temperature is controlled not more than 80 ℃, and then add 1000g of concentrated phosphoric acid (concentration is about 85%); Keep the temperature at 70~80 ℃ and stir for about 2hr; Cool to 40~50 ℃, add 360g(1.201mol)152A2-20, then add 220g(1.569mol) urotropine; The reaction solution is heated to 90~95 ℃, and the temperature is kept for 3 ~ 5hr. After the reaction is completed, the reaction liquid is cooled to 40~60 ℃, and slowly added to 6000g of ice-water mixture. During the quenching process, the temperature is controlled not more than 40 ℃; After quenching, keep the temperature at 30~40 ℃, stir for about 3 ~ 4hr; Cool to 20~25 ℃, and heat preservation and crystallization for about 1hr. Filtering, rinsing with water, collecting solid is 152A3-00 crude product, adding the obtained crude product to 450g ethanol, heating to 60~70 ℃, then cooling to 0~10 ℃, heat preservation and crystallization about 2 ~ 3hr. Filtration, leaching with ethanol, solid collection, drying to obtain 152A3-00 dry product of about 263g (theoretical quantity: 349.9g). 75.2% yield. |