CN201110288317.6 provides a method for preparing 2,3-dihydro-1-indanone and its derivatives. This invention combines a two-step reaction into a one-pot process, thereby reducing the need for intermediate purification, drying, and packaging, avoiding the possibility of allergies, reducing the amount of catalyst used, simplifying the operation, lowering production costs, reducing environmental pollution, and protecting worker health.
In a 1-liter three-necked flask, toluene (100 g, 1.08 mol), aluminum trichloride (405 g, 3.05 mol), and NaCl (70 g, 1.2 mol) were added and stirred. 3-Chloropropionyl chloride (140 g, 1.1 mol) was added dropwise at 5–15 °C. The molar ratio of toluene to 3-chloropropionyl chloride was 1:1, and the molar ratio of toluene, aluminum trichloride, and NaCl was 1:2.8:1.1. The mixture was stirred at 50–65 °C for 90 minutes, then at 170–180 °C for 120 minutes. After cooling to 75–85 °C, the mixture was poured into 1 kg of ice-water hydrochloric acid. The mixture was filtered to obtain 144 g of crude product. Recrystallization yielded 114 g of solid, with a yield of 72% (purity > 98%) and a melting point of 73–74 °C.
