2-Chloro-4-fluorotoluene

Chemical Properties

Uses

General Description

Synthesis

95-74-9

452-73-3

1. In a 1 L reactor (equipped with a condenser and a gas phase outlet diameter of 1/6 to 1/5 the diameter of the reactor), reduce the temperature to 20°C or lower. Slowly add 424 g (21.2 mol, 20 equiv.) of anhydrous hydrogen fluoride under stirring conditions, and further reduce the temperature after the addition is complete. 2. 150 g (1.059 mol, 1 eq.) of 3-chloro-4-methylaniline was added dropwise at 5 °C or lower, with the dropwise acceleration controlled to maintain the reaction temperature in the range of 5 to 15 °C, and the final addition was completed at about 3 °C. 3. after completion of the spiking, the temperature was lowered to 5 °C or lower, 73.1 g (1.06 mol, 1 eq.) of sodium nitrite was added in batches, and the reaction temperature was controlled to be in the range of -5 to 15 °C for 4 hours, followed by a heat hold for 1 hour. 4. Upon completion of the reaction, the reactor was programmed to warm up (strictly control the rate of warming: 0.5 to 1 °C per hour in the range of 0 to 20 °C; 1 to 2 °C per hour in the range of 20 to 80 °C), and was finally warmed up to 80 °C and held for 2 hours. 5. At the end of the holding time, reduce the temperature to 30 to 35°C and leave to stratify. The organic layer was neutralized to pH 7-8 with a dilute alkaline solution, followed by hydrodistillation. 6. 141 g of the organic layer at room temperature was collected and purity was 93.4% by gas chromatography. By distillation 125.1 g of the target product 2-chloro-4-fluorotoluene was obtained in 81.8% yield and 99.9% purity by gas chromatography.

References