2,3,5,6-Tetrafluorobenzyl alcohol

Chemical Properties

white to almost white crystalline mass

Synthesis

Weighed 20.5g pentafluorobenzonitrile, 0.2g 10% Pd/C (Baoji Ruike Pharmaceutical Chemical Co., Ltd. production), 70mL THF, 9.5g acetic acid was added to a 250mL autoclave, nitrogen replacement gas three times, pass H2 to the pressure of 10atm, warming to 55 , the reaction of 10h, the analysis of samples, raw materials disappeared, filtration of insoluble material, decompression and recovery of The solvent was recovered under reduced pressure and 25.6g of acetate of pentafluorobenzylamine was obtained, content: 97.9% (HPLC), yield: 93.8%.

Add 25.6g of acetate of pentafluorobenzenemethanamine to 100g of water, slowly add 10.2g of concentrated sulfuric acid, keep the temperature at 55, add 20g of 40% NaNO2 aqueous solution dropwise, use starch-potassium iodide test paper to test the solution until the paper turns blue, continue stirring for 1h and then raise the temperature to 85, after hydrolysis for 6h, cool to room temperature, separate out the organic phase to recover solvent and dry. Obtained 18.1g, that is pentafluorobenzyl alcohol, content: 97.3% (GC), yield: 91.8%.

Take 9.9g of pentafluorobenzyl alcohol added to 30mL of methanol, warm up to 50 , add 5.1g of Zn powder in batches, add 5.5g of concentrated hydrochloric acid slowly and dropwise, and keep the reaction at 50 for 30h, and the GC detection was done to the disappearance of raw materials, and the insoluble material was filtered out, and extracted by 225mL of methylene chloride, and then the organic phase was combined and dried with anhydrous Na₂SO₄SO₄. sub>4 drying, after evaporating the organic solvent at atmospheric pressure, then distilled under reduced pressure to collect the fraction at 84-86C/10.8 mmHg, yielding 8.0 g of product, content: 99.0% (GC), yield: 88.8%, mp: 34-36C.