Preparation of 1-(4-fluorophenyl)piperazine_Kain Industrial Additive

Background and overview^[1][2]

Substituted piperazine compounds are widely used and can be used in the synthesis of several major categories of drugs, such as antihistamines, antidepressants, antipsychotics, antitussives, etc. 1-(4-Fluorophenyl)piperazine can be used as a pharmaceutical and chemical synthesis intermediate. If 1-(4-fluorophenyl)piperazine is inhaled, move the patient to fresh air; if skin contact occurs, take off contaminated clothing, rinse the skin thoroughly with soap and water, and seek medical attention if you feel uncomfortable; If eye contact occurs, separate eyelids, rinse with running water or saline, and seek medical attention immediately; if ingested, rinse mouth immediately, do not induce vomiting, and seek medical attention immediately.

Preparation ^[1][2]

Method 1: Weigh 9.2mL (0.10mol) of 4-fluoroaniline, 17.85g (0.10mol) of bis(2-chloroethyl)amine hydrochloride and 25mL of diethylene glycol monomethyl ether into a 100mL three-necked flask in, and place it in a WBFY-201 microcomputer microwave chemical reactor equipped with a reflux device, reflux, the microwave radiation power is 800W, the reaction time is 3 minutes, the reaction is completed, and after the reaction liquid is cooled, the diethylene is distilled under reduced pressure. Glycol monomethyl ether, recycled solvent for use. Add a small amount of ethanol to the residue, and add a certain amount of ether solution. After the mixture is clarified, a large amount of solid will precipitate. Dissolve the hydrochloride in 30 mL of water, adjust the pH value to 12 with 40% sodium hydroxide, and add acetic acid. Extract with ethyl ester twice (2×40mL), then wash once with water and saturated brine once, dry the organic layer with anhydrous sodium sulfate, filter, concentrate and distill under reduced pressure to obtain 1-(4-fluorophenyl)piperazine. 13.97g of light yellow liquid, yield 77.6%.

Method 2: Add about 10 ml of catalyst solution in o-xylene (palladium atom/aryl halide ratio = 0.5%) into the dropping funnel. In a 200 ml Kjeldahl flask equipped with a dropping funnel, condenser and thermometer, at room temperature 22 g of piperazine, 7.47 g of 1-bromo-4-fluorobenzene as aryl halide (ratio of piperazine/aryl halide = 6 /1 mol) and 5.66g NaOBu t (ratio of NaOBu t /aryl halide = 1.38 / 1 (molar ratio)) were added to the flask, and the flask was flushed with nitrogen for about 20 minutes while stirring the contents and removing the contents. Heat to 80°C. At this temperature, drop the catalyst solution into the flask, heat the contents to 120°C, and stir at this temperature for 3 hours. After the reaction is completed, add 80ml of water to cool the reaction product, and remove the liquid reaction product Add to the separatory funnel and separate the organic phase. Extract the aqueous phase thus obtained with 40 ml of o-xylene. The organic phase is dried with sodium sulfate. Gas chromatography analysis of the dried product by the internal standard method shows that the target is obtained with a yield of 96%. Arylamine, namely 1-(4-fluorophenyl)piperazine.

Main reference materials

[1] CN102786496. Microwave synthesis method of substituted piperazine compounds

[2] EP0802173. Process for producing heterocylic aromatic amine or arylamine