4,4-Difluoropiperidine hydrochloride

Synthesis

Add 20 kg of dichloromethane to a 50 L dry four-necked flask in one go, followed by 2 kg of Al in one go. The internal temperature is 25 °C, and the addition takes place over 10 minutes. The internal temperature remains constant during the addition process. Afterward, cool the flask to 15-20 °C and replace the reaction system with argon gas. Add 2.2 kg of trifluorothiomorpholine dropwise over 240 minutes. The addition process is exothermic and gas-releasing but relatively gradual. Keep the internal temperature below 30 °C, then stir at 25-30 °C for 10 hours. The stirring process is easy. The reaction is monitored by TLC (PE:EA = 3:1) using ninhydrin as a colorimetric reagent. The results show that the starting materials have reacted completely and new product spots have formed. GC analysis shows that the product content is 95% and the elimination product content is 2%.

Uses

4,4-Difluoropiperidine hydrochloride is a piperidine derivative, and as a pharmaceutical intermediate, it is in high demand. It is also an important fragment of novel histamine-3 receptor antagonists.

Chemical Properties

White solid