Hydrochloric Acid → Palladium

Participants

Reaction Steps

The reaction of Example 1 (reaction scale: 71.5 kg, 177.29 mol of bromophenyl pyrazole) was conducted with 0.1 mole % of Pd2(dba)3. After the reaction was judged to be essentially complete, the reaction mixture was neutralized with 1N aq. HCl to a pH of 7.0 to 7.5. The crude solid was dissolved in THF (9 L/Kg of bromophenyl pyrazole starting material), and the mixture was stirred in the presence of PS-PPh3 resin (Fluka, 3.0 wt %) at ambient temperature. After stirring for 84.5 h, the resin was removed by filtration, and the filtrate was passed sequentially through a Darco zeta pad cartridge, then a 1.2 μm Cuno polish filter. The palladium levels after the Darco pad filtration and after polish filtration were less than 10 ppm and less than 13 ppm, respectively. The filtrate was concentrated and its solute recrystallized from THF/acetone/water to afford 2′-(5-ethyl-3,4-diphenyl-1H-pyrazol-1-yl)-[1,1′]-biphenyl-3-ol containing less than 10 ppm of palladium.

Provenance & Evidence