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7440-05-3

7688-25-7

29964-62-3

Example 3 Step 1: 10 mL of palladium sponge was mixed with concentrated hydrochloric acid and concentrated nitric acid in a 3:1 volume ratio until the palladium sponge was completely dissolved. 37% concentrated hydrochloric acid was added to the solution and filtered to remove insoluble material while treating the brown nitrogen oxides produced. The filtrate was concentrated to a solution of chloropalladium acid with a palladium concentration of 0.5 g/mL. Step 2: An N,N-dimethylformamide solution of bis(diphenylphosphino)butane was prepared by adding 44 g of 1,4-bis(diphenylphosphino)butane to 100 mL of N,N-dimethylformamide, and heating to 50°C. The N,N-dimethylformamide solution of bis(diphenylphosphino)butane was then heated to 50°C. Step 3: The chloropalladium acid solution prepared in step 1 was added dropwise to the bis(diphenylphosphino)butane solution in step 2 under stirring. The reaction was stirred at 50 °C for 60 minutes. After completion of the reaction, the reaction solution was cooled and filtered, and the filter cake was collected. Step 4: The filter cake obtained in Step III was washed with anhydrous ethanol and then dried under vacuum at 50 °C for 4 h. A light yellow 1,4-bis(diphenylphosphino)butane-palladium(II) chloride complex (C28H28Cl2P2Pd) of 56.1 g was obtained in 98.9% yield.