Preparation background and overview of tricyclohexylphosphine tetrafluoroborate
Tricyclohexylphosphine tetrafluoroborate plays a wide range of roles in modern organic synthesis and practical applications. It is mainly used as a ligand in coupling reactions such as Buchwald and Suzuki, and in organic catalysts and transition metal complex catalysts. It is widely used in the synthesis of substances such as sunscreens, boric acid photofunctional complexes, etc.
Preparation of tricyclohexylphosphine tetrafluoroborate
A method for preparing trialkylphosphine fluoroborate. The raw material alkyl Grignard reagent is reacted with sodium phosphorus carbonate tribromide at low temperature. Fluoroboric acid is added to form a salt, followed by extraction, concentration, recrystallization, and cooling to precipitate the tribromide. Alkylphosphine fluoroborates.
Specific process:
Add 76.8g magnesium and 300g cyclohexyl chloride tetrahydrofuran solution into a 2000 mL round-bottomed flask equipped with a nitrogen protection device and mechanical stirring. Control the temperature to ≤40°C, add iodine to initiate, add cyclohexyl chloride tetrahydrofuran solution dropwise using a constant pressure dropping funnel, control the temperature to 60-65°C, complete the dropwise addition, stir and reflux for 2 hours. Under argon protection, prepare a solution of 110.2g phosphorus tribromide in 960mL methyl tert-butyl ether, lower the temperature from -15 to -10°C, add Grignard reagent dropwise to it, keep it warm for 1 hour, raise the temperature and reflux for 4 hours, and then cool to 5 after the reaction is completed ℃, keep the temperature at 5-20℃, add 704mL of 15% ammonium chloride dropwise, and then add 480mL of water, layer the lower water layer, the upper layer of light yellow oil, and extract the water layer once with 480mL MTBE. Combine the MTBE layers, recover MTBE under reduced pressure at 25-30°C, and obtain 328g of oil. Immediately add 1000mL dichloromethane and 316.8mL fluoboric acid (15%, 2.0eq), and stir for 2 hours. Layer the lower oil layer and the upper water layer. Extract the water layer once with 280 mL of methylene chloride, combine the methylene chloride layers, add 128g of sodium sulfate to dry it, and filter with water content less than 0.5%. Distill under reduced pressure at 25-30°C to recover the methylene chloride to obtain 297.2g of product. Add 220 mL of ethanol and raise the temperature to 55°C. Stir to dissolve, add 440mL MTBE, cool down the temperature naturally, stir for 2 hours, filter, wash the filter cake with 220mL MTBE (yellow substance is washed out) and dry to obtain 145g of the product tricyclohexylphosphine fluoroborate, the yield is 49%, and the mother liquor can be recovered 5% Products above, melting point 164-170℃, nuclear magnetic purity 97%.
