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ChemicalBook CAS DataBase List 9-Carboxyfluorene
1989-33-9

9-Carboxyfluorene synthesis

12synthesis methods
-

Yield:1989-33-9 80.7%

Reaction Conditions:

with hydrogenchloride;nitrogen;acetic acid in water;toluene

Steps:

1 EXAMPLE 1
EXAMPLE 1 10% of a solution of 332 g (1.9 moles) of fluorene and 974 g (8.2 moles) of diethyl carbonate was added to a mixture of 974 g (8.2 moles) of diethyl carbonate and 120 g (4 moles) of sodium hydride in a reaction vessel and the mixture was heated at 65° C. with stirring. At the start of hydrogen evolution, nitrogen was introduced over the surface of the reaction mixture and the remaining 90% of the fluorene solution was added to the mixture at 65° C. over 90 minutes. The mixture was stirred at 60° C. for 4 hours and was cooled to 20° C. The reaction mixture was slowly poured into a mixture of 400 g (4 moles) of concentrated hydrochloric acid and 500 g of water cooled with water to prevent the temperature from rising above 40° C. The mixture was filtered and the filtrate was decanted. The organic phase was evaporated to dryness under reduced pressure and the distillate was 1700 ml of diethyl carbonate. A mixture of the distillation residue, 1,049 g of acetic acid and 420 g of 10% hydrochloric acid was refluxed for 4 hours and after about 30 minutes, crystals of fluorene-9-carboxylic acid began to precipitate from the refluxing mixture. After the 4 hours, the mixture was cooled to20° C. and was vacuum filtered. The recovered product was washed with 600 ml of toluene and then with 500 ml of water at which time the wash water was free of chloride ions. The 360 to 400 g of product was dried at 80° C. to obtain 322 g of fluorene-9-carboxylic acid in the form of light beige crystals melting at 226°-230° C. (80.7% yield based on fluorene).

References:

Rutgerswerke Aktiengesellschaft US4564700, 1986, A

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