| 摘要 |
The invention relates to an improved process for preparing a disodium salt of 5,5'-[(2-hydroxy-1,3- propanediyl)bis](oxy)bis[4-oxo-4H-1-benzopyran-2- carboxylic acid], or disodium salt of cromoglicate, which is used as an asthma drug, by hydrolysing the diethyl ester of 5,5'-[(2-hydroxy-1,3-propanediyl)bis(oxy)]bis[4- oxo-4H-1-benzopyran-2-carboxylic acid] with the aid of diethylamine, triethylamine or tert-butylamine in a 70- 80% aqueous solution of dimethylformamide, methanol or ethanol by means of boiling the reaction mixture under reflux for 2-8 h. The ammonium salt of cromoglicate, which is thereby formed and which is readily soluble in the reaction mixture, is reacted, after treatment with active charcoal and filtering, with sodium acetate, in association with which the disodium salt of cromoglicate precipitates out. After the reaction mixture has been cooled to approx. 15 degree C, the pure disodium salt of cromoglicate is recovered by filtration.
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