Phenolphthalein → Sodium ethoxide

Participants

Reaction Steps

To dry ethanol (200 ml) was added 97% hydroxylamine hydrochloride (8.60 g, 0.120 mole), heated and dissolved. While maintaining the mixture below 25° C. to this stirring solution was added a solution of sodium ethoxide in ethanol which was prepared by the addition of sodium metal (2.76 g, 0.120 g-atom) to dry ethanol (56 ml). Ethyl trifluoroacetoacetate (18.4 g, 0.100 mole) was then added and heated under reflux to allow to react for 4 hours. The reaction mixture was cooled with ice and a solution of sodium ethoxide in ethanol which was prepared by the addition of sodium metal (2.30 g, 0.100 g-atom) to ethanol (46 ml) was added and allowed to stand overnight at 0° C. A slight amount of phenolphthalein as an indicator was added and, while cooling with ice, a solution of soidum ethoxide in ethanol was added until the reaction mixture was colored to pale red. The precipitated inorganic crystals were filtered off. The crystals were well washed with dry ethanol (40 ml) and the washings were combined with the above filtrate and ethanol was evaporated under reduced pressure at 40° C. To the resulting residue was added benzene, the solvent was evaporated under reduced pressure, and then the residue was dried under reduced pressure (<1 mmHg) at 100° C. for 1 hour to give 18.06 g of crude 3-trifluoromethyl-5-hydroxyisoxazole sodium salt (crude yield 103.2%, yield calculated as the pure product 79.2%) as a pale pink amorphous material.

Provenance & Evidence