Sulfuric Acid → barium L-ascorbate 2-sulfate dihydrate

Participants

Reaction Steps

To a mixture of water (25.0) and L-ascorbic acid (2.0g, 11.5 millimoles) was added barium hydroxide octahydrate with stirring until the solution had pH 10.5. The mixture was warmed to 70°, and trimethylamine-sulfur trioxide (2.4g, 1.5 equivalent) was added. Solid barium hydroxide octahydrate was added intermittently to maintain the reaction pH at 10.5. A total of 5g of barium hydroxide octahydrate was used in the reaction to this point. After 30 minutes the reaction was complete as indicated by thin-layer chromatography. The mixture was cooled and a saturated aqueous solution of barium hydroxide (1-2 ml) was added to adjust the solution pH to 12.5. Nitrogen was passed through the mixture at 70° to expel trimethylamine. The solution was diluted with water (100 ml) and neutralized with aqueous sulfuric acid. Insoluble barium sulfate was removed by filtration, and the filtrate decolorized with charcoal and evaporated to a small volume (30 ml). Addition of methanol (30 ml) followed by cooling gave 3.94 g (80%) of barium L-ascorbate 2-sulfate dihydrate with m.p. 234°-40°.

Provenance & Evidence