To a stirring suspension of 650 mg (1.89 mmol) of (+)-(5)6-methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole in 6.5 mL of methyl ethyl ketone (MEK) in a 50 mL flask was added at ambient temperature 0.39 mL of a 5M aqueous sodium hydroxide solution. To that mixture was added 13 mL of toluene. The resulting mixture was turbid, so an additional 6.5 mL of MEK was added and the mixture became a clear, yellow solution. This mixture was allowed to stir at ambient temperature overnight. The following morning, several crystals of 6-methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole sodium salt were added to act as seed crystals, but no product crystals formed. A stream of dry nitrogen gas was blown over the mixture to begin removing the solvent. After approximately 10 minutes, the product precipitated. The solids were isolated by vacuum filtration and washed with a small amount of diethyl ether. The solids were then placed into a vacuum desiccator to remove the last traces of ether, to yield approximately 500 mg of the desired product as an off-white powder.
