To crude crystals (31.9 g) of ethyl di(4-docosoxyphenyl)methylcarbamate were added toluene (300 mL), ethanol (200 mL), and sodium hydroxide (4.2 g, 105 mmol), and the mixture was refluxed under stirring at 100° C. Sodium hydroxide (total 9.8 g, 245 mmol) was added, and the mixture was stirred for 16 hours. The reaction mixture was cooled to room temperature, and water (300 mL), hexane (200 mL) and ethyl acetate (200 mL) were added for partitioning. The aqueous layer was discarded, and the organic layer and precipitated crystals were washed with water (300 mL×2). The organic layer and crystals were recovered. The solvent was evaporated under reduced pressure. To the residue were added water (150 mL) and acetonitrile (150 mL) to allow crystallization. The crystals were collected by filtration and thoroughly washed with water and acetonitrile to give di(4-docosoxyphenyl)methylamine (28.1 g, 33.7 mmol, 98% vs —OH).
