Trifluoroacetic acid → (R)-Morpholin-2-ylmethanol 2,2,2-trifluoroacetate salt

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In the same manner as in Example 3, a mixture containing N-benzyl-2-hydroxymethylmorpholine, N-benzyl-1,4-oxazepane and other byproducts (121.1 g, N-benzyl-2-hydroxymethylmorpholine:N-benzyl-1,4-oxazepane compound=75.1:24.9). To this mixture were added methanol (200 ml), trifluoroacetic acid (61.8 g, 0.540 mol), and palladium carbon (11.0 g when dry), and the mixture was reacted under a hydrogen stream at 25° C. for 15 hr. Palladium carbon was filtered off, and methanol was evaporated under reduced pressure. The residue was subjected twice to azeotropic distillation with dehydrating with 2-propanol (100 ml). To the residue after azeotropic distillation with dehydrating was added ethyl acetate (450 ml) at 40° C., and the mixture was cooled to 20° C. Seed crystal was added and, after crystallization, the mixture was cooled to 0° C. and stirred for 1 hr. The crystals were collected by filtration, washed withed twice with ethyl acetate (100 ml) and dried (1 mmHg, 40° C.) to give (R)-2-hydroxymethylmorpholine trifluoroacetate (53.7 g) (yield from (S)-epichlorohydrin: 43.0%). The obtained (R)-2-hydroxymethylmorpholine trifluoroacetate was analyzed by HPLC to find an optical purity of 99% ee.

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