Hydrochloric Acid → p-Toluenesulfonic acid

Participants

Reaction Steps

To 40 mL of methanol, 4.52 g (19.2 mmol) of the hydrochloric acid salt similarly produced and 3.65 g (19.2 mmol, 1.00 eq) of p-toluenesulfonic acid monohydrate were added. Dissolving under heating was made at 40 to 50° C., and methanol was concentrated under reduced pressure. Then, 27 mL of isopropanol and 6 mL of n-heptane were added to the residue, and dissolving under heating was made at 90° C., followed by gradually lowering the temperature to room temperature. Precipitated crystal was filtered and washed with a small amount of n-heptane, followed by being dried under vacuum, thereby obtaining 6.12 g of p-toluenesulfonic acid salt of α-trifluoromethyl-β-substituted-β-amino acids. The recovery was 86%. The diastereomer ratio was syn-body:anti-body=>98:2 according to 1H-NMR and 19F-NMR analyses.

Provenance & Evidence