Sodium Hydroxide → (2R)-2-phenylpropylamine malate

Participants

Reaction Conditions

Reaction Steps

Charge 2-phenyl-1-propylamine HCl (317.2 g, 1.85 moles), dry ethanol (2.0 L) and NaOH beads (75.4 g, 1.89 moles) washed with additional ethanol (500 mL) to a dry 3-L round bottom flask under nitrogen. Stir the mixture for 1.6 hours. Filter and add a solution of L-malic acid (62.0 g, 0.462 mole, 0.25 equivalents) in ethanol (320 mL) dropwise to the yellow filtrate. Heat the solution to 75° C., then stir at 75° C. for 30 minutes. Remove heat and allow the solution to cool slowly. Allow the resulting thick precipitate to stir overnight. Filter the precipitate, rinse with ethanol (325 mL) and dry under reduced pressure to afford (2R)-2-phenylpropylamine malate (147.6 g, 39.5%) as a white crystalline solid. Chiral GC analysis of the free base, 2-phenyl-1-propylamine reveals 83.2% e.e. enriched in the R-isomer. (Configuration is assigned via spectrometric comparison with commercial 2-phenyl-1-propylamine.) 1H NMR (CDCl3, 300 MHz) δ 7.32 (m, 2H), 7.21 (m, 3H), 2.86 (m, 2H), 2.75 (m, 1H), 1.25 (d, 3H, J=6.9), 1.02 (br s, 2H).

Provenance & Evidence