772-14-5

optical purity >99%

Purify the acids as the 2-isomer above, i.e. by distillation, but under a good vacuum. [Prelog & Scherrer Helv Chim Acta 42 2227 1959, Levene & Marker J Biol Chem 93 761 1932, 100 685 1933, Cram J Am Chem Soc 74 2137 1952.] The R-amide crystallises from H2O, with m 101.5-102o, and [] 20 -16.5o (c 1.2, EtOH). The racemic acid has m 39-40o, b 134-136o/6mm, 158o/12mm [Marvel et al. J Am Chem Soc 62 3499 1940]. [Beilstein 9 IV 1813.]