DL-HOMOPROLINE TETRAHYDRATE

Crystals of the title compound C6H11NO2.cntdot.4H2O, FW = 153.2, are monoclinic, P21/c, a = 13.404 (7), b = 6.510 (4), c = 12.962 (8) .ANG., .beta. = 108.94 (2).degree., Z = 4, Dm (by flotation) = 1.23, Dx = 1.222 Mg m-3, F(000) = 440, Cu K.alpha. radiation (.lambda. = 1.54178 .ANG., .mu. = 0.96 mm-1). The structure was refined to R = 0.079 for 1695 counter reflections. The molecule exists as a zwitterion. The piperidine ring has a chair conformation with the carboxyl group equatorial. There are 4 water molecules/asymmetric unit, which almost surround the amino acid. Two of the water molecules are coordinated to the homoproline by H- bounds while the other 2 are H- bounded to each other.