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organic compounds
A new crystalline modification of proline was identified by the present X-ray analysis as a monoclinic L-proline monohydrate, C5H9NO2.H2O. The pyrrolidine rings are in a C2.Cγ-exo-Cδ-endo conformation. The C4 atom (Cγ) is in a trans position with respect to the carboxyl group. In the crystal lattice, columns of L-proline molecules are stabilized by intermolecular hydrogen bonds. These columns are interconnected by water molecules. The water molecules in the structure form non-linear hydrogen-bonded chains parallel to the c axis. One H atom of the water molecule chain is disordered.