28874-51-3Relevant articles and documents
Zinc pyrrolidonecarboxylate dihydrate and method of producing the same
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Page/Page column 7, 8, (2008/06/13)
The present invention aims at providing a convenient method of producing zinc pyrrolidonecarboxylate dihydrate, which is an industrially useful compound, with high optical purity, a higher yield, and better dissolution property. The present invention also provides a convenient method of producing zinc pyrrolidonecarboxylate dihydrate with higher optical purity, a higher yield, and better solution property by adding a zinc salt to an aqueous medium containing a salt of pyrrolidonecarboxylic acid as a starting material and separating a crystal from the aqueous medium at a specific pH.
Metal Binding by Amino Acids: Preparation and Crystal Structures of Lithium, Sodium, and Potassium Hydrogen Bis-L-pyroglutamate
Kumberger, Otto,Riede, Juergen,Schmidbaur, Hubert
, p. 1829 - 1834 (2007/10/02)
Lithium, sodium and potassium bis-L-pyroglutamate , , and , respectively, have been prepared by reaction of aqueous solutions of the metal hydroxides with L-pyroglutamic acid in the molar ratio 1:2, or in methanol.Crystalline samples of the salts could be obtained by slow evaporation of solutions of the salts in methanol.In the solid state, Li(L-pGlu)(L-pGluH) adopts a chain structure with the lithium atoms arranged in double strands.Adjacent metal centers are bridged by the carboxylate groups of the L-pGlu- ligands.The L-pGluH ligands are attached to the metal centers through the amide oxygen atoms.Na(L-pGlu)(L-pGluH) forms a three-dimensional coordination polymer with two half-occupied sodium positions, one L-pGlu- and one L-GluH ligand in the asymmetric unit.The carboxyl and carboxylate groups of the L-pGluH and the L-pGlu- ligands are bridging the sodium centers, giving rise to eight-membered rings, which consist of two sodium atoms, a carboxyl and a carboxylate group.The hydrogen atoms of the carboxyl group of the L-pGluH ligands are involved in strong hydrogen bonds between a carboxyl and an adjacent carboxylate oxygen atom.K(L-pGlu)(L-pGluH) adopts a layer structure with strands of potassium atoms.The metal centers are connected through bridging carboxyl and carboxylate groups of the L-pGluH and L-pGlu- ligands, respectively.The structure features eight-membered ring units comparable to those observed for Na(L-pGlu)(L-pGluH), again with the hydrogen atom of the carboxyl group engaged in a strong transannular hydrogen bond.The amide oxygen atoms of the L-pGlu- and the L-pGluH ligands are coordinated to the metal centers of adjacent coordination chains.The results of 1H- and 13C-NMR investigations of aqueous solutions of the compounds indicate extensive electrolytic dissociation in diluted solutions. Key Words: Hydrogen bis-L-pyroglutamates, lithium, sodium, potassium / Pyroglutamate coordination and conformation
