pH-independent decomposition reactions of L-ascorbic acid in aqueous metal solutions .1. Formation and structures of Co-II and Gd-III oxalates


UNALEROGLU C. , ZUMREOGLU KARAN B., ZENCIR Y. , Hokelek T.

POLYHEDRON, vol.16, no.13, pp.2155-2161, 1997 (Journal Indexed in SCI) identifier

  • Publication Type: Article / Article
  • Volume: 16 Issue: 13
  • Publication Date: 1997
  • Doi Number: 10.1016/s0277-5387(96)00563-3
  • Title of Journal : POLYHEDRON
  • Page Numbers: pp.2155-2161
  • Keywords: L-ascorbic acid, metal-ascorbate complexes, cobalt oxalate, gadolinium oxalate, VITAMIN-C, COORDINATION CHEMISTRY, COMPLEXES, CHROMIUM(VI), OXIDATION, IONS

Abstract

The reactions of L-ascorbic acid in aqueous Cd-II and Gd-III solutions were investigated at pH values of 2, 6 and 12. IR spectral studies revealed that the initially formed metal-ascorbates slowly decompose to the solid oxalate complexes in a pH-independent manner. The compositions of the cobalt oxalates were defined as CoC2O4 . 2H(2)O and those of Gd-III showed variations due to the stereochemical changes in the precursor ascorbate complexes related to pH. X-ray crystal analyses were performed and the structure of Gd-2(C2O4)(3) . 6H(2)O is reported for the first time. (C) 1997 Elsevier Science Ltd.