Verbindungen der L‐Ascorbinsäure mit Metallen. II. Titanylascorbate

Abstract

Die Titanylascorbate TiO(C6H7O6)2 · 2 H2O und TiO(OH)(C6H7O6), über deren Darstellung bereits an anderer Stelle berichtet worden ist, werden durch Elektronen‐, IR‐ und 1H‐NMR‐Spektren charakterisiert. Aus Messungen der H3O+‐Konzentration wäßriger Lösungen beider Verbindungen wird ein einfaches Modell zur Beschreibung ihres Protolyseverhaltens abgeleitet.

Complexation of boric acid with vitamin C

“…The strong peak at 1320 cm À1 and the weak peak at ca.1250 cm À1 corresponding to the (O-H) enediol for the free acid disappeared in the spectra of the complexes showing the participation of the O C3 and O C2 atoms in chelate-type coordination. 27 The spectral pattern in the 1200-800 cm À1 region is consistent with the data , which is a diagnostic for the tetrahedral borate anion, 25 was not observed. Instead, the compounds typically showed two signals at 822 cm À1 and 762 cm À1 , the latter being more intense.…”

Structural and magnetic studies on mono- and polynuclear chromium ascorbate complexes

“…Mononuclear complex (1) The synthesis was carried out following the procedure described by Jabs and Gaube [5,6]. (2) and (3) were obtained using a M40 Intectra (matrix: NBA) and EI spectrum of (1) with a Micromass UK LCMS spectrometers.…”

“…About two decades ago, a chromium ascorbate complex, synthesized directly from Cr III ions, was described by its electronic and i.r. spectra and magnetic moment [5,6]. A group of complexes, prepared via reduction of several Cr VI species by ascorbate, has since been reported [7][8][9][10].…”

Interaction of the Vanadyl(IV) Cation with L-Ascorbic Acid and Related Systems

“…S ynthesis o f the com plexes C om p lexes o f ascorbic acid: F ollow ing a g en e ral sy n th e tic p ro c e d u re o u tlin e d by Jabs a n d G a u b e [17], it w as possible to iso late d iffe ren t V 0 2+/asco rb a te co m p lex e s at d iffe re n t pH -values. …”

“…T h e o x id a tio n p ro ce ss can p ro c e e d f u rth e r to 2 ,3 -d ik eto g ulonic acid, an d h e n c e to a m ix tu re o f oxalic a n d Lth re o n ic acids [17,29]. A t p H > 9, th re o n ic acid is ox id ized to ta rta ric acid, as d e p ic te d in Fig.…”