Chromate, tris racemization

In aqueous solution potassium tris(oxalato)chromate(III) racemizes faster than the analogous cobalt compound but more slowly than the corresponding iron compound. Many studies of the racemization rate have been made under various conditions. - The rate is dependent on the nature of the solvent it is lowered by addition of organic solvents to aqueous solutions. - Both enantiomers have been the subject of numerous optical rotatory dispersion studies.No exchange has been shown to occur between oxalate ion containing radioactive carbon and the tris(oxalato)-chromate(III) ion. ... 

Chromate, tetrakis(dioxygen)-stereochemistry, 94 Chromate, tricyanodiperoxy-structure, 78 Chromate, tris(oxalato)-racemization solid state, 466 strychnine salt racemization, 466 Chromatography optical resolution, 26 Chrome azurol S metallochromic indicator, 556 Chromium... 

Five grams (0.0127 mol) of (-t-)-bis(l,2-ethanediamine)(oxalato)-cobalt(III) iodide ([a] = -1-720°) is converted to the acetate by shaking for 10 min with 2.11 g (0.0126 mol) of solver acetate suspended in 30 mL of hot (50°) water contained in a 100-mL flask. The precipitated silver iodide is removed by filtration and washed with 10 mL of hot water. The combined red filtrate and washings are added with stirring to a solution of 2.00 g (0.00409 mol) of racemic potassium tris(oxalato)chromate(III)... 

Although Werner considered both enantiomers of potassium tris-(oxalato)chromate(III) to be monohydrates, Charonnat and Dele-pine, on the basis of isomorphism with the corresponding iridium salt, proposed that they are dihydrates. The (+) enantiomer has been described as bluish red in the dry, pure condition. - The optical enantiomers are less soluble in water than the racemic mixture. Because of the high rate of racemization in water, recrystallization has been reported to be accompanied by a considerable loss of optical rotation. For the same reason, the optical rotation values reported by different workers are not directly comparable. ... 

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