Tartaric acid, first analysis

Alkali metal complexes may be analyzed for their metal content by simple acidimetric titration. Analysis for adduct (hydroxide) content is more involved, and entails the assumption that there can be no water of hydration attached to an alcoholate anion. The method involves first, dissolving the complex in anhydrous methanol, and then, treating the resulting solution with an appropriate anhydrous add, such as tartaric acid. The acid serves to convert any hydroxide ion into water (reaction S),... 

But how do we know in the first place that (—)-2-methyl-l-butanol has configuration III Its configuration was related in this same manner to that of another compound, and that one to the configuration of still another, and so on, going back ultimately to (4-)-tartaric acid and Bijvoet s x-ray analysis. 

To determine the absolute configuration of optically active organic compounds, there are two nonempirical methods. One is the Bijvoet method in the X-ray crystallographic structure analysis, which is based on the anomalous dispersion effect of heavy atoms. - The X-ray Bijvoet method has been extensively applied to various chiral organic compounds since Bijvoet first succeeded in determination of the absolute stereochemistry of tartaric acid in 1951. The second method is a newer one based on the circular dichroism (CD) spectroscopy. Harada and Nakanishi have developed the CD dibenzoate chirality rule, a powerful method for determination of the absolute configuration of glycols, which was later generalized as the CD exciton chirality method. 8 The absolute stereochemistry of various natural products has been determined by application of this nonempirical method. 

The evaluation of alkaloids content may be effected on the basis of color tests by the Van Urk reaction (Pharm. Weekbled 66, 1929, p. 473) after extraction as follows the culture broth is alkalinized to pH 8 and extracted first with chloroform and then re-extracted with the aqueous acidic solution (e.g., 1% H2S04 or 2% tartaric acid) which is used for the colorimetric analysis of alkaloids. 

Some intrinsec metal characteristic features are also indicated by EXAFS analysis of these catalysts. By comparing the Fourier transforms of the tartaric acid treated catalysts with those of the standard compounds, a similarity to RuOj is quite evident in the first 4 A of the transforms. This claims for a quite oxidated state of the local Ru-environment in these catalysts. The. shift of the first radial maximum towards larger distances, characteristic of the Ru-Cl bond, suggests a certain Cl contribution to the local environment of Ru, however still dominated by the oxygen of the support... 

Hydride generation increases the power of detection of atomic spectrometric methods for the determination of certain elements, and allows their matrix-free determination. However, the technique is prone to a number of systematic errors. First, the hydride-forming elements must be present as inorganic compounds in a well-defined valence state. This may require sample decom x>sition prior to analysis. In water analysis, treatment with H2SO4/H2O2 may be effective [106]. Traces of heavy metals such as Cu" may have a catalytic influence on the formation and dissociation of the hydrides, as investigated by Welz et al. [107] in atomic absorption with quartz cuvettes. These in-terferents can be masked by complexation with tartaric acid or coprecipitated with La(OH>3. Calibration by standard addition is advisable. 

If the crystal-structiu-e analysis is made on a derivative containing a heavy atom, with x-rays of wavelength appropriate to the particular heavy atom (that is, Br or I with CuKa radiation), it is possible to determine the absolute configuration of an enantiomorphous molecule. This method was first demonstrated with the rubidium sodium salt of dexiro-tartaric (l-threaric) acid tetrahydrate by Bijvoet and coworkers in 1951. The results confirmed the configuration of dextro-i vi nc acid originally assigned by... 

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