Preparative method of obtaining L- and D-2-hydroxy-3-methylbutyric acids

Summary A preparative method was developed for obtaining L-and D-2-hydroxy-3-methylbutyric acids by the separation of racemic 2-hydroxy-3-methylbutyric acid with the aid of D-and L-threo-2-amino-1-p-nitrophenyl-1,3-propanediols.     

Protonated Sodium 1-Hydroxyethane-1,1-diphosphonates

Powder X-ray diffraction study of sodium salts of 1-hydroxyethane-1'1-diphosphonic acid (H₄L)of the compositions NaH₃L·H₂O, Na₂H₂L·4H₂O, Na₃HL·5.5H₂O showed that these compounds aresingle-phase. Some of their properties were determined. The possibility of preparing salts of other compositionswas examined.     

The effect of thermal processing on PVC—VI. The role of hydrogen chloride

The reaction between cumene hydroperoxide (CHP) and anhydrous hydrogen chloride under various conditions of temperature and concentration has been studied in an inert solvent (chlorobenzene) and in an oxidisable medium (cumene). The kinetics were first order with respect to each reactant; the energy of activation of the overall second-order reaction was 53.4 kJ mol^?1 K^?1. Competing ionic and free radical mechanisms were found to operate, the latter predominating at relatively high HCl concentrations, leading to rapid pro-oxidation in cumene. The effect of typical organo-tin PVC stabilizers on the pro-oxidant process were examined. It was found that dibutyltin maleate neutralized the HCl thus eliminating the pro-oxidant effect when used in stoichiometric proportions, but had little other effect. Dioctyltin bis(isol-octylthioglycollate) on the other hand not only neutralized the HCl stoichiometrically but gave additional oxidative stabilization over a wide concentration range.     

Reaction of 3,4-diaminofurazan with β-keto esters

The reaction of some linear and cyclic -keto esters with 3,4-diaminofurazan was investigated. Products of condensation at the keto group and the corresponding furazanodiazepinones were isolated and characterized. The structures of the compounds obtained are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1196–1199, September, 1978.     

Chemistry of indole

5-Methoxy-3-carbethoxyindoles are nitrated primarily in the 4 position. Replacement of the methoxy group by an acetoxy group leads to a change in orientation — only the 6 isomer is obtained. In the case of the similarly constructed 5-hydroxyindoles, monosubstitution cannot be accomplished under various conditions, and only the 4,6-dinitro derivative is formed. The synthesis of the corresponding amines by reduction of the nitro compounds is described.See [1] for communication XXXVIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1646–1653, December, 1973.     

Investigation of low-temperature regeneration of activated carbon

Granular activated carbon loaded with aniline,o-nitroaniline oro-nitrophenol, regenerated at relatively low temperature (450° in N₂ atmosphere), shows losses of cyclic adsorption performances (about 5 % per cycle) comparable to those occurring with standard thermal regeneration (950° in controlled atmosphere). Adsorbate build-ups and related surface modifications have been determined.

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Zusammenfassung Mit Anilin,o-Nitroanilin undo-Nitrophenol beladene, bei relativ niedriger Temperatur (450° in N₂-Atmosphäre) regenerierte granulierte Aktivkohle, zeigt zyklische Verluste der Adsorptionsleistung (etwa 5 % je Zyklus), welche mit den bei thermischer Standard-Regenerierung (950° in gesteuerter Atmosphäre) vorkommenden vergleichbar sind. Der Aufbau der Adsorbate und die damit verbundenen Oberflächenänderungen wurden bestimmt.

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Résumé Le charbon actif en granulés, chargé d'aniline, d'o-nitroaniline et d'o-nitrophénol, régénéré à une température relativement faible (450° dans une atmosphère d'azote) montre des pertes de rendement d'adsorption cyclique (environ 5 p.c. par cycle) comparables à celles qui ont lieu lors de la régénération thermique standard (950° en atmosphère contrôlée). On a déterminé la constitution des adsorbats et les modifications relatives de surface.

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, , -, - – 450° . , ( 5% ) – 950° . .

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Work supported by IRSA-CNR, contract no. 77.01823.11.

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Thanks are due to Mr. L. Pace for skilful contribution to the experimental work.