Stereochemical correlation of diastereomeric 3-amino- with 3-arylamino acids,and their derivatives via stereospecific N-phenylation by diphenylhalonium salts

Diphenylhalonium salts were used in stereospecific N-phenylation of racemic and optically active 3-amino-2,3-diphenyl-1-propanols leading to 3-anilino-2,3-diphenyl-1-propanols. The absolute configurations of the latter and of genetically related compounds were established.

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Stereochemische Korrelation von diastereomeren 3-Amino- mit 3-Arylaminosäuren bzw. ihrer Derivate durch stereospezifische N-Phenylierung mit DiphenylhaloniumsalzenKurze Mitteilung

Zusammenfassung Durch stereospezifische N-Phenylierung mit Hilfe von Diphenylhaloniumsalzen werden racemische sowie optische aktive 3-Amino-2,3-diphenyl-1-propanole in die entsprechenden 3-Anilino-2,3-diphenyl-1-propanole übergeführt. Auf Grund dieser Umwandlung wird die absolute Konfiguration der Aminoalkohole und davon abgeleiteter Derivate ermittelt.

     

Thermal behavior and characterization of solid-state chlorinated polyethylenes

The melting behavior of solid-state chlorinated polyethylene samples of various average molar mass has been studied by employing the differential scanning calorimetry method. Both the thermal and thermodynamic characteristics of the as-prepared chlorinated powdery polymer samples were found to be essentially different, compared to those of the melt-crystallized ones. The changes in the corresponding values depended mainly on the content of the comonomer units such as chloromethylene and dichloromethylene groups and their distribution along the polymer chains. Therefore, it can be assumed that the order of the polymer crystals arrangement is disturbed in the course of both the chlorination process and the subsequent melt crystallization.     

Low-Temperature Catalytic Oxidation of Sulfide Ions in Aqueous Solutions on a Ni-Oxide System

Catalytic oxidation of sulfide ions in aqueous solutions by air oxygen has been investigated using a Ni-oxide system as a catalyst. The kinetics and the selectivity of the oxidation process were studied by varying the pH, catalyst amount and reaction temperature. A reduction/oxidation mechanism of the reaction has been supposed comprising interaction between the surface active oxygen of the catalyst and HS^– and reoxidizing of the reduced catalyst by the dissolved oxygen. The results obtained show that the Ni-oxide system is a promising catalyst for practical application.     

Low-temperature aqueous phase oxidation of cyanide ions with the participation of nickel oxide system

The low-temperature oxidation of cyanide ions to CO₂ and N₂ in an aqueous phase in the presence of Ni-oxide system has been studied. The effect of pH, temperature and catalyst amount on the rate and selectivity of the oxidation process have been investigated. A kinetic model of the reaction studied is proposed based on the experimental results. It can be used to develop a catalytic method for purification of CN containing wastewaters.     

Active Oxygen in Oxide Catalytic Systems for Environmental Catalysis

The effect of the synthesis conditions of individual and modified with Mn Ni- and Co-oxide systems on the content and the mobility of their active oxygen has been studied by means of chemical and IR spectral analyses. The results obtained show that the main part of the active oxygen in Ni-oxide system is located on the catalyst’s surface (O_s ^* is approximately 73% of the total active oxygen), while Co-oxide system is characterized by much lower surface active oxygen content. Ni- and Co-oxide systems modified with Mn have comparatively higher active oxygen content as compared to the individual ones. Data of the IR spectral analysis reveal that Mn, as a modifying component, affects the mobility of the active oxygen, the latter contributing to the activity of oxide systems in oxidation processes. The high content of loosely bonded active oxygen formed during the synthesis determines a high catalytic activity of the studied samples in reactions of complete oxidation in the low temperature region.     

Catalytic degradation of methylene blue in aqueous solutions over Ni- and Co- oxide systems

The oxidative catalytic degradation of the cationic dye methylene blue (MB) with NaOCl in aqueous solutions was studied using individual and iron modified Ni- and Co-oxide systems as catalysts. The adsorption extent and the contribution of the uncatalyzed oxidation on the overall degree of MB were determined. The results indicate that methylene blue—a representative of a class of dyestuffs resistant to biodegradation—could be successfully decolorized and degraded using nickel and cobalt oxide catalysts at room temperature. The highest catalytic activity manifests in the Co-oxide system which is consistent with the adsorption data. The oxidative degradation reaction proceeds via first-order kinetics. Temperature has a relatively small effect on the methylene blue degradation kinetics. The results obtained reveal that the catalysts investigated are suitable for oxidative destruction of methytlene blue dye in wastewaters.      

Reactivity of sodium arenesulfinates in the substitution reaction to γ‐functionalized allyl bromides

The kinetics of nucleophilic bimolecular substitution reactions of γ‐functionalized allyl bromides with non‐substituted and p‐substituted sodium arenesulfinates has been studied. Both the structure of allyl bromides and nucleophilicity of arenesulfinate ions exerted a significant effect on the values of the kinetic parameters such as the second‐order rate constants k, activation energy E_A, and changes in the entropy ΔS^≠, enthalpy ΔH^≠, and free energy ΔG^≠ of the formation of the activated complex from reactants. Based on the evaluation of kinetic parameters, the reactants could be arranged, according to their decreasing reactivity in the S_N2‐reactions as follows: p‐toluenesulfinate ion > benzenesulfinate ion > p‐chlorobenzenesulfinate ion and 4‐bromo‐2‐butenenitrile > 1,3‐ dibromopropene, respectively. Comparison was also made between the kinetic data obtained and some delocalization reactivity indexes for both the substrates and nucleophiles. The enthalpy–entropy compensation effect was observed for the reactions of sodium arenesulfinates with γ‐functionalized allyl bromides. Copyright © 2009 John Wiley & Sons, Ltd.     

Efficient One‐Pot Friedel–Crafts Acylation of Benzene and its Derivatives with Unprotected Aminocarboxylic Acids in Polyphosphoric Acid

A number of aminobenzophenones have been synthesized by acylation of benzene and its derivatives with different 2‐,3‐,4‐aminobenzoic and 4‐aminophenylacetic acids in polyphosphoric acid via Friedel–Crafts reaction as compounds with expected antitumor activity.     

Mechanically Stable Hydrophilic Films Based on Oxialkylated Macromers Polymerizable by UV Irradiation

The preparation and characterization of films based on ethoxylated and acrylated triethanolamine or ϵ-aminecaprolactam or acrylated block copolymer of ethylene oxide (EO) and propylene oxide (PO) are described. Chemical characterization of films and migration of the plasticizers through the films were monitored with electron spectroscopy for chemical analysis. The (EO)_x(PO)_y(EO)_x–3A film was shown to be unique in the sense that it efficiently prevents migration of hydrophobic species. © 1997 John Wiley & Sons, Ltd.     

Low-temperature heterogeneous oxidation of sulfide ions on a higher Co oxide system in aqueous medium

Low-temperature heterogenous oxidation of sulfide ions on a higher Co oxide system in aqueous medium has been studied. The effects of pH, temperature and catalyst amount on the kinetic parameters as well as on the selectivity of the oxidation process were investigated. An oxidation mechanism has been proposed based on the results of kinetic investigations and on the data obtained by IR and XPS spectroscopic studies of Co oxide before and after sulfide ion oxidation.