L-(-)-Menthol in the Synthesis of Key Synthons for Optically Active Methyl-Branched Insect Pheromones

A synthesis of optically active 4S-methylhexanal, 1-bromo-3S-methylheptane, and 1-bromo-3S-methylundecane, which are key synthons for several methyl-branched insect pheromones, that is based on chemically selective transformations of 6-tosyloxy- and 6-iodoisopropyl-4R-methylhexanoates that are available from L-(-)-menthol was proposed. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 592–593, November–December, 2005.     

Anodic behavior of Zn5Al and Zn55Al alloys alloyed with calcium in NaCl solutions

Results of a study of the anodic behavior of Zn5Al and Zn55Al alloys alloyed with calcium in a NaCl electrolyte are presented.     

Acid-catalyzed rearrangement of 3-(β-2-aminostyryl)quinoxalin-2(1H)ones—a new and efficient method for the synthesis of 2-benzimidazol-2-ylquinolines

A highly efficient, one-step, versatile method for the synthesis of 2-benzimidazol-2-ylquinolines has been developed on the basis of an acid-catalyzed rearrangement proceeding via a novel ring contraction of 3-(β-2-aminostyryl)quinoxalin-2(1H)ones.     

Oxidation of phenols with chlorine dioxide

The oxidation of different phenols, viz., phenol, 3-methylphenol, 4-methylphenol, 4-tert-butylphenol, 2-cyclohexylphenol, 2,6-di-tert-butyl-4-methylphenol, and 2,4-dichlorophenol, with chlorine dioxide in acetonitrile was studied spectrophotometrically. The reaction rate is described by a second-order equation w = k[PhOH]· [ClO₂]. The rate constants were measured and activation parameters of oxidation were determined in a temperature interval of 10–60°C. A dependence of the reaction rate constant on the phenol structure was found. The oxidation products were identified, and their yields were established.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2184–2187, October, 2004.     

Influence of Sodium Dodecyl Sulfate on the Protolytic Properties of N,N-Dimethyl-N′-(2-hydroxybenzyl) Ethylenediamine and Its Complexation with Copper(II)

To investigate the effect of sodium dodecyl sulfate (concentration C _s = 5 and 10 mM) on the acid–base properties of N,N-dimethyl-N-(2-hydroxybenzyl) ethylenediamine and its complexation with copper(II) (C _s = 10 mM) was studied using the methods of potentiometry, spectrophotometry (at 298 K), and mathematical simulation of equilibria in solutions. The sodium dodecyl sulfate contributes to the formation of a monomeric form of N,N-dimethyl-N-(2-hydroxybenzyl)ethylenediamine, while this compound exists in 40% isopropyl alcohol predominantly in the form of a dimer. The acidic properties of protonated monomeric and dimeric species are weaker than those in an aqueous alcohol solution. Sodium dodecyl sulfate facilitates the coordination of the deprotonated form of ligand. The region of the predominant accumulation of an uncharged complex of 1 : 2 composition is shifted to lower pH values (11.0 and 7.5, respectively), whereas the molar absorption coefficient of the complex increases by approximately 1.7 times. The apparent stability constants of complexes of the same type increase.     

Reaction of N,N-Dimethyl-N′-(2-hydroxybenzyl)ethylenediamine with Copper(II) in the Presence of Surfactants

The protolytic properties of N,N-dimethyl-N′-(2-hydroxybenzyl) ethylenediamine (HL) and its complexation with copper(II) in the presence of cationic (cetyltrimethylammonium bromide) and nonionic (Triton X-100) surfactants were studied by pH-metry, spectrophotometry, and mathematical simulation of the equilibria. Cetyltrimethylammonium bromide affects the H₂L₂ ⇄ 2HL equilibrium. Along with the protonated monomeric and dimeric species, triprotonated tetrameric species were revealed in surfactant solutions, as in aqueous solutions of isopropyl alcohol. The surfactants affect the complexation of HL with Cu(II). The 1 : 2 complex with the phenolate form in solutions of cetyltrimethylammonium bromide is formed in a more acidic medium (pH ∼5.5) compared to an aqueous solution of isopropyl alcohol (pH ∼11). The apparent stability constants of the complexes increase in the presence of surfactants, especially of cetyltrimethylammonium bromide.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 3, 2005, pp. 379–382.Original Russian Text Copyright © 2005 by Sal’nikov, Boos, Ryzhkina, Ganieva.     

Synthesis of Optically Pure 3<Emphasis Type="Italic">R</Emphasis>-methylcyclopentan-1-one from L-(-)-menthol

Synthesis of optically pure 3R-methylcyclopentan-1-one using in the key step Dieckmann cyclization of diisopropyl 3R-methylhexan-1,6-dioate, which is accessible from L-(-)-menthol, was proposed. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 448–450, September–October, 2005.     

Oxidation of alcohols by chlorine dioxide in organic solvents

The kinetics of oxidation of a series of alcohols (propan-2-ol, 2-methylpropan-1-ol, butan-1-ol, butan-2-ol, 3-methylpentan-1-ol, heptan-4-ol, decan-2-ol, cyclohexanol, borneol) by chlorine dioxide in organic solvents was studied using spectrophotometry. The reaction is described by the second-order rate equation w = k[ROH][ClO₂]. The rate constants were measured in the range of 10–60 °C, and the activation parameters of the processes were calculated. The products were identified, and the yields were determined.     

Identification of Phenomenological Superplasticity Models Based on the Results of Technological Experiments

A general scheme for identifying the constitutive equations of superplasticity, according to which the values of material constants are calculated by the results of technological experiments using interpretation techniques based on the adoption of additional hypotheses of the stress-strain state nature in the deformation region, is proposed. The verification of the result is carried out by comparing the experimental data with the corresponding solutions of the boundary problems for superplasticity mechanics obtained using software complexes such as ANSYS and ABAQUS. The obtained result is used as input data for a program, and the solution of the boundary value problem is found without additional hypotheses of the stress-strain state nature. The practical application of the proposed approach for the standard power model of superplasticity shows that the accuracy of the forming duration simulation is no less than 4%.     

Sorption of organic molecules on surfaces of a microporous polymer adsorbent modified with different quantities of uracil

The sorption of organic molecules on the surfaces of a number of adsorbents based on a microporous copolymer of styrene and divinylbenzene modified with different quantities of uracil is studied by means of inverse gas chromatography at infinite dilution. Samples containing 10^–6, 10^–5, 10^–4, 10^–3, 10^–2, and 0.5 × 10^?1 weight parts of uracil (the рС of uracil ranges from 1.3 to 6) are studied. The contributions from different intermolecular interactions to the Helmholtz energy of sorption are calculated via the linear free energy relationship. It is found that as the concentration of uracil on the surface of the polymer adsorbent grows, the contributions from different intermolecular interactions and the conventional polarity of the surface have a bend at рС = 3, due probably to the formation of a supramolecular structure of uracil. Based on the obtained results, it is concluded that the formation of the supramolecular structure of uracil on the surface of the polymer adsorbent starts when рС < 3.