Temperature effect on the microstructure and viscoelastic properties of aqueous micellar systems of sodium <Emphasis Type="Italic">N</Emphasis>-methyl-<Emphasis Type="Italic">N</Emphasis>-oleyl taurate

The quantitative characteristics of the temperature effect on the rheological properties of aqueous solutions of the anionic surfactant sodium methyl oleyl taurate (SMOT) are presented. An increase in the intensity of thermal motion of surfactant molecules on heating from 25 to 45 °С was shown to decrease the average contour length of SMOT micelles from 2 μm to 700 nm. The decrease in the length of cylindrical micelles is probably one of the main reasons for a substantial decrease in the viscosity of micellar solutions of the surfactant with temperature.     

Supramolecular catalytic systems based on 1, 4-diazabicyclo[2.2.2]octane,its alkylated quaternary derivatives,and lanthanum nitrate

Spectrophotometry was used to study the catalytic effects of the systems composed of N-monoand N, N-dialkylated 1, 4-diazabicyclo[2.2.2]octanes and lanthanum nitrate on the hydrolysis rate of O-alkyl O-4-nitrophenyl chloromethylphosphonates (Alk = Et, Buⁿ, and n-hexyl). The mechanism of action and efficiency of the catalytic system depend on the structure of the heterocycle, its propensity to aggregation and complexation with the lanthanum cation, and the relative content of the components in solution. The maximum catalytic effect (a ～115-fold increase in the hydrolysis rate constant) was achieved in micellar solutions of the cationic monoalkylated derivative of 1, 4-diazabicyclo[2.2.2]octane and lanthanum nitrate.

     

Enthalpies of the Diels–Alder reactions of a series of dienes with tetracyanoethylene and 4-phenyl-1,2,4-triazoline-3,5-dione

Russian Chemical Bulletin - The enthalpies of the Diels–Alder reactions of twenty dienes with two active dienophiles, tetracyanoethylene and 4-phenyl-1,2,4-triazoline-3,5-dione, are compared,...     

Synthesis of new types of aminomethylenediphosphorus-containing acids and their derivatives

Convenient methods for synthesis of various aminomethylenediphosphorus-containing acids and their derivatives starting from available trimethylsilyl esters of hypophosphorous and phosphorous acids, ethoxymethyleneimine hydrochlorides, and N-substituted formamides have been proposed. Selected properties of the obtained compounds have been examined.

     

Lead,cadmium, and arsenic in commercial algae of the Sea of Japan

The concentrations of toxic elements (arsenic, cadmium, lead) in commercial algae Saccharina japonica and Ahnfeltia tobuchiensis from different habitats of the Sea of Japan have been determined. Bioaccumulation of heavy metals has been analyzed with respect to the habitat and growth conditions. The lead content of Sascharina japonica from all habitats and arsenic content of the same alga species from the Ol’ga Bay, Kievka Bay, and Tatar Strait have been found to exceed maximum permissible levels. Increased lead concentrations have been detected in Ahnfeltia tobuchiensis. Samples of Ahnfeltia tobuchiensis collected from the bottom layer contain more toxic elements than those from the upper layer.     

Advances in the synthesis of 7-(3-cyclopentyloxy-4-methoxyphenyl)-hexahydro-3<Emphasis Type="Italic">H</Emphasis>-pyrrolizin-3-one (Pyrromilast)–a promising agent for treatment of chronic obstructive pulmonary disease

The review summarizes the known approaches to diastereo- and enantioselective synthesis of 7-(3-cyclopentyloxy-4-methoxyphenyl)hexahydro-3H-pyrrolizin-3-one (Pyrromilast), a highly active inhibitor of subtype 4B phosphodiesterase and a promising agent for treatment of chronic obstructive pulmonary disease.     

Quantum chemical studies of azoles 4. A novel elimination–addition mechanism of tetrazole and 1,2,4-triazole electrophilic substitution

Thermodynamic parameters of the addition–elimination and elimination–addition electrophilic substitution reactions of 1H-tetrazole and 1,2,4-1H-triazole obtained from DFT B3LYP/ 6-31G(d,p) quantum chemical calculations with proton as model electrophile are compared. According to calculations, the elimination–addition reactions can proceed without preliminary formation of N-protonated azolium salts.     

Alkylation of toluene with dichloromethane in the presence of triisobutylaluminum and perfluorophenylborates

¹H NMR method showed that in systems based on triisobutylaluminum (TIBA) and triphenylcyclopropenylium [Ph₃C₃]⁺[B(C₆F₅)₄]–(CPB) or triphenylmethylium [Ph₃C]⁺[B(C₆F₅)₄]–(TB) perfluorophenylborates in a toluene–dichloromethane mixture the Friedel–Crafts process occurs with the formation of ditolylmethane (DTM) accompanied by the complete decomposition of TIBA to form isobutane. ¹⁹F NMR spectroscopy showed that the [B(C₆F₅)₄]–anion decomposes in the systems to form B(C₆F₅)₃ and HC₆F₅. The short-living [AlBu₂ ⁱ]+ cation formed in the reaction of perfluorophenylborates with TIBA is assumed to be the species initiating the process. It has been shown that CPB is less reactive than TB. The addition of a stoichiometric amount of Ph₂CCpFluHfMe₂ exerts no effect on the process with the CPB-containing system but inhibits the reaction in the case of TB.