Phosphorimetric determination of polynuclear aromatic hydrocarbons in gasoline

The possibility of determining pyrene, anthracene, and fluorene in gasoline by phosphorimetry at room temperature after the micellar extraction with sodium dodecyl sulfate was examined. It was found that the above polynuclear aromatic hydrocarbons simultaneously present in gasoline can be selectively determined by room-temperature phosphorimetry using different techniques for the excitation and population of the triplet states of luminophore (stationary and pulse excitation and triplet energy transfer). The proposed procedure was verified by gas chromatography with a mass-selective detector.     

Palladium-containing composite nanomaterials based on polycaprolactam: Formation and structure

Novel Pd(0) nanocomposites using polycaprolactam as a reducing and stabilizing matrix are synthesized. Data on the nanoparticle formation mechanism in a polycaprolactam matrix under the conditions of changing pH of the medium and reagent concentration ratios are obtained. The nanocomposite structure is studied by electron and infrared spectroscopy, X-ray diffraction analysis, atomic force and transmission electron microscopy. The size of metal-containing particles in the composite composition and their size distribution are determined. The obtained nanocomposites can serve as heterogeneous catalysts.     

The importance of glyceraldehyde radiolysis in chemical evolution

Studies in chemical evolution are intended to demonstrate how compounds of biological importance are generated from substances that could have been found in abiotic conditions on the primitive Earth or in extraterrestrial environments. In this context, the aim of the present work was to examine the behavior of dl-glyceraldehyde in both aqueous solution and solid samples under gamma irradiation. We irradiated dl-glyceraldehyde at different doses and temperatures with a gamma source; even at low doses and temperature (77 K), free radicals were detected. Among the products formed were ethylene glycol and glycolaldehyde. Some sugar-like compounds were also detected.

     

Activation of molecular oxygen in trifluoroacetic acid

The interaction of molecular oxygen with aqueous trifluoroacetic acid (TFA) led to an increase in pH. This effect was explained by a decrease in the concentration of the protonated CF₃CO₂H₂⁺ and H₃O⁺ species after oxygen was fed in the reactor. Quantum-chemical calculations show that a radical pair can be formed in an activation-free exothermal reaction involving the radical residue of the acid, the CF₃CO₂H₂⁺...³O₂...CF₃CO₂⁻ peroxide radical, and the acid molecule in the CF₃C₂^·...HOO^· collision complex. It was assumed that the activation of molecular oxygen in aqueous TFA solutions, providing the activity of the system in oxidations of various organic and inorganic substrates, is related to the formation of peroxide radicals in them.     

Fixation of micelle structure by monomer polymerization: Hydrodynamic properties of polymerized micelles

Polymerized and nonpolymerized micelles of N-acryloyl-11-aminoundecanoic acid and its sodium salt in water and dimethylformamide are studied by viscometry, isothermal diffusion, and dynamic light scattering. It is revealed that the hydrodynamic sizes of polymerized micelles (PMs) obtained via polymerization of the surfactants in aqueous solutions at low concentrations of the latter are significantly larger than those of the starting surfactant micelles. In dimethylformamide, as the surfactant concentration at which the synthesis is carried out is increased, the hydrodynamic size of PMs, which is calculated in terms of the cylindrical particle model, rises from 25 to 220 nm. The formation of additional internal crosslinks reduces the equilibrium rigidity of the PM chains by a factor of 1.5–2.     

Self-organization of sulfopolystyrene ionomers with ionic SO<Subscript>3</Subscript>Li groups in carbon tetrachloride

Association of short-chain sulfopolystyrene ionomers containing 5.2 mol % ionic SO₃Li groups in carbon tetrachloride was studied by cold neutron scattering.     

Surfactant properties of alternating amphiphilic copolymers of N-vinylpyrrolidone and 1,1,1,3,3,3-hexafluoroisopropyl α-fluoroacrylate

The colloidal-chemical properties of alternating copolymers of N-vinylpyrrolidone with 1,1,1,3,3,3-hexafluoroisopropyl α-fluoroacrylate were studied by the method of Langmuir film balance.