Effect of maltodextrins on the surface activity of small-molecule surfactants

We report on the effect of commercially important polysaccharides (maltodextrins with variable dextrose equivalent (Paselli SA-2, MD-6 and MD-10) on the surface activity at the air–water interface of small-molecule surfactants (sms), possessing different hydrophobic–lipophilic balance ((SSL (Na⁺), the main component is a sodium salt of stearol–lactoyl lactic acid, and PGE (080), polyglycerol ester of C18 fatty acid), and widely used in food products. A marked change of the surface activity of sms was found in the presence of maltodextrins by tensiometry. The combined data of laser multiangle light scattering and mixing calorimetry have suggested that this result is governed by specific complex formation between maltodextrins and sms in aqueous medium. Measurements have been made of the molar mass, the second virial coefficient and the enthalpy of intermolecular interactions in aqueous solutions. The implication of a degree of polymerization of maltodextrins in this phenomenon was shown. The interrelation between the molecular parameters of the formed complexes and their surface activity at the air–water interface has been revealed and discussed.     

Synthesis and properties of novel dialkylaminocarbenium salts

Novel dialkylaminocarbenium salts with metallocomplex counter ions were prepared by the reaction of phosgene with either DMF or tetramethylurea in the presence of metal chlorides. Reactions of organosilicon amides with phosgene gave corresponding carbenium salts, while organosilicon ureas yielded aminoiminocarbenium salts. Dialkylaminochlorocarbenium salts were reduced with hydrosilanes to give dialkylaminocarbenium, salts and can be easily hydrolyzed to afford either amides or ureas. Pathways of the reaction with water and alcohols depend on the nature of reagent and the reaction conditions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1035–1040, May 1997.     

Behavior of protein-like N-vinylcaprolactam and N-vinylimidazole copolymers in aqueous solutions

The free-radical copolymerization of N-vinylcaprolactam and N-vinylimidazole (at an initial comonomer ratio of 85: 15, mol/mol) initiated by a persulfate-tertiary amine redox system in 10% aqueous DMSO at 25 and 65°C (at temperatures below and above the temperature of phase separation in the reaction system, respectively) yielded macromolecular products that were subsequently separated into thermally precipitating and nonprecipitating fractions. Investigations of these fractions by capillary viscometry, static and dynamic laser light scattering, and high-sensitivity DSC showed that macromolecules of both types of copolymers are strongly associated in aqueous solutions. Upon heating of solutions of thermally nonprecipitating fractions, additional aggregation takes place and this phenomenon is accompanied by a decrease in the size of particles without loss in their solubility until at least 70°C is reached. As for the set of properties exhibited in aqueous solutions, the thermally nonprecipitating fraction of the copolymer synthesized at 65°C may be assigned to protein-like macromolecules.     

Liquid chromatography of benzene derivatives on a porous methacrylate copolymer containing epoxy groups

Summary The retention of benzene derivatives with nonpolar and polar substituents on a porous methacrylate copolymer containing epoxy groups using both nonpolar and polar eluents was investigated. When n-hexane is used as the eluent, the retention of n-alkylbenzenes and polymethylbenzenes is weaker than that of benzene. In the case of benzene derivatives containing polar functional groups their capacity ratios (k) on this porous polymer increases approximately linearly with the increase of the adsorbate molecules dipole moment. The retention characteristics of the methacrylate copolymer were compared with that of a styrene-divinylbenzene copolymer and silica gels with a hydroxylated surface and with a surface modified by chemically bonded alkylsilyl groups.     

Heterocyclic compounds from 3-(4-phenyl) benzoyl propionic acid

3-(4-Phenyl) benzoyl propionic acid was used as the starting material for the synthesisof furanones (2), pyrrolinones (5), pyridazinones (7), benzoxazinones (8) and quinazolinones (9-11). The behaviour of the derivatives of furanones and benzoxazinones toward different nucleophiles is reported.     

Structure of surface compounds formed during chemisorption of BBr3 on dehydrated Aerosil

The chemisorption of boron bromide on the surface of Aerosil calcined at 870 K in vacuo was studied by IR spectroscopy combined with chemical and gravimetric analysis. It was determined that the chemical reaction of structural silanol groups with BBr₃ vapor occurs monofunctionally with the formation of SiOBBr₂ groups. This indicates uniform distribution of isolated silanol groups on the surface of dehydrated Aerosils.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 3, pp. 374–377, May–June, 1989.     

Oxygen-containing organosilicas: Synthesis and properties

Organosilicas with grafted -diketone derivatives were synthesized and investigated by IR-spectroscopy and chemical analysis. The conditions of strontium ion uptake on oxygen-containing organosilicas were studied. Heterogeneous Pt-complex catalyst for liquid phase hydrosililation based on acetylacetone bonded to silica was obtained.     

Luminescent-probe study of the structure of alcohol — Water solutions

Journal of Structural Chemistry -     

Influence of vanadium doping on the behavior of YBa_2Cu_3O_7-y

YBa2Cu3-xVxO7-y(x=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) superconductors have been prepared. X-ray diffraction shows that the system remains orthorhombic for all compositions studied, but for x > 0.4 V2O5 was detected as an impurity phase. Substitution of V5+ for Cu2+ occurs in the Cu(2) sites on the Cu(2)-O planes. The introduction of the high valence element, vanadium, produces the extra free-electrons. These electrons recombine with the positive carrier of the system. It makes depression of the mobility and the Hall number of YBa2Cu3-xVxO7-v and also results in a depression of TC.