Classical Benzotriazole‐Mediated α‐Aminoalkylations of Alkynes: Synthesis and Characterization of Alk‐2‐yn‐1‐amines as Amphiphilic Materials

Reactions of readily available and stable benzotriazolemethanamines 1a – l , obtained from aldehydes and secondary amines (Scheme 2), gave the expected alk‐2‐yn‐1‐amines 3a – t (Scheme 3). The amphiphilic character of the synthesized products was responsible for physicochemical measurements. Specific aggregation properties of the obtained compounds make them useful as electroactive materials in the Langmuir–Blodgett technique.     

Exact solution of a degenerate fully nonlinear diffusion equation

An exact solution is given for the evolution of an initially v-shaped surface by a fully nonlinear diffusion equation. This is the unique generalized solution that is continuous but not twice differentiable. Since the profile velocity decreases faster than the reciprocal of the profile curvature, the point of infinite curvature persists for a finite positive time.     

Effects of Silver Island Films on the Luminescent Intensity and Decay Times of Lanthanide Chelates

We examined the emission intensity and decay times of chelates Tb³⁺ and Eu³⁺ in micron thick samples between films of sub-wavelength size silver particles. We observed modest increases in emission intensities for the complexes between the silver particles as compared to between unsilvered quartz plates. The intensity decay times were dramatically decreased by the silver particles, which was in part mediated by diffusion toward the silver particles. These results indicated that luminescent lanthanides in close proximity to silver particles display increased rates of radiative decay. The use of luminophore-metallic surface interactions provides new opportunities for creation of luminescent probes with novel spectral properties.     

Iodine-catalyzed allylic alkylation of sulfonamides and carbamates with allylic alcohols at room temperature

A highly efficient iodine-catalyzed allylic alkylation of a wide variety of sulfonamides and carbamates with allylic alcohols is reported herein. The reaction is operationally straightforward and proceeds under very mild conditions at room temperature in good to excellent yields (up to 99%).     

Synthesis and Structural Characterisation of Derivatives of Tricyclo[5.2.1.02,6]Dec‐8‐Ene‐3,5‐Dione with an Expected Antimicrobial Activity

Anhydrides, imides, N‐ethylimides, N‐hydroxyimides and N‐aminoimides of 1,4,5,6‐tetramethyl‐bicyclo[5.2.1.0^2,6]hept‐5‐ene‐2,3‐dicarboxylic acid, 1,4,5,6,7‐pentamethyl‐bicyclo[5.2.1.0^2,6]hept‐5‐ene‐2,3‐dicarboxylic acid and 7‐ethyl‐1,4,5,6‐tetramethyl‐bicyclo[5.2.1.0^2,6]hept‐5‐ene‐2,3‐dicarboxylic acid were obtained. Antimicrobial activity of the newly obtained derivatives was tested against selected Gram‐positive and Gram‐negative bacteria and fungi of the Candida species. The structures of obtained compounds and their antimicrobial activity were compared. Structure of 1b, 2b and 1e were determined by an X‐ray analysis.     

Removal and enrichment of copper ions from aqueous solution by 1,8-diaminonapthalene polymer

Microparticles of poly(1,8-diaminonapthalene) (PDAN) were prepared by chemically oxidative polymerization by (NH₄)₂S₂O₈. The effect of pH on the sorption of Cd(II), Cu(II), Ni(II), Mn(II), Zn(II) and Pb(II) on PDAN was examined by the batch procedure. PDAN showed good sorption capacity and high selectivity towards Cu(II) in comparison with the very popular chelating sorbent Chelex 100 containing iminodiacetic functional groups. The on-line preconcentration system containing the knotted reactor with the obtained polymer was examined for the sorption and desorption processes of copper ions. The applicability of this system was checked by analysis of Cu(II) content in standard reference material (NIST 1643e) and some natural water samples.     

Apparent molar volumes, expansibilities, and isentropic compressibilities of selected electrolytes in methanol

Densities of solutions of sodium bromide, sodium perchlorate, sodium tetraphenylborate, and tetraphenylphosphonium bromide in methanol at the temperatures ranging from 283.15 to 313.15 K have been measured. Ultrasound velocities for the above systems at T = 298.15 K have been determined. From the obtained data, the partial molar volumes and the partial molar isentropic compressibilities for electrolytes in solution have been estimated. Division into the ionic contributions has been proposed on the basis of the reference electrolyte method. The existence of the high-volume intermediate shell with an enhanced structure has been suggested.     

Selective methane oxidation to formaldehyde using polymorphic T-, M-, and H-forms of niobium(V) oxide as catalysts

The investigations of selective methane oxidation to formaldehyde over T-Nb₂O₅, the mixture of M-Nb₂O₅ and H-Nb₂O₅ as well as H-Nb₂O₅ were carried out. The tests were conducted under atmospheric pressure, in the temperature range 420–750°C, using oxygen as the oxidizing agent. T-Nb₂O₅ samples were examined at the contact time 0.7–1.8 s (GHSV 2000–5143 h⁻¹). Other polymorphic forms of niobium(V) oxide were examined at the contact time 0.9 s. Various polymorphic forms of Nb₂O₅ displayed various formaldehyde and carbon dioxide yield. Using H-Nb₂O₅ and M-Nb₂O₅ phases with a block type structure, made it possible to obtain higher formaldehyde selectivity (78 % at 0.9 s) as compared to T-Nb₂O₅ (47 % at 0.9 s), a polymorphic form which does not have a block type structure. However, the highest space time yield of formaldehyde (46 g per kg of catalyst per h) was obtained over T-Nb₂O₅ supported on SiO₂. Presented at the 34th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 21–25 May 2007.     

Synthesis and biological activity of novel benzoazoles,benzoazines and other analogs functionalized by 2,4-dihydroxyphenyl moiety

Research on Chemical Intermediates - Novel benzoazoles, benzoazines, benzothiazoles, benzothiazines and other related compounds possessing a 2,4-dihydroxyphenyl moiety were prepared. The compounds...