Synthesis and ring-chain isomerism of acid chlorides and amides of 2-(2-pyridyl and 2-quinolylcarbonyl) benzoic acids

The reaction of 2-(2 pyridytcarbonyl)benzoic acid with thionyl chloride affords an unexpected product of the intramolecular acylation of the pyridine nitrogen atom, namely, 6,11-dioxo-6,11-dihydrobenzo[blquinotizinium chloride. At the same time, 2-(2-quinotylcarbonyl)benzoic acid forms the expected cyclic acid chloride, namely, 3-(2-gitinotyl)-3-chlorophthalide in this reaction. Both compounds acylate ammonia and primary amines, including those with bulky alkyl groups (tert-butyl, 1-adamantyl, and 1,1,3,3-tetramethylbutyl) with the formation of 2-R-3-hydroxy-3-(2pyridyl- or 2-quinolyl)isoindolines. The protonation of the pyridine nitrogen atom of N-(1,1,3,3-tetramethylbutyl)-2-(2pyridylcarbonyl)benzamide, obtained in the open amide form, is accompanied by the closing of the isoindotinone ring; the deprotonation is accompanied by ring opening.Riga Technical University, Riga LV-1048. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 499–504, April, 1994. Original article submitted March 17, 1994.     

Static light scattering,ultraviolet–visible,and fluorescence spectroscopy from fluorescent methyl methacrylate/benzazole dye copolymers displaying an intramolecular proton‐transfer mechanism in the electronically excited state

The solution behavior of new copolymers of methyl methacrylate and benzazole dyes emitting fluorescence because of an intramolecular proton‐transfer mechanism in the electronically excited state has been investigated by static light scattering, fluorescence spectroscopy, ultraviolet–visible, and gel permeation chromatography. In the dilute regime, with tetrahydrofuran (THF) and chloroform as solvents, the copolymers behave as typical polydisperse linear chains in good solvents. The analysis of the osmotic modulus for concentrated solutions in THF (c ≥ 60 g L^?1) indicates the existence of an interchain association mechanism. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 341–350, 2003     

N-dealkylation of 2-(tert-butyl)-3-hydroxy-3-(4-chlorophenyl)isoindolinone and n-(tert-alkyl)-2-aroylbenzamides in concentrated sulfuric acid

It has been established that 2-(tert-butyl)-3-hydroxy-3-(4-chlorophenyl)isoindolinone and N-(tert-Alkyl)-2-aroylbenzamides are dealkylated in concentrated sulfuric acid to give 3-hydroxy-3-arylisoindolinones. The reaction is realizable. only when there is a tert-alkyl group attached to the nitrogen atom. The reaction mechanism is discussed on the basis of data on the change with time in the electronic spectra of the investigated compounds in concentrated sulfuric acid and a comparison with the spectra of model structures.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 763–765, June, 1977.     

Spectroscopic study of 1-cyanoacetyl-2-alkylhydrazines and their ring isomers — 1-alkyl-5-amino-3-pyrazolones

The structures of 1-cyanoacetyl-2-alkylhydrazines and their ring isomers, viz., 1-alkyl-5-amino-3-pyrazolones, to which they are readily cyclized, were investigated by IR, UV, and PMR spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 516–519, April, 1981.     

Ionisation dynamics at intermediate momentum transfer: an (e, 2e) investigation on argon

Relative triple differential cross section for the coplanar asymmetric (e, 2e) reaction in argon have been measured at 1.5 KeV incident energy and 40 eV ejected electron energy in several kinematics. Depending on the scattering angle, ? _a , the chosen kinematics select either ionising collisions belonging to the Bethe ridge (? _a =9.2°) or processes in the intermediate region between the pure dipolar and binary regimes. The more relevant finding is the presence of a minimum in the recoil lobe, almost opposite to the direction of the momentum transfer. This feature is qualitatively explained by a first Born model, which describes the ejected electron by a Coulomb wave-function. This result suggests that in the investigated kinematics the interaction of the slow ejected electron with the residual ion is the dominant effect beyond the first order electron-electron interactions.     

Volumetric properties of ethanol–water mixtures under high temperatures and pressures

The densities of ethanol and ethanol–water mixtures were measured with a vibrating tube densimeter at 25.0, 50.0 and 75.0 °C in the pressure range from 0.10 to 40.00 MPa. Densities were correlated using an empirical model. Partial molar volumes, excess molar volumes, isothermal compressibilities, cubic expansion coefficients and internal pressures were calculated from obtained densities. This study reports the dependence of densities, partial molar volumes, excess molar volumes, isothermal compressibilities, cubic expansion coefficients and internal pressures on composition, temperature and pressure.     

In vitro ageing and degradation of PEG-PLA diblock copolymer-based nanoparticles

Diblock copolymers composed of poly(oxy-ethylene) (POE) and poly(dl-lactic acid) segments were synthesized by anionic polymerization of d,l-lactide using the oxyanion formed by reaction of the monohydroxyl monomethoxy-poly(ethylene glycol) on sodium hydride. For comparison, a similar copolymer was prepared by using tin octoate to catalyze the lactide polymerization. The copolymers were used to make nanoparticles, which were stored at 4 °C. After a few months under these storage conditions, a dramatic decrease of the poly(ethylene glycol) content was observed, however, the mean diameter of the nanoparticles was not affected. The degradation of the nanoparticles was investigated in vitro under conditions selected to mimic physiological conditions. Changes of characteristics were monitored by ¹H NMR, SEC, DLLS and CZE on nanoparticles and/or on the degradation by-products dissolved in the ageing medium. According to their nanometric dimensions, the microparticles degraded very slowly and there was no difference in behaviour between the sodium hydride and the stannous octoate-derived copolymers.     

Experimental observation of light-induced solitary waves of analyte bands in capillary electrophoresis.

The phenomenon of electrophoresis in free solution has been studied theoretically down to the molecular level for decades. In addition, intermolecular photo-induced proton transfer reactions, which occur in a wide class of molecules (phenols and aminoarenes) as well as proteins (green fluorescent protein), were also studied extensively. However, the study of the effect of light-induced electrophoretic mobility changes of the analytes in electrophoresis was begun only recently. In the present work, capillary zone electrophoresis was chosen as the environment to measure the magnitude of these electrophoretic mobility shifts induced by light. Background electrolytes (running electrolytes) with high refractive indices were developed, allowing the capillary to work like an optical fiber. The experimental conditions for obtaining stable coupling and guided laser light along the liquid core are discussed. Experimental evidence of band compression is observed, leading to a solitary wave behavior of the analyte band (2-naphthol). These solitary waves result from competition between thermal diffusion (dispersion mechanism) and a nonlinear (band compression) effect due to the combined electrophoresis phenomenon and absorption of guided light by the molecules of the band (which are subjected to a "reversible intermolecular proton transfer reaction" as one of their decay routes). The possibilities of applying this effect to different methods and techniques are also discussed.     

Phenol photonitration

This paper presents some new data on nitrophenol formation from phenol under illumination, and reviews the studies performed on phenol photonitration, from its discovery in 1988 to the very recent elucidation of its reaction pathway by the authors. Recent experimental results account for the pH effect on phenol photonitration. The nitrogen sources so far investigated are nitrate and nitrite, which undergo photolysis upon absorption of near-UV light. These studies have given a relevant information on the role of both nitrate and nitrite as environmental factors. Such processes can take place both in natural waters and in atmospheric hydrometeors.     

Satellite structures and momentum distributions in binary (e, 2e) spectroscopy of N2O

The (e, 2e) coincidence technique has been applied in studying the valence shell of N₂O. The assignment of some satellite structures is discussed.