Mechanism of OH radical-induced oxidation of <Emphasis Type="Italic">p</Emphasis>-cresol to <Emphasis Type="Italic">p</Emphasis>-methylphenoxyl radical

The OH radical-induced oxidation of p-cresol to p-methylphenoxyl radical was studied in aqueous solution in a wide pH range by means of pulse radiolysis combined with optical spectroscopy. OH-adduct cyclohexadienyl type radicals were identified as intermediates of the reaction. In the acidic pH range the first-order rate coefficient of phenoxyl radical formation was found linearly dependent on the H₃O⁺ concentration yielding a bimolecular rate coefficient of 1.8 × 10⁸ mol^–1 dm³ s^–1. In the alkaline range a linear dependence was found on the OH^– concentration with rate coefficient of 4.9 × 10¹⁰ mol^–1 dm³ s^–1. These findings were interpreted in terms of acid-base catalysis of the H₂O elimination from the OH-adduct. With the time resolution applied, 30 ns, the radical cation p-CH₃C₆H₄OH^+. was not observed as intermediate.     

Reductive Acylamination of Pyridine <Emphasis Type="Italic">N</Emphasis>-Oxide with Aminopyridines and Their <Emphasis Type="Italic">N</Emphasis>-<Emphasis Type="Italic">p</Emphasis>-Tolylsulfonyl Derivatives

Pyridine N-oxide reacts with 2- and 3-aminopyridines and their N-p-tolylsulfonyl derivatives in alkaline medium in the presence of p-toluenesulfonyl chloride to give N-p-tolylsulfonyl-2,2′- and 2,3′-dipyridylamines, respectively, as a result of reductive acylamination. In the reactions with 4-aminopyridine and 4-p-tolylsulfonyl-aminopyridine, their N-p-tolylsulfonyl- and N,N-bis(p-tolylsulfonyl) derivatives are formed, while reductive acylamination does not occur.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 1, 2005, pp. 128–130.Original Russian Text Copyright © 2005 by Solekhova, Kurbatov.     

Reaction sites of <Emphasis Type="Italic">N,N′</Emphasis>-substituted <Emphasis Type="Italic">p</Emphasis>-phenylenediamine antioxidants

The geometries of N,N′-diphenylbenzene-1,4-diamine (DPPD), N-phenyl-N′-(1-phenylethyl)benzene-1,4-diamine (SPPD), N-(4-methylpentan-2-yl)-N′-phenylbenzene-1,4-diamine (6PPD), N-propan-2-yl-N′-phenylbenzene-1,4-diamine (IPPD), N-(2-methoxybenzyl)-N′-phenylbenzene-1,4-diamine (MBPPD), and N-phenyl-N′-(2-phenylpropan-2-yl)benzene-1,4-diamine (CPPD) as well as of their dehydrogenation products were optimized by the semiempirical AM1 method. The results support the idea of stable N_B=C_X structures formation during the consecutive dehydrogenation of SPPD, 6PPD, IPPD, and MBPPD antioxidants. The biradicals formed during the second step of dehydrogenation of substituted phenylenediamines might be important for their antioxidant effectiveness. Dedicated to Professor Vladimír Kvasnička, DrSc., in honour of his 65th birthday     

A Study on the Photochemical Transformations of <Emphasis Type="Italic">p</Emphasis>- and <Emphasis Type="Italic">m</Emphasis>-Nitrosonitrobenzenes

Photochemical oxidation of p- and m-nitrosonitrobenzenes to corresponding dinitrobenzenes was studied. The reaction was described by a scheme involving two successive steps, with the rates of photochemical decomposition of isomeric nitrosonitrobenzenes being much higher than those of dinitrobenzenes. Oligomeric azo and azoxy compounds and the products of hydroxylation of the reaction medium were found as final products of the reaction upon long-term irradiation with UV light.__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 4, 2005, pp. 287–292.Original Russian Text Copyright © 2005 by Zelentsov, Logunov.     

Spectrophotometric determination of hemoglobin with <Emphasis Type="Italic">p</Emphasis>-acetylarsenazo

In a Britton-Robinson buffer medium at pH 2.87, hemoglobin can form a color compound with p-acetylarsenazo in the presence of emulgent OP. The maximum absorption locates at 370 nm. The apparent molar absorptivity ɛ_{370 nm} is 4.11 × 10⁵ L/(mol cm). Beer’s law is obeyed over the range of 20–60 mg/L for hemoglobin. After the addition of a suitable amount of emulgent OP, the sensitivity and stability of the system can be obviously enhanced. Ethanol can increase the sensitivity of the system. Sodium chloride can enhance the sensitivity of the color system by 30%. The method has been applied to the determination of total proteins in human serums with satisfactory results. The text was submitted by the authors in English.     

Structural analysis of <Emphasis Type="Italic">w</Emphasis>/<Emphasis Type="Italic">o</Emphasis>/<Emphasis Type="Italic">w</Emphasis> multiple emulsions by means of DSC

Summary The properties of the inner and the external aqueous phases, were studied in w/o/w multiple emulsions with light microscopic image analysis and differential scanning calorimetry (DSC). The importance of multiple emulsions lies in the presence of these aqueous phases, making them available for sustained, controlled drug delivery systems. Differentiation of these two aqueous phases, studying the effect of manufacturing technology on droplet structure, quantitative determination of phase volumes and any changes occurring during storage are essential when planning w/o/w emulsions. The present study uses microscopic observations combined with DSC measurements in order to identify the formed structure, at developmental stage in case of different components, preparation methods, and stirring rates. These tools are beneficial during manufacturing as in process controls, or to ensure product quality.     

<Emphasis Type="Italic">Ab initio</Emphasis> study of aniline and <Emphasis Type="Italic">n</Emphasis>-propylamine associates with nitrobenzene and <Emphasis Type="Italic">m</Emphasis>-cresol

An ab initio (6-31G**) study of binary associates of aniline and n-propylamine with nitrobenzene and m-cresol has been carried out. The structures corresponding to the total energy minimum of the system have been found for the associates, and their geometrical and energy characteristics have been determined. Basic types of intermolecular interactions have been established, and their effects on the reactivity of the amino group have been investigated.Original Russian Text Copyright © 2004 by I. A. Novakov, V. V. Korolkov, A. I. Pavlyuchko, B. S. Orlinson, and L. A. GribovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 595–601, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Study on Inclusion Complex Formation of <Emphasis Type="Italic">m</Emphasis>-Aminobenzoic Acid with Native and Substituted <Emphasis Type="Italic">β</Emphasis>-Cyclodextrins

The complex formation of native and substituted β-cyclodextrins with m-aminobenzoic acid in water was characterized by calorimetry, ¹H NMR and UV spectroscopic studies. These studies showed that β-, hydroxypropyl-β- and methyl-β-cyclodextrins form 1:1 inclusion complexes with m-aminobenzoic acid. The thermodynamic properties of complex formation (K,Δ_c G ^o,Δ_c H ^o,Δ_c S ^o) were calculated. It was found that the processes of complexation are mainly favorable entropically. Introduction of hydroxypropyl- and methyl-substituents into the β-CD molecule results in negligible enhancement of stability of the complexes formed. The structure of these substituents has no influence on the stability constant values. The insertion of the carboxylic group of m-aminobenzoic acid into the cyclodextrin cavity was confirmed by ¹H NMR data.     

Stereochemical Features of the Condensation of Lithiated (<Emphasis Type="Italic">S</Emphasis>)-<Emphasis Type="Italic">N,N</Emphasis>-Dimethyl-1-phenylethylamine with <Emphasis Type="Italic">o</Emphasis>-Methoxybenzophenones

The condensation of lithiated (S)-N,N-dimethyl-1-phenylethylamine with o-methoxybenzophenones occurs in a nonstereoselective fashion due to possible coordination of lithium not only at the carbonyl group but also at the oxygen atom of the ortho-methoxy group.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 4, 2005, pp. 567–570.Original Russian Text Copyright © 2005 by Dem’yanovich, Shishkina, Gritsyuk, Potekhin, Chesnova, Ashkinadze.     

Radical copolymerization of acrylic acid with derivatives of monoethanolamine vinyl ether and <Emphasis Type="Italic">o</Emphasis>- and <Emphasis Type="Italic">p</Emphasis>-chloranil

Radical copolymerization of derivatives of monoethanolamine vinyl ether and o- and p-chloranil with acrylic acid was studied. The parameter p for this system was determined by the Shtraikhman analytical graphic method; the copolymerization constants, Alfrey-Price specific activity and polarity parameters, probabilities of formation of various unit sequences in the macromolecular chain, lengths of sequences of similar monomeric units, and Harwood block structure parameters were calculated.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 10, 2004, pp. 1689–1692.Original Russian Text Copyright © 2004 by Nikitina, Zhunusova, Shoinbekova, Mukhitdinova, Ergozhin.     

Synthesis of 4-[(1<Emphasis Type="Italic">R</Emphasis>,4<Emphasis Type="Italic">R</Emphasis>)-3-Oxo-<Emphasis Type="Italic">p</Emphasis>-menthan-2-ylidenemethyl]benzoic Acid and Its Esters

Carbonylation of (E)-2-(4-halobenzylidene)-p-menthan-3-ones, catalyzed by PdCl₂(PPh₃)₂, gave a distereometric mixure of 4-[(1R,4R)- and (1R,4S)-3-oxo-p-menthan-2-ylidenemethyl]benzoic acids, whose reaction with phenols gave 1R,4R diastereomers of the corresponding esters.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 659–664.Original Russian Text Copyright © 2005 by Drushlyak, Kutulya, Pivnenko, Vashchenko.     

Synthesis from geraniol of (2<Emphasis Type="Italic">E</Emphasis>,6<Emphasis Type="Italic">E</Emphasis>,10<Emphasis Type="Italic">E</Emphasis>,14<Emphasis Type="Italic">E</Emphasis>)-16-hydroxygeranylgeraniol and some of its derivatives

Several α,ω-bifunctional derivatives of E,E,E-geranylgeraniol were prepared via convergent synthesis starting with geraniol (8), which was converted in three steps into the tetrahydropyranyl ether of 8-chlorogeraniol (9) and 8-hydroxygeranylphenylsulfone (10). Combination of synthons 9 and 10 with subsequent reductive removal of the phenylsulfonyl group produced the tetrahydropyranyl ether of ω-hydroxygeranylgeraniol (5), hydrolysis of which gave exclusively trans-ω-hydroxygeranylgeraniol (1). Derivatives 5–7 of geranylgeraniol were synthesized using standard methods. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 231–234, May–June, 2007.     

Excess molar enthalpy of binary mixtures of hexane+ethyl benzene, <Emphasis Type="Italic">o</Emphasis>-xylene, <Emphasis Type="Italic">m</Emphasis>-xylene and <Emphasis Type="Italic">p</Emphasis>-xylene at 298.15 K

Summary This paper reports excess molar enthalpies of the binary systems hexane+ethyl benzene, hexane+o-xylene, hexane+m-xylene and hexane+p-xylene at 298.15 K and atmospheric pressure, over the whole composition range. The data was measured directly using a Calvet microcalorimeter. The excess magnitude was correlated to a Redlich-Kister type equation for each mixture. Also, we will discuss the results for the four mixtures studied here and by comparison with the same binary systems but containing propyl propanoate as first component. Finally, we will correlate our results with the Nitta-Chao and the three UNIFAC theoretical approximations.     

Reactions of <Emphasis Type="Italic">N</Emphasis>-alkyl- and <Emphasis Type="Italic">N</Emphasis>-aryltrihalogenoacetamides with phosphorus pentachloride

In the study of reactions of N-alkyl- and N-aryltrihalogenoacetamides with PCl₅, it was demonstrated for the first time that 3-alkyl(aryl)-2,2,2,4 tetrachloro-4-trihalomethyl-1,3,2-λ⁵-oxazaphosphetanes are intermediates in the synthesis of trihaloacetimidoyl chlorides. According to quantum-chemical calculations, acyclic N-tetrachlorophosphoranes, which are the primary products in the reactions of trihaloacetamides with PCl⁵, undergo rapid cyclization into the corresponding phosphorates and subsequent 1,3-chlorotropic migration gives rise to oxazaphosphetanes with the five-coordinate P atom.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 739-744, March, 2005.