Degradation processes in the cellulose/<Emphasis Type="Italic">N</Emphasis>-methylmorpholine-<Emphasis Type="Italic">N</Emphasis>-oxide system studied by HPLC and ESR. Radical formation/recombination kinetics under UV photolysis at 77 K

Degradation processes of N-methylmorpholine-N-oxide monohydrate (NMMO), cellulose and cellulose/NMMO solutions were studied by high performance liquid chromatography (HPLC) and electron spin resonance (ESR) spectroscopy. Kinetics of radical accumulation processes under UV (λ = 248 nm) excimer laser flash photolysis was investigated by ESR at 77 K. Beside radical products of cellulose generated and stabilized at low temperature, radicals in NMMO and cellulose/NMMO solutions were studied for the first time in those systems and attributed to nitroxide type radicals ∼CH₂–NO^•–CH₂∼ and/or ∼CH₂–NO^•–CH₃∼ at the first and methyl ^•CH₃ and formyl ^•CHO radicals at the second step of the photo-induced reaction. Kinetic study of radicals revealed that formation and recombination rates of radical reaction depend on cellulose concentration in cellulose/NMMO solutions and additional ingredients, e.g., Fe(II) and propyl gallate. HPLC measurements showed that the concentrations of ring degradation products, e.g., aminoethanol and acetaldehyde, are determined by the composition of the cellulose/NMMO solution. Results based on HPLC are mainly maintained by ESR that supports the assumption concerning a radical initiated ring-opening of NMMO.     

Discoloration of cellulose solutions in <Emphasis Type="Italic">N</Emphasis>-methylmorpholine-<Emphasis Type="Italic">N</Emphasis>-oxide (Lyocell). Part 2: Isolation and identification of chromophores

The Lyocell process is a modern green industrial fiber-making technology, which employs N-methylmorpholine-N-oxide monohydrate (NMMO) to directly dissolve cellulose. One problem in Lyocell processing is the discoloration of the spinning dope due to chemical side reactions. Two different methods were elaborated to isolate chromophores, which are present in minute amounts only, from Lyocell fibers, the first one using hydrogen chloride in alcoholic solution, the second one employing boron trifluoride – acetic acid complex. Several chromophores were unambiguously identified by a combination of analytical techniques and comparison to authentic samples. Carbohydrate condensation products, such as catechols, were shown to dominate in early phases of chromophore formation. In later stages, these initial chromophores undergo further condensation reactions with degradation products of NMMO and NMMO itself, leading to nitrogen-containing heterocycles and quinoid products, among others. The incorporation of nitrogen into the chromophores and thus the participation of the solvent in chromophore formation were proven.     

Solutions of cellulose and its blends with synthetic polymers in <Emphasis Type="Italic">N</Emphasis>-methylmorpholine-<Emphasis Type="Italic">N</Emphasis>-oxide: Preparation,phase state,structure, and properties

Highly concentrated solutions of cellulose and solutions of cellulose blends with synthetic polymers are prepared via the solid-phase dissolution of cellulose in N-methylmorpholine-N-oxide. The phase state and morphological features of these solutions are studied via DSC and polarization microscopy, and their rheological behavior is considered. Evolution in the structure of cellulose in these systems is investigated at all stages during spinning of oriented fibers from solutions. It is first shown that the addition of synthetic polymers to cellulose makes it possible to control processes of cellulose structuring; to stop them at the stage of mesophase formation; and, thus, to avoid further perfection of the structure and formation of the crystalline phase of cellulose.     

Homogeneous alkalization of cellulose in <Emphasis Type="Italic">N</Emphasis>-methylmorpholine-<Emphasis Type="Italic">N</Emphasis>-oxide/water solution

Alkali cellulose is an important intermediate in the production of cellulose derivatives. N-methylmorpholine-N-oxide (NMMO)/H₂O was used as a homogeneous reaction medium for the cellulose alkalization process to intensify the alkalization degree and improve the substitution uniformity. The morphology, specific surface area and crystalline structure of pristine cellulose, the as-synthesized alkali cellulose and dissolved-regenerated cellulose were characterized by SEM, BET, XRD and FT-IR, respectively. The results showed that the homogeneous reaction medium not only offered a low mass transfer resistance, but also facilitated a disruption of the hydrogen bond in cellulose, thus resulting in the transformation of the cellulose structure from complicated stacking chains to simple glucose chains. The interior hydroxyl groups in the cellulose became accessible to the alkaline reagent NaOH to enhance the alkalization process for the increase in bonding alkali content and the improvement in substitution uniformity. The bonding alkali content was calculated by the difference between total added alkali and free alkali and was achieved as 0.61 g/g cellulose at the optimized operation conditions: reaction temperature of 95 °C, reaction time of 90 min, NMMO dosage of 90.00 g, cellulose 1.0 g and NaOH concentration of 1.40 wt%. Meanwhile, in the conventional alkalization process, the bonding alkali content was just 0.41 g/g cellulose. The alkali cellulose prepared in NMMO/H₂O medium has a large specific surface area of 125 m² g^?1 and an extremely low crystallinity degree. The NMMO/H₂O system represents a potential homogeneous solvent for the cellulose alkalization process.     

Morphology of polysaccharide blend fibers shaped from NaOH, <Emphasis Type="Italic">N</Emphasis>-methylmorpholine-<Emphasis Type="Italic">N</Emphasis>-oxide and 1-ethyl-3-methylimidazolium acetate

The aim of this study was to find newly structured biopolymer blends bearing those adjustable features able to produce innovative materials. Apart from cellulose derivatives (cellulose carbamate and carboxymethyl cellulose), mannans (guar gum, locust bean gum, and tragacanth gum), xylan, starch (cationized), ι-carrageenan, and xanthan were chosen as blend polysaccharides for cellulose as matrix. In order to study their integration into the cellulose skeleton, fibers were shaped from three different solvents: NaOH by a special wet-spinning process, as well as N-methylmorpholine-N-oxide (NMMO) and 1-ethyl-3-methylimidazolium acetate (EMIMac) via Lyocell technology. The structure and morphologies of the fibers were analyzed by X-ray wide-angle scattering and atomic force microscopy. Hydrophilic/hydrophobic properties were determined by means of a contact angle, as well as moisture content and water retention values, while the surface properties throughout zeta-potential measurements. Being very different processes, the wet spinning in NaOH solution and the dry–wet spinning are deeply impacted by the types of solvent and polysaccharide. The X-ray results for NMMO fibers revealed the highest orientation compared with EMIMac having the lowest orientation of NaOH fibrous types. AFM images also show the lowest surface roughnesses for NMMO and EMIMac fibers. The moisture content and water retention values support these trends, while the water contact angle results show insignificant differences between the samples from EMIMac and NaOH, even though the values calculated for NMMO fibers were the lowest.     

Facile synthesis and biological evaluation of novel fluorine-containing <Emphasis Type="Italic">N</Emphasis>-nitro-<Emphasis Type="Italic">N</Emphasis>′-substituted phenylurea

Twenty-two novel N-nitro-N′-substituted phenyl-N-(2,6-dibromo-4-fluorophenyl)urea derivatives were designed and synthesized via a simple and convenient BTC ‘one-pot’ procedure using DMAP as the catalyst. The structures of all newly synthesized compounds were confirmed by IR, ¹H NMR, and elemental analysis, and a part has been identified by ¹³C NMR. The preliminary bioassay indicates that the target compounds possesses moderate herbicidal activity against Sorghum sudanense. However, some of the title compounds presented high plant growth regulating activity against rape.     

Competitive complexation in the copper(II) chloride-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylformamide-Aerosil system

Competitive complexation in the copper(II) chloride-N,N-dimethylformamide (DMF)-Aerosil system was studied by IR spectroscopy. It was found that adsorption from organic solutions containing copper(II) chloride and DMF resulted in the formation of the following three types of DMF complexes: self-associates of DMF, DMF complexes with surface hydroxyl groups, and DMF complexes with Cu(II) ions. The removal of DMF resulted in the sequential degradation of, initially, self-associates; next, complexes with silanol groups; and, finally, complexes with copper ions.Translated from Kinetika i Kataliz, Vol. 45, No. 6, 2004, pp. 917–920.Original Russian Text Copyright © 2004 by Golubeva, Zubareva.     

Oxidative Addition of <Emphasis Type="Italic">N</Emphasis>-Aminophthalimide to Conjugated and Nonconjugated Alkylazoalkanes

A series of γ,δ-unsaturated azo compounds was prepared by thermal isomerization of allylalkylhydrazones obtained from the simplest carbonyl compounds. The oxidation of N-aminophthalimide with lead tetraacetate in the presence of these unsaturated compounds gave rise to mixtures of adducts at the azo group, regioisomers of phthalimidoazimines. The oxidative addition of N-aminophthalimide to 1-isopropylazocycloalkenes afforded bicyclic C-isopropylazo-N-phthalimidoaziridines, but the same reaction with 2-alkylazopropenes did not result in any adducts with these conjugated azocompounds.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 2, 2005, pp. 214–223.Original Russian Text Copyright © 2005 by Kuznetsov, Belov, Buchaka.     

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.     

Ethylenebis(<Emphasis Type="Italic">N</Emphasis>-methylimidazolium) Chlorochromate (<Emphasis Type="Italic">EBMICC</Emphasis>): An Efficient and Selective Reagent for the Oxidation of Thiols to Disulfides

Summary. Ethylenebis(N-methylimidazolium) chlorochromate was prepared by addition of N-methylimidazole to 1,2-dibromoethane to form the corresponding dibromide salt and subsequent treatment of this salt with CrO₃ in 6N HCl solution. It is a stable yellow-orange solid, which oxidized thiols to the corresponding disulfides at room temperature. Selective oxidation of thiols in the presence of sulfides and hydroxyl groups was also achieved with this reagent.     

Thermodynamic characteristics of protolytic equilibria of ethylenediamine-<Emphasis Type="Italic">N,N</Emphasis>′-diacetic-<Emphasis Type="Italic">N,N</Emphasis>′-dipropionic acid

Heat effects of protonation and neutralization of ethylenediamine-N,N′-diacetic-N,N′-dipropionic acid at 298.15 K and ion force values of 0.1, 0.5, and 1.0 (KNO₃) were measured by the direct calorimetric method. Combined use of the results of thermochemical and potentiometric measurements carried out under the identical experimental conditions permitted to evaluate standard thermodynamic characteristics of the equilibria under study. The results obtained were compared with the corresponding data for related compounds considering the specific features of structure of the diamine complexones.     

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.     

Synthesis of <Emphasis Type="Italic">N</Emphasis>-Arylsulfonyl-α-thienylglycines from <Emphasis Type="Italic">N</Emphasis>-(2,2,2-Trichloro-1-thienylethyl)arenesulfonamides

Reactions of N-(2,2,2-trichloroethylidene)arenesulfonamides with thiophene, 2-chlorothiophene, and 2,5-dichlorothiophene, as well as of N-(2,2,2-trichloro-1-hydroxyethyl)arenesulfonamides with 2-chlorothiophene, lead to formation of the corresponding N-(2,2,2-trichloro-1-thienylethyl)arenesulfonamides. Alkaline hydrolysis of the latter occurs selectively at the trichloromethyl group to give N-arylsulfonyl-α-thienylglycines.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 1, 2005, pp. 93–96.Original Russian Text Copyright © 2005 by Aizina, Rozentsveig, Ushakova, Levkovskaya, Mirskova.     

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.     

Contribution to the Protonation of a Calix[4]arene: DFT Calculated Structure of Protonated <Emphasis Type="Italic">p-tert</Emphasis>-Butylcalix[4]arenetetrakis(<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-diethylacetamide)

Summary. By using DFT calculations, the most probable structure of the p-tert-butylcalix[4]arenetetrakis(N,N-diethylacetamide) · H₃O⁺ complex species was derived. In this complex, the hydroxonium ion H₃O⁺ is predominantly bound by strong hydrogen bonds to three phenoxy oxygens of the ligand and partly to the remaining phenoxy oxygen atom by two somewhat weaker hydrogen bonds. Besides, the H₃O⁺ cation is also bound to two carbonyl oxygens of the mentioned ligand by further two weaker hydrogen bonds.     

Structure and photochromism of 2-(<Emphasis Type="Italic">N</Emphasis>-acyl-<Emphasis Type="Italic">N</Emphasis>-arylaminomethylene)benzo[<Emphasis Type="Italic">b</Emphasis>]thiophen-3(2<Emphasis Type="Italic">H</Emphasis>)-ones

It was shown by electron absorption spectroscopy and X-ray diffraction analysis that steric strains in photochromic 2-(N-acyl-N-arylaminomethylene) benzo[b]thiophen-3(2H)-one molecules ortho-substituted in the N-phenyl ring increase the quantum yield of the N→O photoinduced rearrangement in accord with an increase in the steric constant of the ortho-substituent.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2151–2155, October, 2004.     

Electrochemical polymerization of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′-bis(3-methoxysalicylidene)-1,3-propylenediamine

The electrochemical oxidation of N,N′-bis(3-methoxysalicylidene)-1,3-propylenediamine leads to the formation of conducting polymer on the electrode surface. The decisive role of phenol oxygen in the formation of the polymeric forms of azomethine bases was elucidated. Optimal conditions for the synthesis of the polymer in the potentiostatic conditions were revealed. The coefficient of the charge diffusion and the activation barrier for the charge transfer in the polymer bulk in the electrolyte medium were determined.     

Structure and intermolecular interactions of <Emphasis Type="Italic">N</Emphasis>-(3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-4-hydroxybenzyl)thioureas

The molecular and crystal structure and the hydrogen bonding in crystal and in solutions of N-phenyl-N-(3,5-di-tert-butyl-4-hydroxybenzyl)thiourea and N-(3,5-di-tert-butyl-4- hydroxybenzyl)thiourea were studied by single crystal X-ray diffraction and IR spectroscopy. The intermolecular interactions of these compounds are essentially different.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1864–1870.Original Russian Text Copyright © 2004 by Bukharov, Litvinov, Gubaidullin, Chernova, Shagidullin, Nugumanova, Mukmeneva.This revised version was published online in April 2005 with a corrected cover date.     

Reactions of <Emphasis Type="Italic">N</Emphasis>-and <Emphasis Type="Italic">C</Emphasis>-Alkenylanilines: VII. Synthesis of Indole Heterocycles from Products of Reaction between <Emphasis Type="Italic">N</Emphasis>-Mesyl-2-(1-alken-1-yl)anilines and Halogens

N-Mesyl-2-(1-methyl-1-butenyl)-6-methylaniline reacted with Br₂ to afford N-mesyl-2-(3-bromo-1-penten-2-yl)aniline that under treatment with NH₃ or amines underwent cyclization into N-mesyl-7-methyl-3-methylene-2-ethylindoline. The reaction of N-mesyl-2-(1-methyl-1-buten-1-yl)-4-methyl- and 2-(1-methyl-1-buten-1-yl)aniline with Br₂ gave rise to the corresponding N-mesyl-2-(2-bromo-1-methyl-1-buten-1-yl)anilines. Under the similar conditions N-tosyl-2-(1-cyclohexen-1-yl)aniline was converted into N-tosyl-2-(6-bromo-1-cyclohexen-1-yl)aniline that under treatment with NH₃ furnished N-tosyl-1,2,3,9a-tetrahydrocarbazole. The reaction of N-mesyl-1,2,3,9a-tetrahydrocarbazole with CuBr₂ in MeOH afforded N-mesyl-4-methoxy-1,2,3,4-tetrahydrocarbazole. N-Mesyl-6-methyl-2-(1-cyclopenten-1-yl)aniline in reaction with Br₂ in the presence of NaHCO₃ was oxidized into the corresponding cyclopentenone, and with NBS it gave N-mesyl-2-(2-bromo-1-cyclopenten-1-yl)aniline.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 730–737.Original Russian Text Copyright © 2005 by Gataullin, Sotnikov, Spirikhin, Abdrakhmanov.     

Syntheses proceeding from <Emphasis Type="Italic">N</Emphasis>-(oxiran-2-ylmethyl)-<Emphasis Type="Italic">N</Emphasis>-ethylaniline

The preparation of N-(oxiran-2-ylmethyl)-N-ethylaniline was developed. The compound was used in the synthesis of new N-derivatives of aromatic amines containing vicinal aminoalcohol moieties.