Photolysis of <Emphasis Type="Italic">meta</Emphasis>-azidophenol in solutions

The photolysis of meta-azidophenol in various organic solvents and aqueous solutions is studied by IR spectroscopy, electronic absorption spectroscopy, thin-layer chromatography (TLC), and analytical spot-test reactions. The polymeric derivatives of hydroxylamine are formed in organic solvents (benzene, chloroform, acetonitrile) via the interaction of nitrene with the phenol group of a neighboring m-azidophenol molecule. N-(meta-Hydroxyphenyl)hydroxylamine,—the product of the nitrene reaction with water, is formed in ethanol and aqueous solutions.     

Solvent dependent swelling behaviour of poly(<Emphasis Type="Italic">N</Emphasis>-vinylcaprolactam) and poly(<Emphasis Type="Italic">N</Emphasis>-vinylcaprolactam-<Emphasis Type="Italic">co</Emphasis>-itaconic acid) gels and determination of solubility parameters

Swelling behaviour of poly(N-vinylcaprolactam) (PVC) and poly(N-vinylcaprolactam-co-itaconic acid) (P(VC-co-IA)) gels was investigated in different solvents (water, ethanol, methanol, isopropyl alcohol (IPA), chloroform, toluene, acetone) and in binary solvent mixtures (ethanol/chloroform, ethanol/methanol, IPA/chloroform, ethanol/water, IPA/water). Gels were synthesised in ethanol by the free radical cross-linking polymerisation method at 60°C for 24 h in the presence of azo-bis(isobutyronitrile) and allyl methacrylate as the initiator and cross-linker, respectively. And also, ethanol/distilled water mixture (?_r = 4:1) was used as the synthesis medium to determine its effect on the swelling of gels. It was found that the presence of water in the synthesis medium significantly affected the equilibrium swelling value (ESV) and the swelling tendency of gels both in solvents and in solvent mixtures. All gels synthesised in ethanol showed the highest swelling in chloroform. The gels synthesised in the ethanol/water mixture displayed different swelling behaviour. In this case, while chloroform was still valid for maximum swelling of PVC, P(VC-co-IA) had the highest swelling in methanol. Solubility parameters of gels were predicted by the van Krevelen-Hoftyzer (VKH) and Hoy methods (group contribution methods) and theoretical calculations verified the experimental swelling order.     

Oligomerization of <Emphasis Type="Italic">N</Emphasis>-vinylpyrroles under the action of iodine

The oligomerization of N-vinylpyrroles (N-vinyl-4,5,6,7-tetrahydroindole, N-vinyl-2-[1-(1-4,5,6,7-tetrahydroindole)ethyl]-4,5,6,7-tetrahydroindole, N-vinyl-2-phenylpyrrole, N-vinyl-3-heptyl-2-phenylpyrrole, N-vinyl-2,3-diphenylpyrrole, and N-vinyl-2-(2-naphthyl)pyrrole) under the action of iodine vapor leads to the formation of iodine-containing oligomers with an iodine content of 17–52% and a yield of up to 99%. The oligomers are paramagnetic and possess conductivity; they are readily soluble in organic solvents (benzene, dioxane, and chloroform) and are stable up to 110–260°C.     

Free-Radical Co-Oligomerization of <Emphasis Type="Italic">N</Emphasis>-Vinylpyrroles with <Emphasis Type="Italic">N</Emphasis>-Vinylpyrrolidone: A Route to New Bioactive Oligomers

Co-oligomerization of N-vinylpyrroles (N-vinyl-2,3-dimethylpyrrole, N-vinyl-2-phenylpyrrole, N-vinyl-2,3-diphenylpyrrole, N-vinyl-2-(2-thienyl)pyrrole, and N-vinyl-2-[1-(4,5,6,7-tetrahydroindolyl) ethyl]-4,5,6,7-tetrahydroidole) with N-vinylpyrrolidone in the presence of a radical initiator (AIBN) gives co-oligomers with molecular masses of 1600–5200 in up to 87% yield. The products are readily soluble in organic solvents (benzene, 1,4_dioxane, and chloroform), and in the case of high N-vinylpyrrolidone content, also in ethanol and in water. The co-oligomers are non-toxic or have low toxicity (the lethal dose LD₅₀ = 1300–2000) and possess biological activity.     

Thermooxidative decomposition of heterocyclic <Emphasis Type="Italic">N</Emphasis>-oxides

Thermooxidative decomposition of pyridine N-oxide, 4-(4-dimethylaminostyryl)pyridine N-oxide, 4-(4-methoxystyryl)pyridine N-oxide, quinoline N-oxide, 2-methylquinoline N-oxide, 4-chloroquinoline N-oxide, 2-styrylquinoline N-oxide, and 2-(4-dimethylaminostyryl)quinoline N-oxide was studied. The kinetic parameters of the thermooxidative processes were calculated according to three independent procedures. The relation between the nature of heterocyclic N-oxide and its stability to thermal oxidation was analyzed.     

Alkylation of 2-(methylsulfanyl)-6-polyfluoroalkylpyrimidin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones with haloalkanes

The alkylation of ambident anions of 2-(methylsulfanyl)-6-(polyfluoroalkyl)pyrimidin-4(3H)-ones with 4-bromobutyl acetate leads to concurrent formation of O- and N-(4-acetoxybutyl) derivatives. Polar aprotic solvents favor formation of the O-isomer, and weakly polar dioxane favors N-alkylation. The reaction of 2-(methylsulfanyl)-6-(trifluoromethyl)pyrimidin-4(3H)-one with an equimolar amount of 1,2-dibromoethane in polar acetonitrile gives a mixture of N,N-, O,O-, and N,O-bridged bis-pyrimidines, as well as N- and O-[2-(methylsulfanyl)ethyl] derivatives, whereas in the presence of 10 equiv of 1,2-dibromoethane the N,O-isomer is formed as the only product. The reaction in weakly polar tetrahydrofuran yields N,N- and N,O-bispyrimidines.     

Photolysis of <Emphasis Type="Italic">ortho</Emphasis>-azidophenol in various solvents

The photolysis of ortho-azidophenol in water, ethanol, acetonitrile, chloroform, and benzene was studied by IR and electronic spectroscopy and thin-layer chromatography. It was found that an equilibrium between ortho-azidophenol and its quinonoid form occurred in benzene. In the photolysis of ortho-azidophenol in benzene, intramolecular hydrogen bonding facilitates the degradation of the azido group through the mechanism of formation of intermediate triazene structures. In the other solvents, which exclude intramolecular hydrogen bonding, the nitrene mechanism of photolysis yielding ortho-aminophenol, ortho-iminoquinone, and an azo compound is operative. The rate of formation of photolysis products depends on the nature of the solvent.     

Phase-equilibrium and cellulose-coagulation kinetics for cellulose solutions in <Emphasis Type="Italic">N</Emphasis>-methylmorpholine-<Emphasis Type="Italic">N</Emphasis>-oxide

The dissolution of cellulose in N-methylmorpholine-N-oxide monohydrate and the dissolution of N-methylmorpholine-N-oxide monohydrate in water have been studied via optical interferometry. A part of the phase diagram for the cellulose/N-methylmorpholine-N-oxide system has been constructed. The phase diagram is characterized by crystalline equilibrium, hysteresis of the melting temperatures of the solvents, and a region of anisotropy. Optical interferometry has been used for the first time to study the kinetics of cellulose coagulation during the interaction of cellulose solutions in N-methylmorpholine-N-oxide with water and water solutions of N-methylmorpholine-N-oxide. Information on the values of interdiffusion coefficients and the morphologies of the resulting cellulose films has been obtained. The possibility to use optical interferometry to analyze the interaction of a solution with the coagulating agent in the case of cellulose fiber and film formation has been demonstrated. The influences of temperature, the nature of the coagulating agent, and the cellulose content on the kinetics of the process and morphologies of the formed films have been shown. The use of N-methylmorpholine-N-oxide as a part of the coagulation system decreases the rate of interdiffusion of solutions, thereby resulting in a more uniform and dense morphology of cellulose films. Increased temperature causes diffusion acceleration, thereby leading to the formation of an anisotropic morphology of the cellulose films.     

Stereochemistry of dihydroxylation of <Emphasis Type="Italic">N</Emphasis>-arylbicyclo[2.2.1]-hept-5-ene-<Emphasis Type="Italic">endo</Emphasis>- and -<Emphasis Type="Italic">exo</Emphasis>-2,3-dicarboximides

Stereochemistry of the oxidation of N-arylbicyclo[2.2.1]hept-5-ene-endo-and-exo-2,3-dicarboximides at the double bond with peroxyacetic acid generated in situ in the presence of sulfuric acid and with an anhydrous dioxane solution of peroxyacetic acid was studied. In both cases, the reaction was stereospecific, regardless of the substituent in the N-aryl group and configuration of the imide ring, but the reaction direction depended on the presence of water in the system. In the first case, the corresponding trans-5,6-dihydroxy derivatives were formed, while in the second, exo-5,6-epoxy derivatives. The oxidation of N-arylbicyclo[2.2.1]-hept-5-ene-endo-and-exo-2,3-dicarboximides with a solution of potassium permanganate in aqueous acetone gave the corresponding N-aryl-cis-5,6-dihydroxybicyclo[2.2.1]heptane-endo-and-exo-2,3-dicarboximides. The exo,cis,exo and exo,cis,endo configurations of the synthesized compounds were determined by ¹H NMR spectroscopy.     

Radical copolymerization of <Emphasis Type="Italic">N,N</Emphasis>-diallyl-<Emphasis Type="Italic">N,N</Emphasis>-dimethylammonium chloride and maleic acid in various solvents

Radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride with maleic acid in various solvents was studied. The solvent effect on the relative activity of the monomers and the possibility of preparing copolymers of preset composition were examined.     

Influence of mixed common solvent on the co-assembled morphology of PS-<Emphasis Type="Italic">b</Emphasis>-PEO and CdS quantum dots

The hybrid structures of polystyrene-b-poly(ethylene oxide) (PS-b-PEO) block copolymer and inorganic nanoparticles with good stability and biocompatibility have potential applications in drug delivery and bioimaging. Spherical co-assemblies of PS₁₂₀-b-PEO₃₁₈ and oleylamine-capped CdS quantum dots (QDs) are produced successfully in this work by adding water to a mixed common solvent, such as N,N-dimethylmethanamide (DMF)/chloroform, DMF/tetrahydrofuran (THF), or DMF/toluene. The energy dispersive X-ray (EDX) spectrum indicates that QDs are located at the interface between the core and shell of the spherical co-assemblies. The co-assembly process during water addition is traced by transmission electron microscopy (TEM) and turbidity measurement. Spherical co-assemblies are formed through budding from bilayers of the block copolymer and QDs. The morphology of the co-assemblies is related to the miscibility of the QD-dispersing solvents with water and the morphology changes from a spherical to a vesicle-like structure with DMF/toluene. Increasing THF content in the mixed solvent causes morphological transitions from spherical co-assemblies to multi-branched cylinders and micelles where QDs are located in the central core. Increasing chloroform content yields vesicle-like structures with protruding rods on the surface. The mechanism of the morphological transitions is also discussed in detail.     

Influence of the Molecular Mass of Poly(<Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone) on Formation of Cu<Subscript>2</Subscript>O Nanoparticles During Reduction of Divalent Copper Ions with <Emphasis Type="Italic">tert</Emphasis>-Butylamine Borane in Polymer Solution

The process of reduction of divalent copper ions with tert-butylamine borane in dilute aqueous solutions of poly(N-vinylpyrrolidone) is investigated. The influence of polymer molecular mass on properties of the resultant Cu₂O sols is studied. It is shown that Cu₂O nanoparticles with an average diameter of 6–8 nm independent of polymer molecular mass and a relatively narrow size distribution of particles are formed in the systems under study. The contour length of macromolecules and the hydrodynamic diameter of a poly(N-vinylpyrrolidone) macromolecular coil are compared with the diameter of Cu₂O particles. Poly(N-vinylpyrrolidone) with M ≥ 1 × 10⁴ can be used to produce Cu₂O nanoparticles. Poly(N-vinylpyrrolidone) with M > 4 × 10⁴ should be used for the formation of long-living Cu₂O sols.     

Electrophilic cyclization of <Emphasis Type="Italic">N</Emphasis>-allyl(propargyl)-5-amino-1<Emphasis Type="Italic">H</Emphasis>-pyrazole-4-carboxamides. Synthesis of 4-[(dihydro)oxazol-2-yl]-1<Emphasis Type="Italic">H</Emphasis>-pyrazol-5-amines

N-Allyl-5-amino-1H-pyrazole-4-carboxamides in reactions with polyphosphoric acid, with N-halosuccinimides in chloroform, and with (chlorosulfanyl)benzenes in nitromethane in the presence of lithium perchlorate underwent cyclization involving the N-allylamide fragment to give 4-[5-methyl(halomethyl)-4,5-dihydrooxazol-2-yl]-1H-pyrazol-5-amines and 2-(5-amino-1H-pyrazol-4-yl)-5-[(arylsulfanyl)methyl]-4,5-dihydro-1,3-oxazolium perchlorates, respectively. Analogous reactions of N-propargyl-5-amino-1H-pyrazole-4-carboxamides with polyphosphoric acid afforded 4-(5-methyloxazol-2-yl)-1H-pyrazol-5-amines, and with (chlorosulfanyl) benzenes, 2-(5-amino-1H-pyrazol-4-yl)-5-[(arylsulfanyl)methylidene]-4,5-dihydro-1,3-oxazolium perchlorates.     

Solubility of <Emphasis Type="Italic">d</Emphasis>-elements salts in organic and aqueous-organic solvents: IV. Solubility of cadmium chloride

Solubility of cadmium chloride at 25°C in four ternary systems containing mixed water-organic solvents was measured by the isothermal saturation method. Dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, and 1,4-dioxane were used as organic components. In all systems the organic component addition provides a salting-out effect within the whole range of the binary solvent compositions.     

Thermoresponsive behavior of water-salt solutions of a graft copolymer with a main polyimide chain and side poly(<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylamino-2-ethyl methacrylate) side chains

The water-salt solutions of the graft copolymer bearing a polyimide main chain and poly(N,N-dimethylamino-2-ethyl methacrylate) side chains (M = 4.7 × 10⁵, the density of grafting with side chains z = 0.44) are studied by static and dynamic light scattering and turbidimetry. The solutions are investigated in a tenfold range of NaCl concentrations (from 0.015 to 0.15 mol/L) at the polymer concentration from 0.002 to 0.015 g/cm³ and pH from 8 to 12. The temperature dependences of the intensity of scattered light, optical transmission, hydrodynamic radius of scattering objects, and their concentrations in solutions are derived. The temperatures of phase separation onset T ₁ and end T ₂ are determined. It is shown that an increase in the salt content in solution leads to reduction in the polymer solubility and in temperatures T ₁ and T ₂. The watersalt solutions retain all the regularities of phase-separation temperature variation observed for aqueous solutions with change in the concentration of solution and pH of a medium: the values of T ₁ and T ₂ increase upon dilution and growth of acidity.     

3-(1-Methyl-1-nitroethyl-1-<Emphasis Type="Italic">ONN</Emphasis>-azoxy)-4-aminofuroxan. Synthesis and transformations of the amino group

A four-step procedure to convert 4-(1-methyl-1-nitroethyl-1-ONN-azoxy)-3-cyanofuroxan into 3-(1-methyl-1-nitroethyl-1-ONN-azoxy)-4-aminofuroxan was developed. The pathways of transformation of the amino group of the synthesized compound into N-nitramino-, N-alkyl-N-nitramino-, N,N’-methylenediamino-, N,N’-methylene-N,N’-dinitramino-, and azo groups were studied.     

Effect of molecular weight of poly-<Emphasis Type="Italic">N</Emphasis>-benzyl-<Emphasis Type="Italic">N,N</Emphasis>-dimethyl-<Emphasis Type="Italic">N</Emphasis>-methacryloyloxyethylammonium chloride on its complexation with sodium dodecyl sulfate

Complexation of a cationic polyelectrolyte, poly-N-benzyl-N,N-dimethyl-N-methacryloyloxyethylammonium chloride, with an ananionic surfactant, sodium dodecyl sulfate, in aqueous solutions is studied. The effect of the molecular weight of the polymer on phase separation in the system and on the stability, conformation, and surface activity of the polyelectrolyte-surfactant complexes is examined.     

Liquid Extraction of Noble Metal Ions with an α-Amino Phosphonate

The extraction of Au(III), Pt(IV), and Pd(II) ions from aqueous hydrochloric acid solutions with solutions of bis(2-ethylhexyl) N-butyl-N-octylaminomethylphosphonate in chloroform and xylene was studied. The recovery of the noble metal ions is the most efficient at low acidities of the aqueous solution, with a high selectivity of separation from the concomitant Fe(III), Cu(II), Ni(II), and Co(II) ions.     

Reaction of <Emphasis Type="Italic">N</Emphasis>-chloroamines with carbanions derived from ethyl acetoacetate and diethyl malonate

Carbanions derived from ethyl 3-oxobutanoate and diethyl malonate reacted with an equimolar amount of N-chloro-N-ethylethanamine, N-chloromorpholine, or N-chloropiperidine to give diethyl 2,3-diacetylbutanedioate and tetraethyl ethane-1,1,2,2-tetracarboxylate in 68–83% yield. The possibility of heterocoupling of ethyl 3-oxobutanoate and diethyl malonate carbanions by the action of N-chloro-N-ethylethanamine and the effect of the molar reactant ratio on the selectivity of oxidative homo- and heterocoupling were studied.     

Solutions of mixtures of cellulose and synthetic polymers in <Emphasis Type="Italic">N</Emphasis>-methylmorpholine-<Emphasis Type="Italic">N</Emphasis>-oxide

Phase state and morphological features of solutions of cellulose blends with rigid-chain thermotropic LC copolyesters and isotropic poly(m-phenyleneisophthalamide) in the highly polar donor solvent N-methylmorpholine-N-oxide are studied by DSC and polarization microscopy. The ternary phase diagram for the cellulose-copolyesters-N-methylmorpholine-N-oxide system is constructed. Rheological characteristics of the prepared solutions are studied using capillary and rotary rheometers under the regimes of continuous and periodic shear deformation. Rheological characteristics of cellulose solutions with copolyesters in N-methylmorpholine-N-oxide with their different phase states are shown to change in accordance with the traditional mechanism of flow for solutions with high specific interactions between their components. However, the character of the rheological behavior of mixtures of cellulose with poly(m-phenyleneisophthalamide) in N-methylmorpholine-N-oxide primarily stems from structural-morphological transformations in solutions taking place upon deformation.