Aprotonic Solvents Research Articles

SYNTHESIS OF SUPER-BRANCHED POLYGLYCERIDES OF SACCHARIN-6-CARBOXYLIC ACID

By polycondensation of triglyceride of saccharin-6-carboxylic acid with some aliphatic diamines, the thermal-stable super-branched polyestersulfoimides – polyglycerides of saccharin-6-carboxylic acid have been obtained. The structures of the synthesized compounds have been confirmed by data of the IR spectroscopy. The yield of the purposeful product was 80–83%. It has been found that the synthesized polyglycerides are well dissolved in polar aprotonic solvents. The thermal stability of the obtained compounds was studied by a method of differential-thermal analysis on derivatograph of system ʺPaulik-Paulik-Erdeyʺ. The derivatographic investigations showed that the synthesized polyglycerides have high thermal stability, decreasing with the growth of length of the aliphatic fragment in their composition. For comparative estimation of the thermal and physical-mechanical indices of the synthesized polyglycerides, the corresponding indices of the industrial polyesterimide Zellamid 1000 have been also given. It has been found that the obtained polyglycerides do not concede to industrial polyesterimides on physical-mechanical indices, but exceed them on thermal stability

Crosslinked Sodium Alginate as a Material for Nanolfiltration Protonic and Aprotonic Solvents

In this work, for the first time, salts of bivalent and trivalent metals were used as crosslinking agents for nanofiltration membranes based on sodium alginate. The developed membranes were investigated for chemical stability in protic and aprotic solvents, the dependence of the permeability of these solvents on their sorption into the membrane material was obtained. The separating properties of membranes based on sodium alginate crosslinked with metal cations were investigated. The retention coefficient of the model substance with a molecular weight of 626 g/mol, dissolved in ethanol, was 97%.

Conductivity of Nafion-117 membranes intercalated by polar aprotonic solvents

The Nafion-117 membranes in the Li+ form with pore-intercalated aprotonic organic solvents were prepared. The prepared materials were characterized by IR, impedance, and 7Li NMR spectroscopy. The solvent uptake of the membranes is shown to be controlled by the composition of organic solvents and their mixtures as well as by the conditions of the preliminary treatment of the initial membranes. For the Nafion-117 membrane, the degree of solvation can be improved by the preliminary treatment with alcohols, especially by the thermal treatment in methanol. Conductivity of the membranes is shown to increase with increasing content of the sorbed solvents. The best conductivity at 25 °C (2.5 × 10−3 and 1.6 × 10−3 S cm−1) was attained for the electrolytes based on the Nafion-117 membrane in lithium form with sorbed ethylene carbonate-propylene carbonate and ethylene carbonate-dimethoxyethane mixtures, respectively.

Formation of the second superhydrophobic shell around an encapsulated metal ion: synthesis, X-ray structure and electrochemical study of the clathrochelate and bis-clathrochelate iron(ii) and cobalt(ii,iii) dioximates with ribbed perfluoroarylsulfide substituents

The nucleophilic substitution of six chlorine atoms of the n-butylboron-capped clathrochelate iron and cobalt(II) precursors with perfluoroarylthiolate anions afforded the hexaperfluoroarylsulfide macrobicyclic iron and cobalt(II) tris-dioximates. The complexes obtained are soluble in aromatic and aliphatic hydrocarbons as well as in polar aprotonic solvents due to the presence of the superhydrophobic fluorine-containing molecular periphery. As it follows from the X-ray data for five iron and cobalt mono- and bis-clathrochelates, the geometry of their macrobicyclic frameworks is affected by both the nature of an encapsulated metal ion and that of the ribbed substituents. Bis-capping fragment Co(II)O(6) of the Co(III)Co(II)Co(III) bis-clathrochelate possesses a trigonal antiprismatic geometry, all the Co(II)N(6) coordination polyhedra are trigonal-prismatic, and those of the encapsulated iron(II) and cobalt(III) ions are intermediate between them. The wide range of Co-N distances as well as the significant shifts of the encapsulated cobalt(II) ions from the centres of their N(6)-coordination polyhedra were explained by the Jahn-Teller distortion. The EPR and magnetometry data are also characteristic of the low-spin cobalt(II) complexes with this distortion. The parameters of the (57)Fe Mössbauer spectra of the iron macrobicycles are characteristic of the low-spin iron(II) complexes. The cyclic voltammograms (CVs) for the complexes studied contain the one-electron oxidation and reduction waves assigned to metal-centered redox-processes. The Fe(2+/3+) and Co(2+/3+) oxidations are quasi-reversible or irreversible. The anionic clathrochelate species resulting from the reversible Co(2+/+) reductions are stable on the CV time scale, whereas their iron(I)-containing analogs are unstable.

ИзучЕниЕ кИнетИкИ реакциЙ арилатоВ натриЯ С эпихлоргидриноМ

The kinetic reactions of arylates (4-metoxiphenolate, 2,4-dibromphenolate, pentabromphenolate) natrium with epicholorohydrin in the protonic and aprotonic solvents have been studied. It was shown, that the reaction it is necessary conduct in the isopropanol

Synthesis of fluorinated polystyrene

Acylation of polystyrene with trifluoroacetic anhydride in a solution of aprotonic solvents, namely 1,2-dichloroethane, chlorobenzene at the presence of Lewis acid as catalyst results in obtaining of fluorinated polystyrene, which posses trifluoroacetic fragments in benzoic rings, preferably in position 4. In order to achieve a total substitution of benzene rings in polystyrene macromolecules, the ratio polystyrene : trifluoroacetic anhydride : AlCl3 must be at least 1:10:2.2 mol correspondingly

Catalytic oxidation of anisole over titanium silicalite‐1

AbstractThe reaction of anisole hydroxylation with hydrogen peroxide to form methoxyphenols over TS‐1 was studied. Four C1‐C3 alcohols and the two aprotonic solvents acetone and acetonitrile were used. Product conversion was almost proportional to the titanium content of the catalyst sample. The highest conversion and p‐selectivity were observed in ethanol. Some speculations, based on the formation of substrate‐solvent or titanium‐solvent‐oxidant complexes, about the role of the solvent are presented. It was found that in all the solvents studied the p/o ratio increased with time.

New Nucleophilic Arylating Reagents: Tris(pentafluorophenyl)phosphine, -arsine and -stibine

Tris(pentafluorophenyl)-substituted pnictogenes (excluding nitrogen) are able to arylate electrophilic compounds containing active halogen atoms in the presence of CsF in bipolar aprotonic solvents.

Electronic structure, complexing, and copolymerization of itaconic acid in solution

The electronic structure parameters of free itaconic acid and itaconic acid found in complexes are calculated, and the higher acidity of the α-carboxyl group is highlighted. The complexing of itaconic acid in aprotonic solvents of high electron donor capacity and in water is studied, and the activity of the monomer in complexes is evaluated. The copolymerization of itaconic acid with acrylonitrile, methacrylonitrile, and chloroethyl methacrylate in DMSO-water solutions is studied. The special features and differences in the copolymerization of itaconic acid and monocarboxylic acids in a mixed solvent are discussed.

On the role of complexation with a solvent in the formation of supermolecular structures of polyamic acids

A study has been made of features of complexation of polyamic acids with aprotonic solvents. It is shown that a polyamic acid film is a solid solvocomplex with an aprotonic solvent that contains two solvent molecules per repeat-unit of the polymer. By changing the chemical nature of the solvent included in the solvocomplex one can control the formation of supermolecular structure in nonoriented polyamic acid films.

Pyryliumverbindungen. 30. C‐Alkylierung von 1,3,5‐Triaryl‐penten‐1,5‐dion‐Enolaten: Ein einfacher Zugang zu 3‐alkylsubstituierten 2,4,6‐Triaryl‐pyryliumsalzen

Pyrylium Compounds. 30. C‐Alkylation of 1,3,5‐Triaryl‐pentene‐1,5‐dione Enolates: A Simple Approach to 3‐Alkylsubstituted 2,4,6‐Triarylpyrylium Salts1,3,5‐Triaryl‐pentene‐1,5‐dione enolates (10), obtainable in crystalline form from 2,4,6‐triarylpyrylium pseudobases (9) and sodium methoxide in benzene/ether, react in dipolar aprotonic solvents (e.g. DMSO, DMF) with various types of alkyl iodides to give C‐alkylation products (11) which afford 3‐substituted 2,4,6‐triarylpyrylium salts (12) on treatment with perchloric acid. This reaction sequence proved to be a convenient synthetic route to pyrylium salts (12) having 3‐oriented substituents such as normal or branched alkyl groups CnH2n+1 (e.g.n = 1–5), isotopically modified alkyl groups (e.g. C[2H3], C2[2H5]), allyl type substituents (e.g. CH2CHCH2, MeCHCHCH2, CH2, CH2CMeCH2) or benzyl groups (e. g. PhCH2, 4‐BrC6H4CH2). Bifunctional alkylating agents (e.g. 1,4‐diiodobutane, o‐xylylenediiodide) resulted in a novel type of bispyrylium salts (14) with 3,3′‐linkage. The pyrylium salts obtained were characterized by their 1H‐n.m.r. and u.v. spectra as well as, in most cases, by transformation into the corresponding pyridine derivatives (13) and bispyridines (15) respectively.

Molecular interactions in polymeric amido-salt solutions

Nuclear magnetic resonance, IR spectroscopy and solution calorimetry have been used to investigate solutions of poly- m-phenylene isophthalamide in aprotonic solvents in the presence of various salts. It has been shown that salts capable of existing in the form of ion pairs exert an influence on the solubility of the polymer. The interaction that thus occurs between the dipole of the ion pair and the polymer's amide group leads to polarization of the macromolecule and causes interaction between the planar groups of the polymer chain and associates of solvent molecules.

Reaction of water with aprotonic solvents

Reaction of water with aprotonic solvents

Study of acidic-basic properties of polymeric hydroxyazophenyl acetylene dyes with the help of electronic absorption spectra

Poly- p-aminophenylacetylene was used to synthesize seven hydroxyazo-compounds and with the help of absorption spectra in the visible range their acidic-basic properties were examined. It was shown that hydroxyazo-compounds of benzene series in neutral solutions exist in the azo-form, while compounds of the naphthalene series—mainly in the quinone-hydrazone form. A mesomeric anion is formed in alkaline solutions, the structure of which is close to quinone-hydrazone, particularly in aprotonic solvents of DMSO and DMF.

Reaction of water with aprotonic solvents

We have investigated the character of the interaction of water in amide-salt systems and have developed a spectral method of determining low water contents in N-methylpyrrolidone (NMP) and dimethylacetamide (DMAc), both pure and containing lithium chloride. To free the solvents from water, they were purified by distillation and then were dried over molecular sieves for five days. To avoid incidence of atmospheric moisture into the solvents, preparation of solutions and filling of cuvettes with them was carried out in a dry box. Spectra were recorded on double-beam UR-20 or IR-75 spectrophotometers. We investigated water content in organic solvents having the following concentrations of it: in DMAc, 0.01-1% in the absence of LiCI, and with LiCI concentrations of 2.5, 3.5, and 5.0%; for more accurate determination of microquantities of water in DMAc, 0.01-1%, with no LiCI and with an LiCI concentrationof 2.5, 3.5, and 5.0%; in NMP, of 0.03-0.3%. We used sectional standard cuvettesof thiekness0.O04, 0.007, 0.024, and 0.026 cm, with windows of KBr and NaCI, selecting the thickness of the absorbing layer from the optimum in absorption of the analytical band.

Thermophysical characteristics of aprotonic solvents and electrolytes based on them

Measured and computed values of the thermal conductivity and heat capacity of a number of organic solvents and electrolytes based on them are presented.

Heterogeneous equilibrium between the condensed phase and vapor of aprotonic solvents and electrolytes based on them II. Solvent mixtures

Experimental results for the saturated vapor pressure of mixtures of organic solvents with electrolytes based on them are given, together with thermodynamic characteristics of the vaporization process calculated on this basis.

Heterogeneous equilibrium of condensed gas-vapor aprotonic solvents and electrolytes based on them. I. Individual solvents

The results of an experimental determination of the saturated-vapor pressure of organic solvents and electrolytes based on them are presented, and used to calculate the thermodynamic characteristics of the vaporization process.

Viscosity and density of aprotonic solvents and electrolytes based on them

The results of an experimental determination of the viscosity and density of organic solvents and electrolytes based on them are given.

Luminescence and laser radiation of complexes with hydrogen bond of 4-methyl-7-oxycoumarine in aprotonic solvents

Luminescence and laser radiation of complexes with hydrogen bond of 4-methyl-7-oxycoumarine in aprotonic solvents