Polyaryleneimides of meso- and dl- 1,2,3,4-butanetetracarboxylic acid dianhydrides

High molecular weight polyarylene amic acids have been prepared by reacting aromatic diamines with equimolar amounts of either meso-or dl-1,2,3,4-butanetetracarboxylic acid dianhydride (TCBA) in organic polar solvents. Heat converted these soluble precursors to insoluble polyimides having good high-temperature physical properties.     

Kinetics of heterogeneous cellulose reactions. I. Cyanoethylation of cotton cellulose

Sakurada's equation and fundamental kinetic laws were applied to the heterogeneous cyanoethylation of cellulose, performed by reacting fiber with liquid acrylonitrile, with sodium hydroxide as the catalyst. The data fit Sakurada's equation better at higher temperatures; deviation occurs at the initial stage, and the rate of reaction falls abruptly at a later stage. The degree of substitution at which the abrupt rate change occurred decreased as the temperature increased from 31 to 60°C. and also as the crystallinity of the fiber decreased. Diluting the reagent with different solvents decreased the rate of reaction and changed its transition points, but did not change the essential nature of the reaction, each segment of which fits Sakurada's equation very well. A uniform distribution of the catalyst (sodium hydroxide) throughout the fiber was attempted, and then the reaction was studied at 50°C. Diffractograms of the samples provided further evidence that the position of the rate change is associated with the change of cellulose (I) crystalline structure. Approximate energy of activation has been calculated, from the specific rate constants, between 31 and 40°C. as 10.6 kcal. and between 45 and 50°C. as 16.7 kcal. At other temperatures the determination was handicapped, due to temperature dependence of the order of reaction. An empirical relation between the constants of Sakurada's equation and the reaction temperature has been sought and correlated with the Arrhenius equation. Energies of activation, determined from this relationship, have been found to be very close to the above values. The change of order of reaction with temperature suggests that the reaction is affected by diffusion and the mechanism is interpreted as a diffusion-controlled reaction where hydrogen bonds play a significant role in diffusion.     

Thermodynamic characterization of polyanetholesulfonic acid and its alkaline salts

Experimental and theoretical results for the thermodynamic properties of polyanetholesulfonic acid and its lithium, sodium, and cesium salts in aqueous solution at 298 K are presented. The osmotic pressure was measured using membrane and vapor pressure apparatus in the concentration range c(m) = 0.001-0.30 monomoles/dm(3). The osmotic coefficients obtained from these measurements were low, from 0.2 to 0.45 in this concentration range, indicating a strong interaction between counterions and polyions. The osmotic coefficients of the polyacid and its lithium and sodium salts appeared to be equal within experimental error, but the results for the cesium salt were lower. This indicates a somewhat stronger binding of cesium ions to the polyanion. In addition, enthalpies of dilution, DeltaH(D), from a certain concentration, m(m), to m(m) = 0.0044 monomoles/kg were measured. The measured heats of dilution were exothermic, with the acid producing the strongest and the cesium salt the weakest effect. These results were compared with previously published data for polyelectrolytes of similar structure, namely, polystyrenesulfonic acid and its alkaline salts. The osmotic pressure results indicate that polystyrenesulfonates bind the counterions more strongly than polyanetholesulfonic acid and its salts. Consistent with this finding, the enthalpies of dilution reveal that more heat is released upon dilution of polyanetholesulfonates (stronger exothermic effect) in comparison with the corresponding solutions of polystyrenesulfonic acid in its alkaline salts. These findings can be explained in terms of the structural differences between the two polyions. The experimental results were analyzed in relation to popular electrostatic theories such as the Manning condensation theory and the Poisson-Boltzmann cell model approach, where the polyion is pictured as a uniformly charged line or cylinder. In addition, we performed Monte Carlo simulations for a model polyanetholesulfonic anion having discrete charges. In all of the calculations, the solvent was treated as a continuum with the dielectric constant of pure water under the conditions of measurement. The theoretical considerations mentioned above yield results in semiquantitative agreement with the measured quantities.     

Catalytic activity of mercury salts in certain electrophilic reactions of diketene

Conclusions Mercury salts exert a catalytic effect upon the acetoacetylation of urea, urethane, and dimedon methylenamine, as well as on the reaction of urea with butyraldehyde and carboxylic acid chloride.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 859–863, April, 1967.     

Hydrodynamically induced formation of cellulose fibers. I. Observations on the formation of cellulose fibers from stirred solutions

Like synthetic polymers, a natural polymer such as cellulose may crystallize in fibrous form from stirred solutions. In the present work, it is demonstrated that cellulose fibers can be formed by precipitation from dimethyl sulfoxide/paraformaldehyde solutions by two methods that involve different mechanisms of fiber formation, viz., (A) precipitation of cellulose by addition of nonsolvent to the stirred cellulose solution, and (B) precipitation of cellulose by coagulation of droplets of cellulose solution in a stirred precipitant. Both processes yield fibers with properties depending on the stirring speed and the coagulant strength. The molecular orientation and tensile strength of the fibers produced by method A was low, but increased with the stirring speed, while some fibers formed by method B reached extremely high orientation, depending on the thickness of the fibers. The two mechanisms of fiber formation are discussed on the basis of the experimental observations.     

顺酐均相催化加氢衍生物的研究 Ⅰ.制琥珀酸酐的反应条件优化选择

顺酐均相催化加氢衍生物的研究Ⅰ．制琥珀酸酐的反应条件优化选择刘蒲高润雄刘省明殷元骐１）（中国科学院兰州化学物理研究所兰州７３００００）关键词均相催化加氢顺酐琥珀酸酐钌络合物顺丁烯二酸酐（ＭＡ）是重要的基本有机化工原料，已成为世界上仅次于醋酐和苯酐的第...     

Catalytic activity of bis(dialkylamino)carbenium salts in hydrosilylation reactions

Bis(dialkylamino)carbenium salts {[(Me₂N)₂CCl]⁺}₂MCl₄ ²⁻ (M=Ni, Pd) and {[Me₂NC(X)NR₂]⁺}₂PtCl₆ ²⁻ (R=Me, All; X=H, Cl, Me) are efficient catalysts for hydrosilylation of allyl phenyl ether, triallylamine, allyl chloride, allylamine, and 1-octene with various hydrosilanes. The catalytic activity is dependent on the salt composition and the nature of the metal M, the saturated compound, and the hydrosilane used. The catalysts used are usually insoluble in the reaction mixture, active, and stable. In some cases, carbenium salts are more selective than Speier's catalyst. Novel catalysts, silica-immobilized dialkylaminocarbenium salts, have been prepared. The kinetics of the reaction have been considered. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1041–1044, May, 1997.     

Mechanism of transition between cellulose I and cellulose II during mercerization

It is suggested that the transformation from cellulose I to cellulose II during mercerization is the result of a progressive shift of the sheets of cellulose chains within the crystallites of a microfibril from the quarter-staggered relation in cellulose I to complete correspondence in cellulose II. Qualitatively, the results of such a shift would be consistent with the observed increases in lateral disorder, changes in cell dimensions, swelling, changes in infrared absorption, increases in reactivity of hydroxyl groups and especially with changes in the relative intensities of meridional, x-ray diffraction reflections of cellulose fibers. The consequences of such a shift also include variations of the dihedral angle at the glycosidic linkage to provide an opportunity for the conformational changes which have been deduced from Raman and infrared spectra. Such a shift may take place in the transformation of native celluloses with antiparallel structure as well as those with parallel polarity. It is consistent with and is able to explain examples of “memory” of previous treatment in cellulose samples.     

The dynamics of micelle formation in bile salts I. Sodium cholate and sodium deoxycholate

It has been found that two bile salt solutions of NaC (trihydroxy cholanic salt ) and NaDC (dihydroxy cholanic salt have an excess ultrasonic absorption . This excess absorption fits a single relaxation in all cases . To explain this observed single relaxation the data are considered in terms of several existing models.Simple cation-anion reactions to form a monomer salt are ruled out on the grounds that our experimentations are carried out at concentrations far above the critical micelle concentrations (CMC). A second approach in which the excess absorption is attributed to micelle- counter ion reaction. The third existing model deals with an equilibria between the micelles and the monomers of the bile salts. Three different types of models emerge from this kind of equilibria. Only two (3a and 3b ) of them can be considered as a feasible possibility to explain part of the results.     

Novel cyclic tetraphosphetanes: Molecular and crystal structures of diethylammonium and piperidinium salts of 1,2,3,4-tetramercapto-1,2,3,4-tetrathioxotetraphosphetane

Crystal structures of novel tetrakis(diethylammonium) and tetra(piperidinium) salts of 1,2,3,4-tetramercapto-1,2,3,4-tetrathioxotetraphosphetane are determined by single crystal X-ray diffraction. It is found that the substitution of the piperidinium cation for the diethylammonium one results in a change in the nature of charge distribution in crystals of the compounds, but the nature of supramolecular structures originating from intermolecular hydrogen bonding is preserved. Stoichiometry of the composition and phosphorus-containing anions turn out to be identical in both cases.     

Catalytic reactions of formate. 3. Noble metal chlorides as catalyst precursors for formic acid reactions

Summary Noble metal chlorides (RuCl₃·xH₂O, RhCl₃·3H₂O, PdCl₂ and IrCl₃·xH₂O) have been evaluated as catalyst precursors for the decomposition (HCO₂H H₂ + CO₂), dehydration (HCO₂H H₂O + CO) and air oxidation (2HCO₂H + O₂ 2H₂O + 2CO₂) of 88% HCO₂H at 75–80 °C. RhCl₃ under these conditions is an active oxidation catalyst but not an active decomposition catalyst. However, RuCl₃ is an active decomposition catalyst but not an active oxidation catalyst. PdCl₂ exhibits modest but detectable activity for all three formic acid reactions (decomposition, dehydration and oxidation). IrCl₃ is a relatively active catalyst for all three HCO₂H reactions. A comparison of the catalytic activities of the four noble metal chlorides for HCO₂H decomposition under conditions where both the dehydration and air oxidation reactions are suppressed (4.4% aqueous HCO₂H. Ar atmosphere) indicates the relative catalytic activity sequence: Ir Ru > Pd Rh (inactive).Portions of this work were presented at the 204th National Meeting of the American Chemical Society, Washington, DC, August 1992, paper INOR 124 in abstracts. For part 2 of this series see D. E. Linn Jr, R. B. King and A. D. King Jr, J. Molec. Catal., 80, 165 (1993). 0340-4285.     

Crystallization of bisphenol-A polycarbonate induced by organic salts: Chemical modification of the polymer. I. Model reactions

The chemical modifications induced in diphenyl carbonate (DPC) by sodium arylcarboxylates between 200 and 250°C were studied to model the behavior of bisphenol-A polycarbonate – salt systems. Reaction between the salt and DPC produces sodium phenoxide, the phenyl arylcarboxylate corresponding to the salt, and carbon dioxide. The two latter compounds probably result from the decarboxylation of an unstable intermediate compound, viz., a mixed carboxylic carbonic anhydride. CO₂ and sodium phenoxide act as catalysts transforming DPC into phenyl salicylate via the formation of a small amount of sodium salicylate. Electrophilic acylation of sodium phenoxide by DPC is another possible but minor source of phenyl salicylate. Above 250°C, phenyl salicylate becomes unstable and pyrolyzes into o-phenoxybenzoic acid, which is immedicately esterified in the presence of DPC into phenyl o-phenoxybenzoate. In DPC + sodium o-chlorobenzoate systems, reaction between phenyl o-chlorobenzoate and sodium phenoxide is another source of phenyl o-phenoxybenzoate.     

Gel-permeation chromatographic studies of cellulose degradation. I. Treatment with hydrochloric acid

The molecular weight distribution in various celluloses degraded with hydrochloric acid has been studied by gel-permeation chromatography. Measurements were made on the residue after hydrolysis, on the degradation products solubilized by the acid, and on whole degraded samples comprising the product soluble in the acid plus the residue. It is shown that the total number of crystallites decreases during hydrolysis while the chain length distribution remains constant. The crystallites are gradually broken down into molecular fragments which show a size distribution centered on species with a degree of polymerization of about 8. Possible interpretations of these results are discussed.     

Mass spectrometry of some triphenylcyclopropenium salts. Competition between dimerisation and adduct formation

The triphenylcyclopropenium chloride, bromide and iodide evaporate in the mass spectrometer mainly as the covalent cation-halide adduct, the fluoroborate as the corresponding fluoride adduct and boron trifluoride. In addition di-3,3′-triphenylcyclopropene is formed, presumably via triphenylcyclopropenyl radicals.     

Cobaloxime template reactions I. The formation of N-nitrosamines

The synthesis of a potent carcinogen, N-nitroso-N-methylaniline, employing a bis(dimethylglyoximato)cobaltate template is described. Carbon bonded N-methyleneaniline adducts of cobaloxime with pyridine, NO^-₂ or CN^- in the basal (sixth) coordination position of the cobalt atom were prepared and isolated. These cobaloxime methyleneaniline adducts were found to readily undergo nitrosation when treated with nitrous acid. The resulting N-nitrosamine adducts were characterized by IR, NMR and mass spectroscopy. Interesting trans effects of the basal substituents are noted. Final template reaction products were identified by thermal degradation and chemical cleavage with Cr²⁺.     

The formation of acylimino-derivatives of indoles and pyrroles by reactions with nitrilium salts

$\text{N}$-Methylnitrilium fluoroborates are prepared rapidly by warming trimethyloxonium fluoroborate with a slight excess of the nitrile, subsequent addition of indoles and pyrroles at low temperatures (?50° to ?20°) gives iminium salts (and hence ketones) in high yields.     

2-Benzopyrylium salts. 42. Ortho-quinoid intermediates in recyclization reactions of 2-benzopyrylium salts

The interaction of 1-styryl-substituted 2-benzopyrylium salts with morpholine, methylamine, and malononitrile is highly stereoselective informing cis-3,4-dihydronaphthalenes; this can be taken as evidence that ortho-quinoid intermediates participate in these conversions.For Communication 41, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1468–1475, November, 1991.     

1H-n.m.r. studies on the complex formation ofN,N-dimethylbiuret with alkali and alkaline earth salts

¹H-n.m.r. spectra ofN,N-dimethylbiuret inDMSO containing LiI, LiCl, NaI, KI, RbI, CsI, MgCl₂, CaCl₂, SrCl₂, BaCl₂ and BaI₂ have been investigated. The observed shifts of the NH-signal are relatively stronger than the shifts of the NH₂-signals. At high salt concentration, coalescence of the NH₂-signals and anion effects are observed.

---

¹H-NMR Untersuchungen zur Komplexbildung vonN,N-Dimethylbiuret mit Alkali- und Erdalkalisalzen

Zusammenfassung Protonenkernresonanzspektren vonN,N-Dimethylbiuret inDMSO-Lösungen mit LiI, LiCl, NaI, KI, RbI, CsI, MgCl₂, CaCl₂, SrCl₂, BaCl₂ und BaI₂ wurden aufgenommen. Die beobachteten Verschiebungen des NH-Signals sind stärker als die der NH₂-Signale. Bei höheren Salzkonzentrationen wird Koaleszenz der NH₂-Signale und das Auftreten von Anioneffekten beobachtet.

     

Preparation and novel reduction reactions of vinamidinium salts.

Substituted acetic acids and formamides react in the presence of phosphorus oxychloride to yield the vinamidinium hexafluorophosphate salts 5a-d, 6a-d, and 7 in moderate to good unoptimized recrystallized yields (40-67%) as easily handled nonhygroscopic solids. The 1,3-differentially substituted vinamidinium salts 8 was prepared by amine exchange in 81% yield as are the cyclic diazapinium salts 9 and 10 in > 76% yield. The symmetrical 2-chlorovinamidinium 11 was prepared by displacement of 3 in 71% yield. The 2-chlorovinamidinium salts are cleanly reduced to the parent vinamidinium salts 12-16 using HI or PPh3/pTSA in up to 99% assay yield.