共查询到20条相似文献,搜索用时 78 毫秒
1.
T. V. Stupnikova B. P. Zemskii R. S. Sagitullin A. N. Kost 《Chemistry of Heterocyclic Compounds》1982,18(3):217-232
Methods for the preparation of anhydro bases of the pyridine series by deprotonation of the corresponding quaternary salts under the influence of bases, as well as by the direct reaction of quaternary pyridinium or halopyridinium salts with CH acids in the presence of bases, are examined. The reactions of anhydro bases with various reagents (alkyl cations, acylium cations, the proton, aldehydes, isothiocyanates, carbon disulfide, the hydroxide ion, etc.), which constitute evidence for their high reactivities, are examined. The participation of anhydro bases as intermediates in many reactions intended for the preparation of new heterocyclic systems is demonstrated.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.3, pp. 291–311, March, 1982. 相似文献
2.
Satoshi Kaneco Kenji Iiba Hideyuki Katsumata Tohru Suzuki Kiyohisa Ohta 《Journal of Solid State Electrochemistry》2007,11(4):490-495
The electrochemical reduction of CO2 with a Cu electrode in methanol was investigated with sodium hydroxide supporting salt. A divided H-type cell was employed;
the supporting electrolytes were 80 mmol dm−3 sodium hydroxide in methanol (catholyte) and 300 mmol dm−3 potassium hydroxide in methanol (anolyte). The main products from CO2 were methane, ethylene, carbon monoxide, and formic acid. The maximum current efficiency for hydrocarbons (methane and ethylene)
was 80.6%, at −4.0 V vs Ag/AgCl, saturated KCl. The ratio of current efficiency for methane/ethylene, r
f(CH4)/r
f(C2H4), was similar to those obtained in LiOH/methanol-based electrolyte and larger relative to those in methanol using KOH, RbOH,
and CsOH supporting salts. In NaOH/methanol-based electrolyte, the efficiency of hydrogen formation, a competing reaction
of CO2 reduction, was suppressed to below 4%. The electrochemical CO2 reduction to methane may be able to proceed efficiently in a hydrophilic environment near the electrode surface provided
by sodium cation. 相似文献
3.
Krystian Pluta 《Journal of heterocyclic chemistry》1992,29(6):1599-1603
Reactions of thioquinanthrene 1 with sodium alkanethiolates or S-alkylisothiouronium salts (in the presence of sodium hydroxide) at 70° in DMSO or DMF yielded 4,4′-dialkylthio-3,3′-diquinolinyl sulfides 3 , which were results of the S-S type of the Smiles rearrangement of primary reaction products - sodium 3-quinoline-thiolates 6. When the reactions were carried out at 20° the products were 3′,4-dialkylthio-3,4′-diquinolinyl sulfides 2. 相似文献
4.
Binita SutharAnuar Aldongarov Irina S. IrgibaevaMitra Moazzen Bernadette T. Donovan-MerkertJon W. Merkert Thomas A. Schmedake 《Polyhedron》2012,31(1):754-758
Various salts of tetracationic tris(2,2′-bipyridine)silicon(IV) and bis(2,2′;6′,2″-terpyridine)silicon(IV) were synthesized by reaction of SiI4 with the appropriate ligand followed by metathesis reactions. The resulting salts exhibit multiple, chemically reversible one-electron reduction waves that are significantly shifted to less negative reduction potentials than the corresponding ruthenium analogs. The salts also exhibit anion dependent ion pair charge transfer bands throughout the visible spectrum. Weak, low energy emission is observed from Si(bipy)3Br4 and Si(terpy)2Br4 in the solid state at 77 K when the sample is excited in the ion pair charge transfer band. 相似文献
5.
S. Musić G. Štefanić N. Vdović A. Sekulić 《Journal of Thermal Analysis and Calorimetry》2000,59(3):837-846
Zirconium hydroxide particles produced by rapid precipitation at pH 10.4, 7 or 2 were subjected toγ-irradiation up to a final
dose of 20 MGy. The effects of the γ-irradiation were examined by X-ray powder diffraction, laser Raman spectroscopy, differential
scanning calorimetry and microelectrophoretic measurements. It was found that γ-irradiation had no influence on the behaviour
of zirconium hydroxide during calcination and subsequent cooling. The results of microelectrophoretic measurements showed
that γ-irradiation influences the surface properties of zirconium hydroxide as a function of the precipitation pH. Zirconium
hydroxide precipitated at pH 2 proved to be the most susceptible to γ-irradiation, while the sameγ-irradiation had very little
(if any) effect on the surface properties of zirconium hydroxide precipitated at pH 10.5. After γ-irradiation, the electrophoretic
mobility of zirconium hydroxide precipitated at pH 2 was increased at both low and high pH, thereby indicating an increase
in its adsorption capacity. The analogy observed between the pH-dependence of the effects of γ-irradiation on the electrokinetic
behaviour of zirconium hydroxide and the influence of ball-milling on the thermal behaviour of zirconium hydroxide [8] suggested
that the susceptibility of amorphous zirconium hydroxide increases with decrease of the precipitation pH.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
The reactions of 2-phenyl-1,3-benzoxathiolium perchlorate with common nucleophilic reagents (water, sodium hydroxide, ethanol, thiophenol, morpholine, phenylmagnesium bromide), with reducing agents (zinc, lithium aluminium hydride) and with manganese dioxide, were studied. In every case the reactions proceed by attack of the reagents at the C-2 position of the cationic system, giving rise either to 1,3-benzoxathiole derivatives or to ring-opening products. The 1,3-benzoxathiolium salts were shown to be suitable intermediates for converting the carboxylic acids into aldehydes and ketones. 相似文献
7.
Oligoethylene glycol substituted imidazolium salts were synthesized as promoters for a range of SN2 reactions, and their efficiency was examined. These tailor-made organic promoters enhanced the nucleophilicity of alkali metal salts significantly through the combined effects of two promoters (oligoethylene glycols and imidazolium salts) in a single molecule. The effects of the oligoethylene glycol side chain length, ionic liquid anions, nucleophiles, and substrates were investigated systematically. [hexaEGmim][OMs] and [dihexaEGim][OMs] showed the highest efficiency for SN2 reactions using alkali metal salts. The role of the terminal hydroxyl groups of the oligoethylene glycol moiety was assessed by examining the relative SN2 yields of chlorination and bromination. The results showed that the hydrogen bonding strength of the hydroxyl groups with the nucleophile is very important. The mechanism for the excellent promotion of SN2 reactions by oligoEGILs was examined by quantum chemical calculations. The results showed that the oxygen atoms in the oligoethylene glycol portion and the ionic liquid anion act on the counter cation K+ or Na+ as a Lewis base, to enhance the reactivity of the metal salts significantly. 相似文献
8.
Farid Ibrahim El-Dossoki 《Fluid Phase Equilibria》2011,305(2):161-168
Liquid-liquid equilibrium (LLE) measurements for aqueous systems containing some pentanols and sodium, or potassium nitrate have been performed experimentally at 25 °C and atmospheric pressure. The pentanols are: 1-pentanol (1P), 2-pentanol (2P), 3-pentanol (3P), 2-methyl-1-butanol (3M1B) and 2-methyl-2-butanol (2M2B). The obtained data have been modeled using an extended UNIQUAC activity coefficient model. The influence of the cation, the anion and the temperature on the liquid-liquid equilibrium, are illustrated by applying the Setschenow equation on the studied systems and on other systems from literature. The results show that the influence of sodium salts is higher than that of potassium salts with the same anion and the same alcohol. On the other hand, the influence of the nitrate and bromide salts is lower than that of chloride salts with the same cation and the same alcohol. Linearity of Setschenow relation indicates that the influence of the given salts on the liquid-liquid equilibrium in the systems under study, are additive. The effect of temperature on the phase behavior is that the mutual solubilities of both liquids, in the presence of salt, decrease with temperature. 相似文献
9.
Silica and sodium acetate are present in the steam generator tube sheet crevices of many nuclear power plants. Trace solutes in the condensate are tremendously concentrated in the crevices by boiling. Sparingly soluble sodium silicates and other solids precipitate from the crevice liquid leaving an extremely concentrated molten mixture of water, sodium acetate and other salts. The precipitates buffer the activity of sodium hydroxide in the superheated liquid that remains. The activity of NaOH corresponding to the buffers quartz/sodium disilicate and sodium disilicate/sodium metasilicate at 317°C has been determined experimentally. The sodium hydroxide content of a sodium acetate-water melt buffered by these reactions was determined bychemical analysis, and the corresponding activity of NaOH at temperature was calculated using the recently published Pitzer-Simonson Model of molten salt-water mixtures. The molten mixture of sodium acetate and water plays the role of solvent in these experiments and calculations. The free energies of formation of solid sodium silicates at 317°C were also determined. The activity of NaOH corresponding to other silicate and phosphate buffers was calculated using published thermodynamic data and estimated from phase diagrams. 相似文献
10.
Michael J. Blandamer John Burgess Philip P. Duce Keith S. Payne Robert Sherry Paul Wellings Martyn V. Twigg 《Transition Metal Chemistry》1984,9(5):163-173
Summary Kinetics of nucleophilic substitution at a range of low-spin iron(II)diimine complexes have been examined in the presence of a variety of salts, to probe the role of hydroxide and cyanide as nucleophiles and of other ions in ion association equilibria. Equilibrium constants for interaction of hydroxide and of cyanide with many of these ligands, free or complexed with iron(II) or molybdenum(0), have been measured, in water and in binary aqueous solvent mixtures. Effects of solvent, temperature, and pressure on rate constants and on equilibrium constants have been monitored for selected systems. In the light of these results, and of ancillary qualitative observations, we discuss the role and nature of intermediates in nucleophilic substitution reactions of transition metaldiimine complexes. 相似文献
11.
12.
W.H. Saunders S.D. Bonadies M. Braunstein J.K. Borchardt R.T. Hargreaves 《Tetrahedron》1977,33(13):1577-1580
Tracer studies with β-deuterated sulfonium salts have shown that the α'-β, or ylid mechanism can be the major path of elimination in the reaction of sulfonium salts with t-butoxide in t-butyl alcohol, while the E2 reaction is dominant with hydroxide in water or n-butoxide in n-butyl alcohol. The structure of the sulfonium salt also affects the propensity toward α'-β elimination, with 3-pentyl > 3-propyl and eyclopentyl > 3-pentyl > cyclohexyl. The S-methyl protons of the sulfonium salt exchange at a rate much faster than that of the elimination reaction. A strongly basic medium and a syn-periplanar arrangement of the α-C-S and β-C-H bonds seem to be the two most important factors favoring the α'-β mechanism. 相似文献
13.
The behavior of the copper (II) salts of the a-isomers of some acyloin oximes towards a series of selected amines was examined in order to study the unusual solubility relationships which these copper salts exhibit towards ammonium hydroxide. The insolubility in ammonium hydroxide of these copper salts of acyloin oximes has been attributed to their being inner complex salts. Evidence is presented which is contra y to this view. Based on the solubilities of the copper (II) salts investigated, a polymeric structure for copper (II) acyloin oximes is proposed. The study included the following α-isomers of acyloin oximes: benzoin oxime, 2,2'-furoin oxime, phenylbenzoin oxime, methylbenzoin oxime, 2,2'thenoin oxime, a-hydroxyisobutyrophenone oxime, and α-hydroxyacetophenone oxime. The last four compounds had not been examined previously as to their ability to form copper (II) salts. 相似文献
14.
Ming-Wu Ding Wen-Jing Xiao Shui-Ming Lu Wen-Fang Huang De-Qing Shi Tian-Jie Wu 《Heteroatom Chemistry》1997,8(2):191-197
ω-Azolylalkenes 3, 4, and 5 were synthesized by N-alkylation of C-alkylation of ω-bromoalkenes 2, which were obtained either by phase transfer Wittig reactions of ω-bromoalkylphosphonium salts 1 with aldehydes or by Wittig reactions of ω-hydroxyalkylphosphonium salts 6 with aldehydes and subsequent bromination. ω-Azolylalkenes 3 were also directly prepared by the Wittig reaction of ω-azolylalkyltriphenylphosphonium salts 8 with aromatic aldehydes. The stereochemistry of these Wittig reactions was studied. © 1997 John Wiley & Sons, Inc. 相似文献
15.
Arenediazonium tosylate salts have been successfully employed as a new and efficient reagent in halogenation reactions. A novel and economic protocol has been developed for the bromination and chlorination of various anilines using arenediazonium tosylate salts. A wide variety of reaction conditions were studied in acetonitrile at either room temperature or 60 °C in the presence or absence of catalyst with good to excellent yields. A surprising result showed the formation of acetanilides as a major product of aniline and methyl-substituted aniline halogenations in high yields. 相似文献
16.
A novel mode of base-induced decomposition of N-alkoxypyridimum salts carrying a β-hydrogen in their alkoxy chain is described. In these compounds the N-oxide moiety can act as a leaving group in an elimination reaction yielding an ethylenic derivative, in competition with the classical decomposition to aldehyde and pyridine. This latter is predominant in salts 9 and 10 bearing a methyl group in 2 or 6 positions of the pyridine nucleus, whereas the new mode of decomposition becomes almost exclusive for salts 7 and 8 unsubstituted in these positions. Deuteration studies show that proton abstraction does not occur by transfer to an ylide during the decomposition by hydroxide ion, proton abstraction results from direct attack by hydroxide ion except for the α-proton of salts bearing at least one methyl group in 2 or 6 positions where it occurs by a transfer (essentially intramolecular) to an intermediary anhydrobase. 相似文献
17.
Jaroslav Kví?ala Michal Beneš Old?ich Paleta Vladimír Král 《Journal of fluorine chemistry》2010,131(12):1327-1337
2,3,4,5,6-Pentafluorobiphenyl (PFBi) was modified by the nucleophilic substitution of one fluorine using a series of O-, S- and N-nucleophiles, viz. alkaline salts of 2,2,2-trifluoro-ethanol, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctanol, 1,2;3,4-di-O-isopropylidenexylitol, allylsulfane, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctane-1-thiol, 3-aminopropan-1-ol (7), and tert-butyl N-(3-aminopropyl)carbamate (8). All the substitutions took place exclusively at the position para to the phenyl group. (3-Amino-propyl)amino derivative of PFBi (15) was further modified at the terminal amino group by acylation or fluoroalkylation. The reaction of 8 was applied to meso-5,10,15,20-tetrakis-(pentafluorophenyl)porphyrin (20) to afford tris- (21) and tetrakis-substituted (22) products with complete para-regioselectivity. Theoretical studies of the reaction pathways of PFBi with ammonia, microsolvated lithium fluoride or lithium hydroxide revealed that no Meisenheimer-type intermediates are formed in the course of the simulated reactions: instead, tetrahedral SN2 mechanism was found. Significant regioselectivity of the nucleophilic aromatic substitution, leading to 4-substituted products, was predicted based on relative transition state energies in agreement with the observed experimental results. 相似文献
18.
A novel measure of the purity of soluble salts is being proposed: The pH of saturated aqueous solutions at 25°, called “equi-adsorption point”. It is obtained from reagent grade salts, with repeated recrystallisations in double distilled water under free access of atmospheric CO2. Salt preparations, which are not brought to their equi-adsorption points can give saturated solutions of rather differing pH-values. The double system salt/H2O can be regarded as synclinal curve of the corresponding triple system, the alkaline oxide (hydroxide), acid and water. It can be shown that the equiadsorption point follows from the relative salting out effect of the hydroxide, or acid upon the water solution. It is of practical value as an objective measure of the purity of salts with respect to H+ or OH?. The usual quotations of pH-values of diluted solutions as characteristic for the purity of salts are not supported. 相似文献
19.
J. A. Van Allan G. A. Reynolds C. C. Petropoulos 《Journal of heterocyclic chemistry》1972,9(4):783-787
4-Aminopyrylium derivatives were prepared from secondary amines and 4-methoxy-2,6-dimethylpyrylium perchlorate ( 1a ) and the corresponding 2,6-diphenyl derivative. Excess amine or elevated temperature resulted in the addition of two equivalents of amine to 1a . The reactions of the aminopyrylium salts with hydroxide, ammonia, primary amines, hydrazines, cyanoacetamides, ethyl cyanoacetate, malononitrile, nitromethane, sodium sulfide, and a Grignard reagent are described. 相似文献
20.
Jaime GonzálezVíctor M. Pérez David O. JiménezGermán Lopez-Valdez David CoronaErick Cuevas-Yañez 《Tetrahedron letters》2011,52(27):3514-3517
Temperature is an important factor in the copper catalyzed alkyne azide cycloaddition under oxidative conditions. 1,2,3-Triazoles were obtained in high yields when several alkynes and azides were reacted at methanol reflux using catalytic amounts of both copper iodide and sodium hydroxide. On the other hand, bistriazoles were major products when reactions were performed at −35 °C using excess sodium hydroxide. 相似文献