Alkali metal salts of acrylamide C3H4NOM (M = Li,Na, and K): Synthesis and vibrational spectra

Alkali metal salts of acrylamide C₃H₄NOM (M = Li, Na, and K) were synthesized for the first time by metallation of acrylamide with alkali metals, their alkyl derivatives, or hydrides. The structures of the compounds synthesized were studied by Raman and IR spectroscopy. Based on the results obtained, an ionic structure was proposed for the salts. The salts were tested as initiators of the anionic polymerization of acrylamide. The catalytic activity of C₃H₄NOM in the polymerization of acrylamide is not lower than that of the well known catalyst, KOBu¹.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2316–2319, September, 1996.     

季铵盐固相催化使聚氯乙烯脱HCl

通过将季铵盐与聚氯乙烯(PVC)混溶成膜,使其在固相脱HCl,研究了催化剂对PVC脱HCl反应速度和产物结构的影响以及固相反应与温度、时间的关系.发现在催化性能上下基铵盐比乙基铵盐好得多,根据实验结果提出了季铵盐通过分解成叔胺实现催化的机理.     

Reactivity of diazoazoles and azolediazonium salts in <Emphasis Type="Italic">C</Emphasis>-azo coupling reactions

The comparative reactivity of heterocyclic diazo compounds and the corresponding diazonium salts in C-azo coupling reactions was studied using imidazole, pyrazole, and triazole derivatives as examples.The reactivities of pyrazole- and imidazole-derived diazonium salts are much lower than those of thiadiazole- and 1,2,4-triazole-derived diazonium salts but higher than those of pyrrole and indole diazo compounds.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 348–358, February, 2005.     

Thermal degradation studies of alkyl-imidazolium salts and their application in nanocomposites

Increasing the thermal stability of organically-modified layered silicates is one of the key points in the successful technical application of polymer-layered silicate nanocomposites on the industrial scale. To circumvent the detrimental effect of the lower thermal stability of alkyl ammonium-treated montmorillonite, a series of alkyl-imidazolium molten salts were prepared and characterized by elemental analysis, thermogravimetry (TGA) and thermal desorption mass spectroscopy (TDMS). The effect of counter ion, alkyl chain length and structural isomerism on the thermal stability of the imidazolium salts was investigated. Alkyl-imidazolium-treated montmorillonite clays were prepared by ion exchange of the imidazolium salts with Na-montmorillonite. These organically-modified clays were characterized by X-ray diffraction (XRD), TDMS and thermogravimetry coupled with Fourier transform infrared spectroscopy (TGA-FTIR), and compared to the conventional quaternary alkyl ammonium montmorillonite. Results indicate that the counter ion has an effect on the thermal stability of the imidazolium salts, and that imidazolium salts with PF₆⁻, N(SO₂CF₃)₂⁻ and BF₄⁻ anions are thermally more stable than the halide salts. A relationship was observed between the chain length of the alkyl group and the thermo-oxidative stability; as the chain length increased from propyl, butyl, decyl, hexadecyl, octadecyl to eicosyl, the stability decreased. The results also show that the imidazolium-treated montmorillonite has greater thermal stability compared to the imidazolium halide. Analysis of the decomposition products by FTIR provides an insight about the decomposition products which are water, carbon dioxide and hydrocarbons.     

Probing in vitro digestion at oil–water interfaces

Interfacial layers have been widely applied to study the formation and stability of emulsion-based systems. However, the application of isolated interfaces to address digestibility of emulsions is often limited because of the complexity of experimental methods and results. This review summarizes the latest developments in analytical methods and literature data on effects of digestion on interfacial layers. Particular emphasis is given to understand the changes on interfacial magnitudes during oral, gastric, and duodenal digestion, either applied separately or sequentially. Limitations of interfacial aspects and key factors that influence emulsion microstructure in bulk and lipid digestion are identified. Understanding the behavior of interfacial layers upon gastrointestinal digestion promotes an accurate tracking of the physiological fate of emulsions.     

Effect of the reaction state on the polymerization of p-xylenesulfonium salts

1,4-Phenylenebis(methylene) sulfonium salts were polymerized under different conditions to yield p-xylylene sulfonium salt polyelectrolytes in a broad range of molecular weights. The aqueous reaction mixture formed a reversible gel at initial monomer concentrations higher than 1.0M, but at lower concentrations it remained as an emulsion until reaction completion. The effect of reaction time on intrinsic viscosities and polymer yields for both the emulsion and the gel state is discussed. The higher yields obtained when the reaction was carried out in the presence of a water-immiscible organic solvent were apparently due to the effect of this solvent on increasing the concentration of the reactive intermediate that led to the polyelectrolyte. Both the addition of an organic solvent and the variation of the initial monomer concentrations allowed some control over the molecular weight of the polyelectrolyte formed.     

Interaction of sodium cholate with dioctadecyldimethylammonium chloride vesicles in aqueous dispersion

Mixtures of dioctadecyldimethylammonium chloride (DODAC) cationic vesicle dispersions with aqueous micelle solutions of the anionic sodium cholate (NaC) were investigated by differential scanning calorimetry, DSC, turbidity and light scattering. Within the concentration range investigated (constant 1.0 mM DODAC and varying NaC concentration up to 4 mM), vesicle → micelle → aggregate transitions were observed. The turbidity of DODAC/NaC/water depends on time and NaC/DODAB molar concentration ratio R. At equilibrium, turbidity initially decreases smoothly with R to a low value (owing to the vesicle–micelle transition) when R = 0.5–0.8 and then increases steeply to a high value (owing to the micelle–aggregate transition) when R = 0.9–1.0. DSC thermograms exhibit a single and sharp endothermic peak at T_m ≈ 49 °C, characteristic of the melting temperature of neat DODAC vesicles in water. Upon addition of NaC, T_m initially decreases to vanish around R = 0.5, and the main transition peak broadens as R increases. For R > 1.0 two new (endo- and exothermic) peaks appear at lower temperatures indicating the formation of large aggregates since the dispersion is turbid. All samples are non-birefringent. Dynamic light scattering (DLS) data indicate that both DODAC and DODAC/NaC dispersions are highly polydisperse, and that the mean size of the aggregates tends to decrease as R increases.     

Novel Lewis-base ionic liquids replacing typical anions

We have synthesized two kinds of new Lewis-base ionic liquids (ILs); one is based on the relatively strong Lewis basic acetate anion, and the other is a salt composed of a mono-alkylated diamine such that the Lewis base site is incorporated in the cation. 1-Octyl-4-aza-1-azonia-bicyclo[2.2.2]octane bis(trifluoromethanesulfonyl)amide, [C₈dabco]TFSA, and N-butyl-N-methylpyrrolidinium acetate, [p_1,4]OAc, melted into fluid liquids at 26 and 81 °C, respectively. The thermal decomposition of [p_1,4]OAc started at around 150 °C, whereas the thermal stability of [C₈dabco]TFSA was almost equal to that of typical TFSA-based ILs in spite of the Lewis base site. This suggests that if the Lewis base site is incorporated into the cation the IL can maintain higher thermal stability. In addition, as a further result of the presence of the basic nitrogen, [C₈dabco]TFSA can dissolve hydrated Cu(NO₃)₂ whereas the other TFSA-based ILs cannot.     

Oxidation-Reduction Conversions of Derivatives of 1,4-Dihydropyridine and 4H-pyran on Interaction of Alicyclic 1,5-Diketones wth 4-Aminoazobenzene

The interaction of 2,2'-methylenedicyclohexanone and 2,2'-methylenedicyclopentanone with 4-aminoazobenzene in acetic acid leads to reduction of the azo group of 1,4-dihydropyridine and 4H-pyran derivatives formed as intermediates. The reduction products were isolated as the corresponding pyridinium salts.     

Alkylation of salts ofN-nitrohydroxylamines with chloromethylnitramines

The reactions of Ag-salts ofN-nitmhydroxyumines withN-methyl-N-chloromethylnitramine afford mainly products ofO-alkylation, whereas the reactions of the corresponding Li-, Na-, K-, Mg-, and NH₄-sals in the presence of tetrabutylammonium (TBAB) give mainly products ofN-alkylation. The reactions of the corresponding. NH₄-salts with bis-(chloromethyl)nitramine in the presence of TBAB lead solely to products ofO-alkylation. Increasing in the amount of TBAB results in the appearance of theN-isomer.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1740–1744, July, 1996.