Adsorption of quaternary ammonium chlorides with various hydrocarbon chain lengths to glass

Contact angles, measured with various liquids, have been employed to calculate the surface free energies of glass after adsorption of quaternary ammonium chlorides with a variable hydrocarbon chain length 8n16. The thickness of the adsorbed layers has been determined ellipsometrically. A clear relation is observed between the measured parameters and the hydrocarbon chain lengthn, if only the extremesn=8 andn=16 are considered. Surface free energies decrease from 138 erg.cm^–2 for clean glass to 101 and 64 erg.cm^–2 forn=8 andn=16, respectively, at the highest concentration tested (7.5 mM). The adsorbed layer thickness of C₈ amounts to approximately 50 % of the thickness observed for C₁₆. No clear relation between the measured parameters is observed for the intermediate hydrocarbon chain lengths, which presumably reflects the many configurations possible in these adsorbed layers. It is envisaged that adsorption of C₈ as well as C₁₆ is restricted to a monolayer, which is completed at approximately 2 mM. In the case of C₈ electrostatic repulsion between the polar headgroups will inhibit further adsorption, whereas in the case of C₁₆ the van der Waals attraction from the adsorbed layer and the glass will probably not be sufficient to stimulate further adsorption.     

Synthesis and biological activities of some homopiperazine quaternary ammonium

将蜂王酸经醋酐酯化后与1-甲基高哌嗪发生酰化后再季铵化,合成了8个未见文献报道的高哌嗪类季铵盐4a～4h,所有化合物的结构经IR,1H NMR,13C NMR和MS分析确认.考察了这些化合物与乙酰胆碱酯酶(AchE)、丁酰胆碱酯酶(BuchE)、金黄色葡萄球菌的抑制作用,结果表明:化合物4对AchE和BuchE具有较好的抑制活性,其中4c对AchE的抑制效果最好,其IC50 =2.56 μmol/L;4g对BuchE的抑制效果最好,IC50 =6.62 μmol/L;化合物4e,4h在浓度为0.25g/L时对金黄色葡萄球菌(Staphylococcus aureus)的抑菌效果较好.     

Polymerization of amphiphilic quaternary ammonium salts of acrylic,methacrylic, and ethacrylic acids

The polymerization behavior of dodecyltri-methylammonium methacrylate, and hexadecyltrimethylammonium acrylate, methacrylate and ethacrylate as amphiphilic monomers bearing a polymerizable double bond outside the micelle shell was investigated in micellar solution. Although the monomers did not have spontaneous polymerizability, they polymerized in the presence of both oil-soluble and water-soluble radical initiators, in spite of the difference of the expected location solubilizing initiator molecules. The profit based on micelle-forming of the monomer on the polymerization in water disappeared by the addition of sodium chloride into the polymerizing system due to the increased dissociation between cationic micelles and the polymerizable counter ions.     

Chemical ionization desorption mass spectrometry of some quaternary ammonium salts

The ammonia chemical ionization desorption spectra of N,N-dimethyl quaternary ammonium iodides in addition to high protonated molecular ion [M + H]⁺ intensity, show signals for an ion radical composed of N-methyl abstracted salt cation and ammonia [C + NH₃? CH₃]^+˙. These ions corresponding to the cation +2 show increased importance in the chemical ionization mode, using the same reagent gas. The technique of chemical ionization desorption appears suitable for the analysis of salts, and thus for the determination of the molecular weight of both anion and cation.     

Self association of some quaternary ammonium and phosphonium salts in benzene

From the dependence of the molal osmotic coefficients of (hept)₄NX (X = Cl, Br, J), (hept)₄NNO₃ and (oct)₄PNO₃, in benzene at 33, 40 and 50°C, on the solute concentration, the dimerization constants of solute ion-pairs and the corresponding thermodynamic functions of dimerization, ΔG°, ΔH° and ΔS° have been calculated. The thermodynamic data are discussed in terms of a simple electrostatic model of association.     

Mimicking the behaviour of rigid rod molecules. Smectic H liquid crystals from amphiphilic quaternary ammonium salts

The effect of secondary hydrogen-bonding interactions on the crystalline and liquid crystalline phases of quaternary ammonium salts functionalised with a carboxylic group attached at the polar head through a decyl spacer of a homologous series of N-alkyl-N-carboxydecyl-N,N-dimethylammonium bromides was investigated by polarising optical microscopy, differential scanning calorimetry and X-ray diffraction. The low-temperature crystal phases were found to have a lamellar structure in which the ammonium bromide groups are arranged within the layers in two distinct planes, alternately separated by single layers of alkyl chains and double layers of carboxydecyl chains coupled through the carboxyl end groups. At higher temperatures, although these molecules were made from soft flexible chains, smectic H mesophases were identified. The smectic layers were found to be formed by the same two ionic planes alternately separated by the alkyl and carboxydecyl sub-layers. The smectic structure was compared with the three-dimensional positional order observed in the smectic T phase of dihydroxyl functionalised quaternary ammonium salts already described in the literature.     

Utility of quercetin for determination of some tertiary amine and quaternary ammonium salts

A simple and sensitive spectrophotometric method for the assay of eight drugs containing quaternary ammonium or tertiary amine moieties is described. The method is based on the interaction of these drugs with quercetin after its oxidation with N-bromosuccinimide (as counter ion) to give highly colored ion-pairing complexes extractable with organic solvents. The absorbances of the colored complexes are measured in the range of 528-560 nm. Beer's law is obeyed for the studied drugs in the range 5-30 mug ml(-1). The method is successfully applied to the analysis of the studied drugs in commercial dosage forms.     

Micellization of dodecyldimethylethyl- ammonium bromide in aqueous solution

Specific conductivity of aqueous solutions of dodecyldimethylethylammonium bromide has been determined in the temperature range of 15-40°C. The critical micelle concentration (cmc) and ionization degree of the micelles, b, were determined from the data. Thermodynamic functions, such as standard Gibbs free energy, ΔG _m°, enthalpy, ΔG _m°, and entropy, ΔG _m°, of micellization, were estimated by assuming that the system conforms to the mass action model. The change in heat capacity upon micellization, ΔG _m°, was estimated from the temperature dependence of ΔG _m°. An enthalpy-entropy compensation phenomenom for the studied system has been found. This revised version was published online in July 2006 with corrections to the Cover Date.     

Studies on extraction of iron(III) and cobalt(II) chlorides by quaternary ammonium halides

Summary The extraction of iron(III) and cobalt(II) from hydrochloric acid solutions by Hyamine 1622, a quaternary ammonium halide, in dichloroethane is described. The effect of acidity, salting-out agent, metal and extradant concentrations and temperature, has been investigated. The extraction mechanism is discussed in the light of results obtained. Separation of iron(III) and cobalt(II) is also outlined.     

Microwave synthesis of quaternary ammonium salts

The microwave synthesis of several quaternary ammonium salts is described. The synthesis provides comparable or better yields than published methods with reduced reaction times and in the absence of solvent.     

Solid-phase extraction of quaternary ammonium herbicides

This paper highlights recent advances in the solid-phase extraction (SPE) of quaternary ammonium herbicides in water, soil, plant and biological samples. After a brief introduction summarizing the properties of quaternary ammonium herbicides and the difficulties involved in measuring them, attention is paid primarily to solid supports used for isolation and concentration, pre-treatments required for the different matrices, and eluents applied for quantitative desorption of these analytes. The determination techniques used after SPE and applications of the proposed SPE methodology are also briefly discussed.     

1-(Aziridine) carbonyl chlorides and 1-(aziridine) carbonyl quaternary ammonium chlorides. Rearrangement to 2-(chloroalkyl) isocyanates

Aziridine reacted with phosgene in the presence of an acid acceptor or with 1,1′-carbonylbis(pyridinium) chloride to produce 1-(aziridine)carbonyl chloride (XII) or 1-(aziridine)carbonyl pyridinium chloride (XIII), respectively, as transient intermediates. Attempts to trap and observe (XII) and (XIII) at -10° were unsuccessful. These elusive materials underwent facile rearrangements to 2 - chloroethyl isocyanate under these conditions. Aziridine reacted with 1,1′-carbonylbis(triethylammonium)chloride (VII) at -20° to give 1-(aziridine) carbonyl triethylammonium chloride (X) as a transient intermediate which proceeded to 2-chloroethyl isocyanate. At -10° this reaction produced N,N-diethyl-1-aziridinecarboxamide. Aziridine reacted with a large excess of phosgene in the absence of an acid acceptor to give N-2-(chloroethyl) carbamoyl chloride (III), 1,1′-bis(2-chloroethyl) urea (IV) and 2-(β-chloroethylamino)-2-oxazoline hydrochloride (V). Possible mechanisms for these reactions are discussed.     

Crystal lattice energy of ammonium and methanaminium chlorides

The fraction of crystal lattice energy of ammonium and methanaminium chlorides caused by electrostatic interactions has been evaluated on the basis of modified Coulomb equation for infinite number of interacting charges using available crystallographic information and estimating charge distribution for cations by MNDO and INDO methods. The evaluated characteristics compare well with experimentally derived crystal lattice energies particularly with respect to the observed trends of both quantities on the degree of substitution.

---

Zusammenfassung Unter Verwendung zugänglicher kristallographischer Informationen und einer Schätzung des Ladungsbeitrages von Kationen (MNDO, INDO) wurde auf der Basis einer modifizierten Coulomb-Gleichung für eine unendliche Zahl von beteiligten Ladungen derjenige Anteil der Kristallgitterenergie von Ammonium- und Methanaminiumchloriden geschätzt, der auf elektrostatischen Wechselbeziehungen beruht. Die geschätzten Angaben stimmen gut mit experimentell ermittelten Kristallgitterenergien überein, besonders im Hinblick auf die beobachtete Tendenz beider Größen in Abhängigkeit vom Substitutionsgrad.

     

Inclusion of quaternary ammonium compounds by calixarenes

In weakly polar solvents, strong association occurs between calixarene anions and tetraalkylammonium cations, with the magnitude of the observed equilibrium constants depending upon the charge on the anion, the solvent, the ring size of the calixarene and the nature of the alkyl group of the cation. Large upfield shifts of the methyl resonances of the [(CH₃)₄N]⁺ cation in solutions of [(CH₃)₄N]₂[p-t-butylcalix[6]arene-2H] indicate cation inclusion in a structure which is possibly identical with that found for the solid salt by X-ray crystallography. This shows one of the cations to be included within a partial cone structure of a hinged 3-up, 3-down conformation of the calixarene. The functionalised tetramethylammonium ions, choline and acetyl choline, are also strongly included by various calixarene anions but attempts to detect significant modification of the reactivity of acetyl choline resulting from inclusion have not been successful.This paper is dedicated to the commemorative issue on the 50th anniversary of calixarenes.