Novel ions of quaternary ammonium halides in FDMS

Field desorption mass spectrometry exhibited novel ions [ Y-n H+n R ]+and [ Y-nH+nX]+as well as cluster ions [nY+(n-1)X-mH+mR]+and [nY+( n-1)X-mH+mX]+(n,m=0-3; X and Y represent the cation and anion moieties of quaternary ammonium halides),whose formation mechanism was discussed.     

Potentiotitrimetry of anions using quaternary ammonium halides: An overview

An overview of the analytical applications of quaternary ammonium halides is presented. These compounds are used as titrants in the potentiometric determination of a large number of inorganic and water-soluble organic anions. Topics discussed are titrants, electrodes, inorganic and organic applications, unusual stoichiometrics, and possible separations.     

Thermal stability of quaternary ammonium hexafluorophosphates and halides

Thermal decomposition of hexafluorophosphates of short-chain tetraalkylammonium salts of the general formula R₃R’NPF₆, where R₃ = R’ = CH₃, C₂H₅, C₄H₉; R₃ = C₂H₅, R’ = CH₂C₆H₆ or CH₂CH=CH₂, was studied by thermal gravimetric analysis. Measurements were performed in air in the temperature interval 20–500°C. The thermal stability of halides with the same cations in the same temperature interval was studied for comparison. The effect of cation on the thermal stability of the halides and hexafluorophosphates was examined. The mechanism of thermal decomposition of quaternary ammonium hexafluorophosphates was suggested.     

The adsorption of quaternary ammonium salts at a mercury solution interface: Part II. Non-symmetrical quaternary ammonium salts

The adsorption of triethyl alkyl (and allyl) ammonium bromides on a mercury electrode has been investigated. The isotherms and values of the free energy of adsorption yield information on the mode of adsorption of the cations. The formation of partial bimolecular films on the surface of mercury by the cations studied has been described and a simple explanation put forward concerning the mechanism of destruction of these films.     

Analytical applications of quaternary ammonium halides using ion-selective electrodes: A review

Summary The analytical applications of quaternary ammonium halides are reviewed. These compounds are used as titrants in the potentiometric determination of a variety of inorganic and organic anions including soaps and surfactants. Various liquid-membrane electrodes such as the perchlorate, fluoroborate, nitrate, and calcium electrodes may be used as sensors and, in some cases, solid-state electrodes such as the cyanide (iodide) electrode. The most important titrants are cetyltrimethylammonium bromide and chloride and cetylpyridinium chloride.

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Analytische Anwendungen von quaternären Ammoniumhalogeniden mit Hilfe von ionen-selektiven Elektroden. Ein Überblick

Zusammenfassung Quaternäre Ammoniumhalogenide werden als Titrationsmittel bei der potentiometrischen Bestimmung vieler anorganischer und organischer Anionen, einschließlich von Seifen und oberflächenaktiven Substanzen, verwendet. Verschiedenartige Flüssig-Membran-Elektroden (Perchlorat-, Fluorborat-, Nitrat- und Calciumelektroden) können als Sensoren benutzt werden. Auch Fest-Elektroden (Cyanid, Iodid) kommen in bestimmten Fällen zum Einsatz. Die wichtigsten Titranten sind Cetyltrimethylammoniumbromid und -chlorid sowie Cetylpyridiniumchlorid.

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Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48

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Parts of this paper were presented at the Anorganisch-Chemisches Institut I der Universität, Frankfurt/Main, on April 23, 1981     

Aggregation behavior of nitrophenoxy-tailed quaternary ammonium surfactants

Cationic surfactants N,N,N-trimethyl-10-(4-nitrophenoxy)decylammonium bromide (N10TAB) and N,N,N',N'-tetramethyl-N,N'-bis[10-(4-nitrophenoxy)decyl]-1,6-hexanediammonium dibromide (N10-6-10N), bearing aromatic nitrophenoxy groups in the ends of their hydrophobic chains, have been synthesized, and their self-assembling properties in aqueous solutions have been studied by conductivity, isothermal titration microcalorimetry, 1H NMR spectroscopy, and dynamic light scattering. Below the critical micelle concentration, N10-6-10N can form premicelles with 2 or 3 surfactant molecules. Beyond the critical micelle concentration, the two surfactants have strong self-aggregation ability and can form micelles of rather small size and with small aggregation numbers N, which are 30 +/- 3 for N10TAB and 20 +/- 2 for N10-6-10N, respectively. Also, the variations in 1H NMR signals at different surfactant concentrations provide the information on the environmental change of the surfactants upon their micellization progress. The most prominent phenomenon is the shielding effect of the aromatic groups over the protons in the aliphatic chains, implying that the nitrophenoxy groups partially insert into the micelles and face the several middle methylenes of the hydrophobic side chains.     

Microtitration of various anions with quaternary ammonium halides using solid-state electrodes

Many solid-state electrodes were found to respond as endpoint detectors in the potentiometric titration of large inorganic and organic anions with quaternary ammonium halides. The best response was obtained with the iodide and cyanide electrodes although practically any electrode can function as endpoint sensor. The titrants were hexadecylpyridinium chloride and hexadecyltrimethylammonium chloride; hexadecyltrimethylammonium bromide and Hyamine 1622 may also be used. Some inorganic anions thus titratable are

perrhenate, persulfate, ferricyanide, hexafluorophosphate, and hexachloroplatinate. Examples of organic anions titratable are nitroform, tetraphenylborate, cyanotriphenylborate, picrate, long-chain sulfates and sulfonates, and some soaps. The reverse titration of quaternary ammonium halides vs dodecylsulfate is also feasible. Some titrations are feasible in a partially nonaqueous medium.     

Uranyl-salophen based ditopic receptors for the recognition of quaternary ammonium halides

Uranyl-salophen complexes endowed with aromatic side arms behave as very efficient ditopic receptors towards tetralkylammonium halides as a result of a combination of Lewis acid-base and cation-pi interactions.     

Studies on extraction of thorium from nitrate solutions with quaternary ammonium halides

Thorium can be quantitatively extracted with 0.1 M Hyamine 1622 in dichloroethane from 0.25M nitric acid/2M sodium nitrate and stripped from the organic phase with 0.1M sulphuric acid. The equilibration takes 20 min. Thorium can thus be separated from a large number of elements which are usually associated with it in monazite and in fission products of nuclear fuel.     

Studies on extraction of beryllium from thiocyanate solutions by quaternary ammonium halides

A 0.4M tricaprylmethylammonium chloride solution in n-hexane was used for the quantitative extraction of beryllium from hydrochloric acid (pH 3) and 5M potassium thiocyanate. Beryllium was stripped from the organic phase with 1M sodium hydroxide, then determined volumetrically with bismuthyl perchlorate and bromocresol green indicator. Beryllium was extracted in presence of a large number of elements which are usually associated with it in beryl and in fission products of nuclear fuel.     

Palladium‐catalyzed carbonylation of quaternary ammonium halides to tertiary amides

Catalytic carbonylation of quaternary ammonium salts under anhydrous conditions was investigated using palladium catalyst. The carbonylation of tetramethylammonium iodide was chosen as a model reaction and studied systematically. Ligand‐free PdCl₂ showed efficient catalytic performance for this transformation. A palladium catalyst loading as low as 0.05 mol% was sufficient for high yield (96.9%) of N,N‐dimethylacetamide, corresponding to a turnover frequency of 242 h^?1. Under optimum conditions, several other quaternary ammonium halides were also carbonylated to corresponding tertiary amides in moderate to excellent yields. The catalytic activity of commercial palladium on activated carbon (Pd/C) catalyst was also evaluated. The Pd/C catalyst exhibited high activity for this carbonylation reaction and could be recycled six times with a slight decrease in activity. Furthermore, mechanistic considerations concerning Pd‐catalyzed carbonylation of quaternary ammonium halides were also discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Hydrogen bonding in phosphonate cavitands: Investigation of host-guest complexes with ammonium salts

The H-bonding in alkylammonium complexes of phosphonate cavitands were studied by mass spectrometric methods and theoretical calculations. The alkylammonium ions included primary, secondary, and tertiary methyl- and ethylammonium ions. Their complexation with mono-, tetra-, and two di-phosphonate cavitands, which differ according to the number and position of H-bond acceptor P = O groups, was evaluated by using different competition experiments, energy-resolved CID, gas-phase H/D-exchange, and ligand-exchange reactions, together with ab initio theoretical optimization of the complexes. The phosphonate cavitands with two or more adjacent P = O groups were found to be selective towards secondary alkylammonium ions, due to simultaneous formation of two stable hydrogen bonds. In the ion-molecule reactions (both H/D- and ligand-exchange), the formation of two stable hydrogen bonds was observed either to slow down the reaction or to completely prevent it. This was, however, limited to situations where two hydrogen bonds are formed between the H-bond donor sites of the alkyl ammonium ion and the vicinal H-bond acceptor sites of the cavitand.     

Synthesis and aggregation behavior of a hexameric quaternary ammonium surfactant

A star-shaped hexameric quaternary ammonium surfactant (PAHB), bearing six hydrophobic chains and six charged hydrophilic headgroups connected by an amide-type spacer group, was synthesized. The self-assembly behavior of the surfactant in aqueous solution was studied by surface tension, electrical conductivity, isothermal titration microcalorimetry, dynamic light scattering, cryogenic transmission electron microscopy, and NMR techniques. The results reveal that there are two critical aggregate concentrations during the process of aggregation, namely C(1) and C(2). The aggregate transitions are proved to be caused by the changes of the surfactant configuration through hydrophobic interaction among the hydrocarbon chains. Below C(1), PAHB may present a star-shaped molecular configuration due to intramolecular electrostatic repulsion among the charged headgroups, and large aggregates with network-like structure are observed. Between C(1) and C(2), the hydrophobic interaction among the hydrophobic chains may become stronger to make the hydrophobic chains of the PAHB molecules curve back and pack more closely, and then the network-like aggregates transfer to large spherical aggregates of ～100 nm. Beyond C(2), the hydrophobic interaction may become strong enough to cause the PAHB molecular configuration to turn into a pyramid-like shape, resulting in the transition of the spherical large aggregates to spherical micelles of ～10 nm. Interestingly, the PAHB displays high emulsification ability to linear fatty alkyls even at very low concentration.     

Effects of tertiary amines and quaternary ammonium halides in polysulfone on membrane gas separation properties

Polymers containing CO₂‐philic groups are of great interest for CO₂/light gas separation membranes because the affinity toward CO₂ can effectively increase CO₂ solubility and thus permeability. In this study, polysulfones (PSUs) modified with different degrees of benzyldimethylamine (DMA), benzyltrimethylammonium fluoride (TMAF), and benzyltrimethylammonium iodide (TMAI) were synthesized using sequential post‐functionalization reactions and investigated for CO₂/N₂ and CO₂/CH₄ separation. The physical properties of these polymers were studied, including density, fractional free volume, and glass transition temperature. In contrast to the conventional wisdom that tertiary amines exhibit an affinity toward CO₂, this study convincingly shows that the DMA substituent has a minimal impact on CO₂ solubility and CO₂/light gas solubility selectivity in PSUs under dry condition. On the other hand, incorporating TMAF and TMAI in PSU significantly increases CO₂ solubility. Particularly, introducing TMAI with a molar ratio of 1.07 relative to PSU repeating units increases CO₂/CH₄ solubility from 4.4 to 5.2, CO₂/CH₄ permeability selectivity from 21 to 45, and CO₂/N₂ permeability selectivity from 24 to 33 at 35 °C, while the CO₂ permeability decreases from 5.6 to 1.7 Barrers. The effect of these functional groups in PSUs on gas diffusivity and diffusivity selectivity can be satisfactorily described by the free volume model. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1239–1250     

Hydrogen bonding: Part 18. The nature of the OHF hydrogen bond in choline fluoride

The infrared spectrum of the OHF hydrogen bond in choline fluoride is completely different from the spectra of the electrostatic O—H?X hydrogen bonds in the other choline halides; however, this spectrum cannot be accounted for in terms of a “very strong” covalent OHF bond such as those found in carboxylic acid—fluoride ion complexes or postulated for betaine hydrofluoride. The spectrum of choline fluoride is interpreted best in terms of an intermediate type of unsymmetrical hydrogen bond (r° O?F = ～ 256 pm) which shows strong intensity enhancement for the first overtone of the OHF bending vibration.     

Lipophilic counterion effect on aggregation and adsorption behavior of quaternary ammonium surfactants

The obvious different aggregation and adsorption behavior of six newly quaternary ammonium surfactants with different lipophilic counterions has been discoverd by measurements of equilibrium and dynamic surface tension, fluorescence and conductivity. Interestingly, the critical micelle concentration (CMC) and its surface tension γ_CMC decrease with the increasing counterion chain length. However, three methods have confirmed that an exception of CMC increases slightly from C₁₆NC₁ to C₁₆NC₂. According to experimental results, a balanced mechanism between hydrophobicity and electrostatic of counterion is proposed. Besides, the dynamic surface tension results show the diffusion coefficient increases with the increasing counterion length both at a short time (D_t?→?0) and long time (D_t?→?∞), which indicates a faster adsorption process. Unlike the inorganic counterion, the diffusion coefficient decreases with the increase of hydrophobic chain length. This is attributed to the strong electrostatic interactions between counterions and cationic headgroups.     

Hydrogen bonding : Part 17. IR and NMR study of the lower hydrates of choline chloride

Choline chloride forms two lower hydrates — a dihydrate and a monohydrate — with quite unusual properties. The dihydrate is a highly structured liquid salt; the IR spectrum is similar to that of a crystalline framework clathrate hydrate, and there are separate ¹H-NMR signals for the cation hydroxyl and water protons. The dihydrate is a crystalline solid at reduced pressure. The crystalline monohydrate only exists at reduced pressure; at atmospheric pressure it disproportionates to liquid dihydrate and anhydrous choline chloride. The anhydrous choline chloride thus formed is a previously unreported crystal modification of choline chloride.     

Interfacial dilational viscoelasticity and foam stability in quaternary ammonium gemini surfactant systems: influence of intermolecular hydrogen bonding

This paper reports the adsorption and interfacial viscoelasticity of gemini surfactants with a hydroxyl-substituted spacer, 2-hydroxyl-propanediyl-α,ω-bis(dimethyldodecylammonium bromide), 2-hydroxyl-butanediyl-α,ω-bis(dimethyldodecylammonium bromide), and 2,3-hydroxyl-butanediyl-α,ω-bis(dimethyldodecylammonium bromide), referred to as 12-3(OH)-12, 12-4(OH)-12, and 12-4(OH)₂-12, respectively, at the air/water interface using dropping shape and interface dilational rheology measurements. For comparison, the unsubstituted surfactants were also examined at identical conditions. The results showed that substituted surfactants produced a remarkably higher interfacial elasticity than the corresponding unsubstituted ones. This was attributed to the effect of the intermolecular hydrogen bonding occurring between the hydroxyl-substituted spacers of adsorbed molecules, which resulted in tighter packing of the molecules in the monolayer. Besides, we measured foam stability. The foam produced by the substituted geminis was found to have higher stability than that by the unsubstituted geminis. It was suggested that the foam stability may be related to the limit elasticity of interfacial film at the level of identical surface excesses.