Tetraalkylammonium Chlorides Research Articles

Tetraalkylammonium Chlorides as Melting Point Depressants of Ionic Liquids

Tetraalkylammonium Chlorides as Melting Point Depressants of Ionic Liquids

The role of ionic vs. non-ionic excipients in APIs-based eutectic systems

Aiming to contribute to drug pre-formulation, new eutectic mixtures were developed. Thymol, coumarin, or quaternary ammonium chlorides as excipients, were combined with the active pharmaceutical ingredients (APIs) acetylsalicylic acid, acetaminophen, ibuprofen, ketoprofen, or lidocaine. Their solid-liquid equilibrium (SLE) binary phase diagrams were measured to study eventual phase separation between the compounds, preventing manufacturing problems, and to study the molecular interactions between the APIs and ionic or non-ionic excipients. The Conductor-like Screening Model for Real Solvents (COSMO-RS) capability to predict the SLE of mixtures containing non-ionic excipients was further evaluated. COSMO-RS gives a good quantitative description of the experimental SLE being a tool with great potential in the screening of eutectic systems containing APIs and non-ionic excipients. While thymol presents strong interactions with the APIs, and consequently negative deviations to thermodynamic ideality, systems containing coumarin follow a quasi-ideal behavior. Regarding the ionic excipients, both choline chloride and the tetraalkylammonium chlorides are unable to establish relevant interactions with the APIs, and no significant negative deviations to ideality are observed. The liquefaction of the APIs here studied is favored by using non-ionic excipients, such as thymol, due to the strong interactions it can establish with the APIs.

Molecular sieving of tetraalkylammonium cations on cation exchange systems in DC electric field

Ion exchange membranes and ion exchange resin particles are widely used in electro-membrane separation processes such as electrodeionization and electrodialysis. The internal structure of these ion exchange systems implicitly determines their properties, which, in turn, strongly affect the efficiency of the separation process. Here, we indirectly investigate the internal structure of a heterogeneous cation exchange membrane and cation exchange resin particles with the use of homologous series of tetraalkylammonium chlorides. The tetraalkylammonium cations form a series of cations of various sizes amendable for sieving on the studied systems. This series is used for determination of the cation of critical size. The performed experimental study focuses on investigating characteristic features of current-voltage curves measured for individual tetraalkylammonium chloride solutions and their effect on water splitting reaction and electroconvection. Our experimental data show that while tetramethyl-, tetraethyl-, and tetrapropylammonium cations can easily be exchanged by both the membranes and the resin particles, tetrapentyl- and tetrahexylammonium cations are poorly exchanged by both studied systems due to their size. Tetrabutylammonium cation, possessing the Stokes diameter of around 1 nm, turns out to be the cation with the critical size. We observe a strong effect of the counterion size on the occurrence of electroconvection that is pertinent to the overlimiting region of the ion exchange systems. While small counterions allow intensive electroconvection to develop, large counterions have a damping effect on the electroconvective motion. The measurement of the pH changes in our systems during chronoamperometric experiments indicates that water splitting takes place in none of them. Our results classify counterions into two groups based on their ability to pass through the investigated cation exchange systems. The first group includes counterions easily exchanged by the ion exchange system. The other group contains cations that cannot be exchanged due to their size. The counterions from the second group are possible foulants with increased potential for adsorption onto the cation exchange systems due to strong electrostatic attractions. Our technique can be used for the determination of critical sizes of other cation exchange systems.

Characterization of inclusion complexation of various tetraalkylammonium chlorides with cucurbit[7]uril by external high-pressure studies

The inclusion constants of tetraalkylammonium salts (ASs) with cucurbit[7]uril (CB[7]) were determined at high-pressures using methylene blue as a chemical indicator. CB[7] formed 1:1 inclusion complexes with ASs. We found a characteristic dependence of the alkyl chain substituents in ASs on the inclusion equilibrium, which was responsible for the formation of clathrate hydrates of the AS in bulk. Furthermore, we examined the effects of external high pressures on the CB[7] inclusion complexations of ASs having different alkyl chain lengths. Pressure dependence experiments allowed us to calculate the reaction volume (ΔV) upon inclusion; i.e., the volume change (ΔVdesolv) accompanying desolvation around the guest molecules and the volume change (ΔVrepel) caused by the water molecules repelled from the CB[7] cavity. The volumetric study for the inclusion of ASs with CB[7] showed that in the tetraheptylammonium ion, one arm (alkyl chain) was encapsulated in the CB[7] cavity, while in other ASs, two arms were located in the cavity. NMR measurements of the complexes and pressure-dependent studies provided unique information on the structures of the inclusion complexes of ASs with CB[7].

Electrochemical interpretation of parabolic relation between the hydrophobicity and the permeability of tetraalkylammonium chlorides

Transport of hydrophobic tetraalkylammonium chlorides (tetrabutylammonium, tetrapentylammonium, tetrahexylammonium and tetraheptylammonium) across a porous polytetrafluoroethylene resin film impregnated by 1-octanol between two aqueous phases is interpreted by considering the steady-state flows of both the tetraalkylammonium ion and the chloride ion within both the aqueous and the membrane phases. The parabolic relation between the hydrophobicity and the permeability in the quantitative structure-activity relationship is attributable to whether the transport of both ions within the aqueous phases or that within the membrane phase is the rate-determining step in the cell system.

Heat effects measured in aqueous solutions of salts of poly(anethole sulfonic acid) upon mixing with alkali-, alkaline-earth-, and tetraalkylammonium chlorides

Abstract Experimental and theoretical results for the enthalpies of mixing, Δ mix H , for aqueous solutions of selected salts of polyanethole sulfonic acid with some low-molecular-mass salts are presented. The enthalpies of mixing for aqueous solutions of alkali (Li + , Cs + ) and tetraalkylammonium (Me 4 N + , Bu 4 N + ) polyanethole sulfonates (PAS − ) with alkali-metal chlorides (LiCl, KCl, CsCl) and tetraalkylammonium chlorides (Me 4 NCl, Et 4 NCl, Pr 4 NCl, Bu 4 NCl) were measured with an isothermal titration calorimeter at 298.15 K. The first two polysalts (LiPAS, CsPAS) were also titrated with MgCl 2 and SrCl 2 solutions. Manning's theory was used to predict the electrostatic contribution to the enthalpy of mixing for polyelectrolyte and simple electrolyte solutions. The observed differences between the experimental and calculated values were ascribed to the ion-specific interactions. The cumulative heat effects obtained from the titration of the poly(anethole sulfonic) salts with the alkali chlorides, including Me 4 NCl, for a molar ratio r = 4.6, decreased with the hydration enthalpy, ∆ hyd H , of the added counterions. In contrast to this, the enthalpies of mixing for poly(anethole sulfonic) salts with tetraalkylammonium chlorides increased with the length of the alkyl chain in the added counterion. The results show a strong dependence of the enthalpy of mixing on the difference in the nature of the counterions in the mixture. Additionally, the results allow us to classify the counterions as either hydrophilic or hydrophobic based on the heat effects provoked by their introduction into a polyelectrolyte solution.

Gelation and decrystallization of cellulose by TAAHs/DMSO treatment and the role of anions and cations

Compact crystalline cellulose was structurally transformed into a loose regenerated form using treatment with tetraalkylammonium halides in dimethyl sulfoxide (TAAHs/DMSO) and gel formation using water. Swelling of cellulose was affected by the TAAHs content in DMSO and the anion and/or cation type. The cellulose swelling ratio of TAAHs/DMSO was in the order of F− > Cl− > Br− ≈ I− due to differences between hydrogen bond basicity (β) values of TAAHs/DMSO. The swelling ratio varied with the cation size of tetraalkylammonium chlorides (TAACs). For tetraalkylammonium fluorides (TAAFs), swelling ratios were all high and independent of cation size. Decrystallization of cellulose varied with the TAAHs anion and/or cation type in a pattern similar to cellulose swelling ratios. Structural transformation of cellulose, which is due to disruption of hydrogen bonds and van der Waals and hydrophobic interactions in cellulose chains and sheets by anions and cations of TAAHs, was confirmed based on FT-IR, XRD, FE-SEM, TGA, and enzymatic hydrolysis reactions.

Efficient Cellulose Solvent: Quaternary Ammonium Chlorides

Pure quaternary tetraalkylammonium chlorides with one long alkyl chain dissolved in various organic solvents constitute a new class of cellulose solvents. The electrolytes are prepared in high yields and purity by Menshutkin quaternization, an inexpensive and easy synthesis route. The pure molten tetraalkylammonium chlorides dissolve up to 15 wt% of cellulose. Cosolvents, including N,N-dimethylacetamide (DMA), may be added in large excess, leading to a system of decreased viscosity. Contrary to the well-established solvent DMA/LiCl, cellulose dissolves in DMA/quaternary ammonium chlorides without any pretreatment. Thus, the use of the new solvent avoids some disadvantages of DMA/LiCl and ionic liquids, the most extensively employed solvents for homogeneous cellulose chemistry.

Catalytic performance of montmorillonite clay ion-exchanged with ionic liquids in the cycloaddition of carbon dioxide to allyl glycidyl ether

In this study, various ionic liquids immobilized onto montmorillonite clay (IL-MMT) were prepared by ion-exchange reaction between the ionic liquids and ions in the clay interlayer. Tetra-alkyl ammonium chlorides were used as the ionic liquid precursors. The IL-MMTs were characterized by elemental analyses (EA), BET, XRD, 13C NMR, FT-IR, and SEM. The surface areas and d-spacings of the IL-MMTs increased with increasing alkyl chain lengths. The IL-MMTs showed good catalytic activity for the synthesis of the cyclic carbonate from alkyl glycidyl ether (AGE) and carbon dioxide. The effects of the IL cation structure, and reaction parameters such as temperature and CO2 pressure on the reactivity of IL-MMTs were also discussed. The catalyst could be reused in up to four consecutive runs without a significant reduction in the initial activity.

Synthesis and properties of tetraalkylammonium chlorides peroxosolvates (CH3)4NCI·H2O2 and (C2H5)4NCl·H2O2

Tetraalkylammonium chlorides peroxosolvates (CH3)4NCl·H2O2 and (C2H5)4NCl·H2O2 were synthesized. The composition of the solvates was proved by chemical analysis; their X-ray patterns, IR spectra, and thermograms were obtained. The solubility of the solvates in water and their stability in aqueous solutions were investigated.

Tetraalkylammonium derivatives as real-time PCR enhancers and stabilizers of the qPCR mixtures containing SYBR Green I

Tetraalkylammonium (TAA) derivatives have been reported to serve as stabilizers of asymmetrical cyanine dyes in aqueous solutions and to increase the yield and efficiency of polymerase chain reaction (PCR) detected by end-point analysis. In this study, we compared the ability of various TAA derivatives (with alkyl chain ranging from 1 to 5 carbons) and some other compounds to serve as enhancers of real-time PCR based on fluorescence detection from intercalating dye SYBR Green I (SGI). Our data indicate that TAA chlorides and some other TAA derivatives serve as potent enhancers of SGI-monitored real-time PCR. Optimal results were obtained with 10–16 mM tetrapropylammonium chloride. The effect of TAA compounds was dependent on the nature of counter ions present and composition of the reaction mixtures used. Based on measurements of SGI-generated fluorescence signal in the presence of PCR-amplified DNA fragments, oligonucleotide primers and/or various additives, we propose that TAA-derivatives reduce the binding of SGI to oligonucleotide primers and thus enhance primer–template interactions during annealing phase. Furthermore, these compounds serve as stabilizers of SGI-containing PCR mixtures. The combined data indicate that TAA derivatives might be a new class of additives contributing to robustness of real-time PCR monitored by asymmetrical cyanine dye SGI.

Potentiometric characterisation of a dual-stream electrochemical microfluidic device

A microfluidic device is presented with off-chip electrodes residing in a reservoir and connected via micro-capillaries to the Y-shaped microfluidic channel. The device is tested by potentiometric measurements involving dual-stream laminar flow of two aqueous solutions carrying different electrolytes at various concentrations. Open circuit potentials are measured for a series of solutions of alkali metal chlorides and tetraalkylammonium chlorides as well as for dilute hydrochloric acid. The open circuit potential for the microfluidic chip was calculated by taking into account the diffusion potential at finite ionic strength as well as the potential difference introduced by the reference electrode system. The liquid junction potential developed at the boundary of the co-flowing aqueous solutions may be manipulated to have greater or lesser relative contributions to the measured open circuit potential based on use of electrolyte salts having cation and anion pairs of similar or dissimilar mobilities in solution. A reasonable agreement between theoretical and experimental values of the open circuit potential is observed for these situations. The results show that simple microfluidic structures possess a rich environment for exploration and application of the solution chemistry of ions.

NMR investigation on micellization of ammonium/tetraalkylammonium perfluorooctanoates

Abstract The micellization of ammonium/tetraalkylammonium perfluorooctanoates (C 7 F 15 COON(C n H 2 n +1 ) 4 , n = 0–4) was investigated by 1 H and 19 F NMR. Tetraalkylammonium chlorides were also studied by 1 H NMR to simulate the layer of bound counterions on micellar surface. The critical micelle concentration (cmc) determined by NMR was found to decrease with the size of counterions. It was directly proved from the chemical shift change that the longer the alkyl moieties of counterions, the tighter is the contact between perfluorooctanoate headgroups and counterions. Possible conformations of counterions bound to micellar surface were proposed from the chemical shift analysis. The hydrophobicity and structures of counterions with long alkyl chains such as N(C 3 H 7 ) 4 + and N(C 4 H 9 ) 4 + seemed to result in folded, shrink or penetration conformation, rather than ideal models with symmetrically stretched alkyl chains.

Thermal analysis of some organoclays

Thermogravimetric (TG) and differential thermal analysis (DTA) curves of methyltributylammonium smectite (MTBAS), methyltrioctylammonium smectite (MTOAS), and di(hydrogenatedtallow)dimethylammonium smectite (DHTDMAS), and also corresponding sodium smectite (NaS) and tetraalkylammonium chlorides (TAAC) were determined. The TAACs was decomposed exactly by heating up to 500°C. The adsorbed water content of 8.0% in the pure NaS was decreased down to 0.2% depending on the size of the non-polar alkyl groups in the tetraalkylammonium cations (TAA+). The thermal degradation of the organic partition nanophase formed between 2:1 layers of smectite occurs between 250–500°C. Activation energies (E) of the thermal degradations in the MTBAS, MTOAS and DHTDMAS are 13.4, 21.9, and 43.5 kJ mol−1, respectively. The E value increases by increasing of the interlayer spacing along a curve depending on the size of the alkyl groups in the TAA+.

An Efficient Route to Aliphatic 2,2‐Dichloroaldehydes via Chlorination of Aldehydes or Alcohols with the System Cl2/Quaternary Ammonium Chloride.

AbstractFor Abstract see ChemInform Abstract in Full Text.

An Efficient Route to Aliphatic 2,2-Dichloroaldehydes via Chlorination of Aldehydes or Alcohols with the System Cl2/Quaternary Ammonium Chloride

An effective and low waste method for preparing aliphatic 2,2-dichluroaldehydes has been achieved by halogenation of aldehydes or alcohols with Cl 2 , using tetraalkylammonium chlorides as recoverable catalysts.

Polyacrylates in aqueous solution. The dependence of protonation on molecular weight, ionic medium and ionic strength

The protonation constants of polyacrylates with different molecular weights ( W=2000–750 000 Da) were determined in different ionic media (alkali metal chlorides and nitrates, tetraalkylammonium chlorides), at 25 °C, by potentiometric measurements (H +–glass electrode). Literature data were also considered. Different models used to analyse protonation data were compared: the first was the modified Henderson–Hasselbalch two-parameter equation, and the second was the three-parameter equation proposed by Högfeldt. The dependence on the ionic strength of the different supporting electrolytes and all the protonation parameters involved in the two models showed the trend Et 4N +≫Li +>Na +≥K +, in accordance with the tendencies of these cations to interact with polycarboxylates. The dependence on molecular weight shows a slightly increasing effect with N (number of monomer units in the polyelectrolyte). Empirical relationships were found for the dependence of the protonation parameters on both ionic strength (I/mol l −1) and N. The use of protonation data was considered for polyacrylates in speciation studies, and specific interaction parameters were calculated according to the SIT (Specific Ion Interaction Theory) model.

Ionic Viscosity B-Coefficients of Tetraalkyl Ammonium Chlorides in (0 to 100) Mass Water + Methanol at 298.15 K

The viscosities of tetraalkylammonium chlorides, R4NCl (R = −CH3 through n-C4H9), have been measured in (0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100) mass % aqueous methanol at 298.15 K. By using the Jones−Dole equation, the corresponding B-coefficients have been calculated. The ionic B-values have been determined using the “reference electrolyte” KCI. Solvation number (ns) values have been used to discuss the solvation of ions.

Novel Class of Ionic Metallomesogens without Organic Ligands: Thermotropic Liquid-Crystalline Behavior of Tetrachlorometalate Salts and Distinct Polymorphic Transition in Smectic A Phases

The thermotropic liquid-crystalline behavior of the metal complex salts [(C18H37)(CH3)3N]2[MCl4] and [(C18H37)2(CH3)2N]2[MCl4] (M = Co, Ni, Cu, Zn, Cd) was evaluated by differential scanning calorimetry, polarizing optical microscopy, X-ray diffractometry, and electronic absorption as well as by Raman spectroscopy. Introduction of divalent metal ions into the cationic amphiphiles was found to result in enhancement of their thermal properties. Although the parent tetraalkylammonium chlorides showed no liquid-crystalline phase (or indistinct transition behavior), the derived tetrachlorometalate salts exhibited a stable liquid-crystalline phase and simple phase transition behavior. For instance, the tetrachlorocobaltate salt, [(C18H37)2(CH3)2N]2[CoCl4], showed a smectic A (SA) phase in an extremely wide temperature range from 45 to 155 °C on heating. In the SA phase, the complexes were confirmed to form a layered self-assembly that is built up from alternating layers of tetrahedral [MCl4]2- ions and flexible alkyl segments. Furthermore, distinct polymorphism in the SA phase was observed for several tetrachlorometalate salts, which differs essentially from the SA−SA transition described in the usual rodlike liquid crystals.

Intramolecularly selective decomposition of surfactant molecules on photocatalytic oxidative degradation over TiO 2 photocatalyst

Investigation on oxidative mineralization of various surfactants over TiO 2 photocatalyst reveals an anomalously retarded degradation of the trimethylammonium moiety in cationic surfactants. Model reactions using tetraalkylammonium chlorides as substrates confirm that the stepwise behavior of the mineralization time courses is ascribed to intramolecularly selective decomposition caused by a considerably slow degradation rate of the methyl groups directly bound to the quaternary nitrogen. A strong inhibition effect of bromide or iodide anions preventing the complete mineralization is also revealed.