Use Of Quaternary Ammonium Salts Research Articles

Variations in growth, photosynthesis, oxidative stress and microcystin production in Microcystis aeruginosa caused by acute exposure to Benzalkonium Chloride and Benzalkonium Bromide

Due to the COVID-19 pandemic, the use of quaternary ammonium salts (QACs) and their release into the aquatic environment increased dramatically. The ecological risks of QACs still need to be explored. Two extensively used QACs, Benzalkonium Chloride (BAC) and Benzalkonium Bromine (BAB), were selected to explore their acute toxic effects on a common bloom-forming cyanobacterium M. aeruginosa. Both QACs had the same 96 h-EC50 concentration on M. aeruginosa, which was 0.97 mg L-1. Nevertheless, BAC was able to inhibit the growth of M. aeruginosa at real environmental concentrations. Under the EC50 concentration, the inhibition of photosynthesis was more intense induced by BAC than BAB. The ROS levels under BAC and BAB stress were 5.88 and 4.31 times of the control, demonstrating that the oxidative stress caused by BAC was stronger. Notably, the increase of antioxidant substances such as SOD, CAT and GSH and the significant upregulation of genes such as sod2 proved that oxidation defense mechanisms were activated in response to the stressors. Both QACs significantly promoted the synthesis and release of microcystin-LR but the mechanism was different. The effects of QACs on microbial and algal communities and on microcystins synthesis should be paid special attention in future environmental management work.

A Radical Pathway and Stabilized Li Anode Enabled by Halide Quaternary Ammonium Electrolyte Additives for Lithium‐Sulfur Batteries

AbstractPassivation of the sulfur cathode by insulating lithium sulfide restricts the reversibility and sulfur utilization of Li−S batteries. 3D nucleation of Li2S enabled by radical conversion may significantly boost the redox kinetics. Electrolytes with high donor number (DN) solvents allow for tri‐sulfur (S3⋅−) radicals as intermediates, however, the catastrophic reactivity of such solvents with Li anodes pose a great challenge for their practical application. Here, we propose the use of quaternary ammonium salts as electrolyte additives, which can preserve the partial high‐DN characteristics that trigger the S3⋅− radical pathway, and inhibit the growth of Li dendrites. Li−S batteries with tetrapropylammonium bromide (T3Br) electrolyte additive deliver the outstanding cycling stability (700 cycles at 1 C with a low‐capacity decay rate of 0.049 % per cycle), and high capacity under a lean electrolyte of 5 μLelectrolyte mgsulfur−1. This work opens a new avenue for the development of electrolyte additives for Li−S batteries.

A Radical Pathway and Stabilized Li Anode Enabled by Halide Quaternary Ammonium Electrolyte Additives for Lithium-Sulfur Batteries.

Passivation of the sulfur cathode by insulating lithium sulfide restricts the reversibility and sulfur utilization of Li-S batteries. 3D nucleation of Li2 S enabled by radical conversion may significantly boost the redox kinetics. Electrolytes with high donor number (DN) solvents allow for tri-sulfur (S3 ⋅- ) radicals as intermediates, however, the catastrophic reactivity of such solvents with Li anodes pose a great challenge for their practical application. Here, we propose the use of quaternary ammonium salts as electrolyte additives, which can preserve the partial high-DN characteristics that trigger the S3 ⋅- radical pathway, and inhibit the growth of Li dendrites. Li-S batteries with tetrapropylammonium bromide (T3Br) electrolyte additive deliver the outstanding cycling stability (700 cycles at 1 C with a low-capacity decay rate of 0.049 % per cycle), and high capacity under a lean electrolyte of 5 μLelectrolyte mgsulfur -1 . This work opens a new avenue for the development of electrolyte additives for Li-S batteries.

Use of quaternary ammonium salt as a dye fixing agent and antimicrobial agent in sustainable, single-step single-bath dyeing and finishing

In this investigation, a novel sustainable approach was employed to combine the dyeing and antimicrobial finishing steps for nylon fabric in a decamethylcyclopentasiloxane (D5) non-aqueous media dyeing system. Nylon fabric was dyed with acid dye and quaternary ammonium salt (QAS). Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride was employed in the dyebath as a fixing agent. The dyeing efficiency was assessed by measuring the color characteristics and colorfastness of the dyed fabric. The success of antibacterial treatment was analyzed by observing the reduction in bacteria colony forming units. These results showed that uniformly dyed samples with higher color strength than the aqueous bath and excellent colorfastness were obtained in the D5 non-aqueous media dyeing system. After five Launder-Ometer washing cycles, the treated samples still showed good antibacterial activity. These results showed that the acid dyeing and QAS finishing processes of nylon fabric can be carried out in a D5 solvent bath at the same time.

Quaternary Ammonium Salts Anchored on Cross-Linked (R)-(+)-Lipoic Acid Nanoparticles for Drug-Resistant Tumor Therapy.

A membrane-lytic mechanism-based nanodrug is developed for drug-resistant tumor therapy by anchoring the small-molecule quaternary ammonium salt (QAS) on cross-linked (R)-(+)-lipoic acid nanoparticles (cLANs). The anchoring of QAS on the nanoparticle avoids the direct attack of long alkyl chains to the cell membrane under physiological conditions, while after entering tumor cells, the QAS is released from the dissociated cLANs, migrates to the phospholipid bilayer via electrostatic interaction, and destroys the cell membrane by the puncture of long alkyl chains. Since the QAS is designed to finally be hydrolyzed to amino acid betaine and food additive cetanol and the cLANs degrade to dihydrolipoic acid (DHLA, reduced form of dietary antioxidant lipoic acid in cells), the QAS@cLANs hold superior biosafety. In addition to the drug-resistant tumors, the QAS@cLANs demonstrate significant inhibition of metastatic tumors. This work provides not only a general and clinic-promising treatment for the refractory tumors but also opens a door for the medicinal use of QAS.

Influence of the Polymer Architecture and Functionalization with Carboxylate Groups over the Release of Octenidine Hydrochloride from Poly(lactic acid)‐Based Nanoparticles

AbstractHealthcare‐associated infections affect every year more than four million people due to the increasing resistance of bacteria to traditional antibiotics. In turn, the systematic use of quaternary ammonium salts as antiseptics is hampered by their inherent toxicity and high hydrophilicity that leads to their rapid elimination from the body. Therefore, a carefully controlled release of these antiseptics is pivotal to achieve prolonged therapeutic efficacy reducing the side effects. In this work, high encapsulation efficiencies and good control over the release of octenidine hydrochloride from poly(lactic acid) (PLA)‐based nanoparticles (NPs) is achieved by introducing functional carboxylate groups in the polymer. The influence of the polymer structure and functionalization over the drug release is systematically investigated. Star‐like and brush‐like polymers with tunable number of ionizable chain end‐groups are synthesized via combination of ring‐opening polymerization and reversible addition−fragmentation chain transfer polymerization. These polymers are formulated in NPs and loaded with octenidine through emulsion/solvent evaporation. Brush‐like polymers demonstrate to be a versatile tool for the modulation of the initial burst and long term release of the antiseptic through the tuning of the electrostatic interactions between the negative groups on the polymer, whose number can be precisely controlled, and the positively charged drug.

Influence of cationic surfactants on physical and mechanical properties of polymer compositions

When creating filled polymer composite materials, difficulties often arise due to poor compatibility of polymers with modifying additives. To solve such problems, surface-active substances (SAS) are successfully used in many industries, but they are practically not used in polymer processing. This is largely due to the insufficient assortment of surfactants produced that are suitable for introduction into polymers, especially film-forming ones. Anionic and nonionic surfactants are used in the synthesis and processing of elastomers, but they are not used in the production of film materials. As for the use of cationic surfactants, there are still no data at all. They differ from other types of surfactants in a variety of structures, in the number and relative positions of cationic centers and hydrophobic radicals, and also in antimicrobial properties. The prospects of using quaternary ammonium salts for the modification of packaging materials are shown. The expediency of using cationic surfactants for the modification of polymeric materials is proved. It is shown that the use of quaternary ammonium salts improves the physical and mechanical properties of films based on polyethylene and polypropylene. It is proved that cationic surfactants are technologically compatible with polyolefins, which allows the processing of polymer compositions by extrusion. Today, the most common polymers for food packaging are polyethylene and polypropylene. This is due to their low cost, safety in contact with food products, and suitability for processing into films of different thicknesses. More and more attention is being paid to the creation of packaging materials with antimicrobial properties. The imparting of such properties is achieved by introducing an antimicrobial additive into the polymer melt. It is most expedient to introduce additives directly into the melt of the polymer composition during processing, since, for example, during the extrusion process, polymer homogenization with the additive.

Transition metal-free carboxylation of terminal alkynes with carbon dioxide through dual activation: Synthesis of propiolic acids

The combination use of quaternary ammonium salt and inorganic base in low-boiling-point solvent is presented as a new strategy for terminal alkyne carboxylation with CO2. The carboxylation of terminal alkyne with CO2 proceeded smoothly in the presence of tetra-n-butylammonium acetate and K2CO3 through dual activation under relatively mild conditions to produce the corresponding propiolic acids in satisfactory to excellent yields.

Copper‐Mediated Cyanation of Aryl C—H Bond with Removable Bidenate Auxiliary Using Acetonitrile as the Cyano Source

AbstractCopper‐mediated cyanation of aryl C—H bond with removable bidenate auxiliary as a directing group has been developed, in which green and cheap acetonitrile is used as the “CN” source. By switching the reaction conditions, the C—H cyanated products and N‐Ar‐phthalimides can be provided in acceptable yields with high chemoselectivity, respectively. The use of quaternary ammonium salt is essential for cyanation reaction.

Phase Transfer Catalysis Improved Synthesis of 3,4-Dihydropyrimidinones

Various 3,4-dihydropyrimidinones can be prepared via Biginelli reaction in aqueous media by using quaternary ammonium salts of different alkyl groups (C4 and C8) and anions (Cl- and Br-) as catalysts. The use of quaternary ammonium salts along with longer alkyl chains increases the yield of the Biginelli reaction; however, bromide ammonium salts are less active than the chloride ones.

Characterization of Brazilian Bentonite Organoclays as sorbents of petroleum-derived fuels

This work focused on preparing and characterizing Brazilian bentonite clay through the use of quaternary ammonium salt so as to apply it as a sorbent for petroleum-derived fuels. Bentonite clay was organophilizated by the intercalation of quaternary ammonium salts such as cetyl-pyridinium chloride and benzalkonium chloride. The resulting materials were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, N2 physisorption and infrared spectroscopy techniques. The clay similarity with petroleum-derived fuels, gasoline and diesel oil were defined by sorption and swelling tests. The increase in basal spacing and the appearance of absorption bands related to the CH2 and CH3 groups confirm the efficiency of Brazilian organoclays. Removal percentages between 50 and 60 for benzene, toluene and xylene indicate the potential of organoclay in the remediation of areas contaminated by petroleum-derived fuels.

Use of quaternary ammonium salts to remove copper–cyanide complexes by solvent extraction

Cyanidation is one of the most common methods for the extraction of precious metals. In this process, effluents frequently contain relatively high concentrations of copper, which may react with cyanide to form cuprocyanide complexes adversely affecting the process. In this preliminary work, the use of solvent extraction to remove the copper–cyanide species from a synthetic solution similar to that of gold mill effluents was studied in order to permit the recycling of the solution into the process. For the extraction of these anions, the quaternary ammonium salts Quartamin TPR, Adogen 464 and Aliquat 336 were studied as extractants. The experimental results showed that for a synthetic solution of 710 mg/L copper and 1100 mg/L cyanide, it is possible to obtain a copper extraction of 99% when using 0.033 mol/L of the extractant Adogen 464 (organic/aqueous volume ratio (O/A) = 1) in the range of pH of 9–11. Up to 99% of the copper can be stripped from the organic solution after three contact times (5 min each) with 50 mL of sodium hydroxide 0.5 M (O/A = 1).

Synthesis and Elaboration of the Dinuclear Iron-Imide Cluster Core [Fe2(μ-NR)2]2+

The protolysis of mononuclear ferric amide precursors FeCl[N(SiMe3)2]2(THF) (1) or [FeCl2{N(SiMe3)2}2]- (2) by primary amines provides, under suitable conditions, an effective route to dinuclear weak-field ferric-imide clusters with [Fe2(mu-NR)2]2+ cores. In the synthesis of known arylimide clusters [Fe2(mu-NAr)2Cl4]2- (Ar = Ph, p-Tol, Mes) from 2, the counterion has a major effect on selectivity and yield, and the use of quaternary ammonium salts affords a substantial improvement over earlier, Li+-based chemistry. The new tert-butylimide core is obtained by protolysis of 1 with excess tBuNH2 to give crystalline cis-Fe2(mu-NtBu)2Cl2(NH2tBu)2 (9). Complex 9 can be transformed to other dinuclear species through substitution of the terminal amines by pyridines, PEt3, or chloride, or through protolysis of bridging alkylimides by arylamines, allowing isolation of trans-Fe2(mu-NtBu)2Cl2(DMAP)2 (DMAP = 4-dimethylaminopyridine), cis-Fe2(mu-NtBu)2Cl2(PEt3)2, [Fe2(mu-NtBu)2Cl4]-, and trans-Fe2(mu-NPh)2Cl2(NH2tBu)2. The susceptibility of alkyl substituents to beta-elimination appears to limit the general applicability of protolytic cluster assembly using alkylamines. The dinuclear clusters have been characterized by X-ray, spectroscopic, and electrochemical analyses.

Role of quaternary ammonium salts in improving the fastness properties of anionic dyes on cellulose fibres

The object of this study was to review the developments taking place during 1990–2005 regarding the use of quaternary ammonium salts as dye fixing agents for improving the fastness properties of anionic dyes on cellulose fibres. As far as fastness properties are concerned, this review is restricted only to fastness to light, washing and water treatments.

Efficient Conversion of Oximes to the Corresponding Carbonyl Compounds with Tetrabutylammonium Chromate under Aprotic Conditions

Oximes are extensively used as preferred and readily prepared derivatives for purification and characterization of carbonyl compounds. Furthermore they play an important role as protecting and selectively a-activating groups in synthetic organic chemistry. Regeneration of ketones and aldehydes from their oximes has assumed added importance since the discovery of the Barton reaction in which oximes are produced at non-activated hydrocarbon sites. Also, their synthesis from non-carbonyl compounds, such as by nitrosation of an active methylene group, nitrosation of an α-halo carbonyl compound and condensation of a nitroalkene with an aldehyde provides a valid alternative pathway to carbonyl compounds. Therefore, there has been a continued interest in the effective regeneration of carbonyl compounds from the corresponding oximes especially under mild conditions. Oxidative and reductive methods have been found to show advantages over the classical hydrolytic methods. Although many oxidizing agents have been used, only a limited number of methods are efficient because of the low solubility of these metallic reagents in most organic solvents. A number of oxidative deoximation methods have been developed which involve chromium (VI) species, but most of them suffers from low yields or long reaction times. Some quaternary ammonium salts such as triethylammonium chlorochromate, prolinium chlorochromate/silica gel and bis(tetrabutylammonium) dichromate under microwave irradiation have shown good yields in deoximation reactions. However, cleavage of aldoximes into carbonyl compounds requires milder reagents to avoid further oxidation. For example, benzaldehyde was obtained from the reaction of corresponding oxime with triethylammonium chlorochromate in only 56% yield. Many easily prepared or commercially available crystalline quaternary ammonium salts of different oxidizing anions have been studied and found some applications in functional group interconversions. For some reasons, it is attractive to use quaternary ammonium salts as reagents for organic transformations. The solubility of these salts in several solvents, selectivity, and absence of side reactions provides advantages of using them in organic synthesis. Tetrabutylammonium chromate (TBAC) is one of these compounds that has been used as a very mild oxidizing agent for conversion of unsaturated alcohols including allylic and benzylic alcohols to the corresponding aldehydes with the double bonds intact. In continuation of our ongoing research program on the use of quaternary ammonium salts as reagents for the approach to novel synthetic methods, we now report efficient conversion of oximes into the corresponding carbonyl compounds by using tetrabutylammonium chromate under homogeneous, aprotic and moderately acidic conditions. We found that the oxidative deprotection of oximes can be easily performed with tetrabutylammonium chromate by refluxing the reaction mixture in acetonitrile

Photo-Induced Thermal Crosslinking of Epoxy Compounds by the Use of Quaternary Ammonium Salts Having Phenacyl Groups.

Photo-Induced Thermal Crosslinking of Epoxy Compounds by the Use of Quaternary Ammonium Salts Having Phenacyl Groups.

Hexamethyltetralin Preparations Effect of Methyltrioctylammonium Chloride on Solvent/Olefin Interdependency

Abstract The use of quaternary ammonium salts as co-catalysts in the AlCl3 catalyzed cyclialkylation of p-cymene, 2-chloro-2methylpropane, and 3,3-dimethylbutene-1 is reported. The addition of co-catalyst, in solvents which normally give low yields of 1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene with 3,3-dimethylbutene-1, improves product yields, comparable with the best published 3,3-dimethylbutene-1 methodology. Addition of co-catalyst permits the use of more environmentally acceptable solvent systems than those in existing syntheses of the desired tetralin. The yield improvement is rationalized on the basis of improved reaction homogeneity, facile cleavage of Al2Cl6 by Cl− ion, and increased effective solvent polarity, promoted by addition of the quaternary ammonium salt co-catalysts. Addition of quat co-catalysts to 3,3-dimethylbutene-1 based cyclialkylation systems did not increase rate, catalyst homogeneity or yield relative to a control (dichloromethane solvent). This suggests that the chlorinated hydrocarbon solvents normally used in this technology provide functions similar to that of quats in 2,3-dimethylbutene-1 based technology. These functions include the abilities to enhance AlCl3 solubility, increase the polarity of the reaction medium, and provide facile scission of Al2Cl6 to a more active catalytic species. In reactions where 2,3-dimethylbutene-1 is substituted for 3,3-dimethylbutene-1, addition of co-catalyst improves reaction rate, catalyst homogeneity, and yield reproducibility in non-polar solvents when compared to the best published, 2,3-dimethylbutene-1 methodology.

Phase Transfer Catalysis without Solvent. Use of Alkyl Iodides

Abstract The Phase Transfer Catalysis (PTC) without solvent method allows the use of quaternary ammonium salts (QAS) when alkyl iodides are used.

Reactive extraction and reextraction of penicillin with different carriers

The extraction and reextraction of Penicillin G was investigated with different reactive components. The degrees E R of reextraction and E G extraction + reextraction were evaluated as a function of the pH value, carrier and penicillin concentrations. Besides Amberlite LA-2, nine different reactive components were tested and diisotridecylamine was found to be the most suitable one. The quaternary ammonium salt Adogen 464 is suitable also for the extraction of penicillin. However, the reextraction is incomplete. Therefore, sodium salt of p-toluene sulfonic acid was used as counter-ion, and it was regenerated by NaOH or Cl − anion. The advantages of the use of quaternary ammonium salts are discussed.

Extraction of steroid sulphates from plasma by use of quaternary ammonium salts

Steroid sulphates are extracted from plasma in good yield by benzene/benzyltributylammonium chloride. Steroid glucuronides are not extracted. This method offers some advantages as compared with the direct solvolysis which is only to be recommended for the determination of steroid sulphates such as dehydroepiandrosterone sulphate which are present in plasma in higher concentrations. The coagulation of plasma proteins with ethanol has the disadvantage that steroid sulphates are adsorbed to the protein precipitated. Furthermore, there is no separation of steroid glucuronides. 17-Hydroxyprogesterone sulphate has not been determined until now in plasma.