Synthesis of cyclic carbonates from epoxides or olefins and CO_2 catalyzed by metal-organic frameworks and quaternary ammonium salts

Catalytic properties of the metal-organic framework Cr-MIL-101 in solvent-free cycloaddition of CO2 to epoxides to produce cyclic carbon- ates using tetrabutylammonium bromide as co-catalyst have been explored under mild reaction conditions （8 bar CO2, 25 ~C）. Styrene and propylene carbonates were formed with high yields （95% and 82%, respectively）. Catalytic performance of Cr-MIL-101 was compared with other MOFs： Fe-MIL-101, Zn-MOF-5 and HKUST-1, The catalytic properties of different quaternary ammonium bromides, Cr-MIL-101 as well as PW12/Cr-MIL-101 composite material have been assessed in oxidative carboxylation of styrene in the presence of both tert-butyl hydroperoxide and H202 as oxidants at 8-100bar CO2 and 25-80 ~C with selectivity to styrene carbonate up to 44% at 57% substrate conversion.

Effect of quaternary ammonium salts on flotation behavior of aluminosilicate minerals

The electrokinetic properties and flotation of diaspore, kaolinite, pyrophyllite and illite with quaternary ammonium salts collectors were studied. The results of flotation tests show that the collecting ability of quaternary ammonium salts for the four minerals is in the order（from strong to weak） ofoctadecyl dimethyl benzyl ammonium chloride（ODBA）, cetyl trimethyl ammonium bromide（CTAB）, dodecyl trimethyl ammonium chloride（DTAC）. Under the condition of alkalescence, it is possible to separate the diaspore from the silicate minerals such as kaolinite, illite and pyrophyllite using quaternary ammonium salts as collector. Isoelectric points （IEP） of diaspore, kaolinite, pyrophyllite and illite are pH=6.0, 3.4, 2.3 and 3.2, respectively. Quaternary ammonium salts can change ζ-potential of the aluminosilicate minerals obviously. The flotation mechanisms were explained by ζ-potential and Fourier transform infrared spectrum （FT-IR） measurements. The results demonstrate that only electrostatic interaction takes place between aluminosilicate minerals （diaspore, kaolinite, pyrophyllite and illite） and quaternary ammonium salts.

Transformation of carbon dioxide into valuable chemicals over bifunctional metallosalen catalysts bearing quaternary phosphonium salts

The chemical transformation of CO2under mild conditions remains a great challenge because of itsexceptional kinetic and thermodynamic stability.Two important reactions in the transformation ofCO2are the N‐formylation reaction of amines using hydrosilanes and CO2,and the cycloaddition ofCO2to epoxides.Here,we report the high efficiency of bifunctional metallosalen complexes bearingquaternary phosphonium salts in catalyzing both of these reactions under solvent‐free,mild conditionswithout the need for co‐catalysts.The catalysts’bifunctionality is attributed to an intramolecularcooperative process between the metal center and the halogen anion.Depending on the reaction,this activates CO2by permitting either the synergistic activation of Si–H bond via metal–hydrogen coordinative bond(M–H)or the dual activation of epoxide via metal–oxygen coordinativebond(M–O).The one‐component catalysts are also shown to be easily recovered and reusedfive times without significant loss of activity or selectivity.The current results are combined withprevious work in the area to propose the relevant reaction mechanisms.

Flotation and adsorption of quaternary ammonium salts collectors on kaolinite of different particle size

The flotation behaviors of decyltrimethylammonium (103C), dodecyltrimethylammonium chloride (DTAC), tetradecyltrimethylammonium chloride (TTAC) and cetyltrimethylammonium chloride (CTAC) on kaolinite of different particle size fraction were studied. The adsorbed amount and adsorption isotherms of collectors on kaolinite were determined for painstaking investigation into the adsorption of quaternary amines at kaolinite-water interface by ultraviolet spectrophotometer methods. The flotation results show that the flotation recovery of kaolinite of different particle fraction increases with an increase in pH when 103C, DTAC, TTAC and CTAC are used as collectors. As the concentration of collectors increases, the flotation recovery increases. Particle size of kaolinite has a strong effect on flotation. The flotation recovery of fine kaolinite decreases with the carbon chain of quaternary ammonium salts collectors increasing, while coarse kaolinite is on the contrary. The adsorbed amount tests and adsorption isotherms show that adsorbed amount increases when the particle size of kaolinite increases or when the carbon chain length of quaternary ammonium salts increases. Within the range of flotation collector concentration, the longer the hydrocarbon chain, the more probable to be absolutely adsorbed by fine kaolinite particles and then the lower the collector concentration in the bulk, which leds to lower flotation recovery.

Synthesis of Chitosan Quaternary Ammonium Salts

A series of N-alkyl or N-aryl chitosan quaternary ammonium salts were prepared via Schiffs base intermediates. Quaternization of N-substituted chitosan derivatives was carried out using methyl iodide to produce water-soluble cationic chitosan quaternary ammonium salt. The products were characterized by IR, (HNMR)-H-1 and elemental analysis. The degree of substitution of chitosan quaternary ammonium salt was calculated by elemental analysis.

Synthesis and Antibacterial Performance of Quaternary Phosphonium Salts with Reactive Hydroxyl Group

Quaternary phosphonium salts （QPS） with reactive groups used as antibacterial agents are promising which could be covalently linked to inert polymer surfaces by in situ polymerization. In this work, two kinds of quaternary phosphonium salts with hydroxyl groups were synthesized successfully. Characterization of these two quaternary phosphonium salts was performed by the Fourier transform infrared spectroscopy （FT-IR） and nuclear magnetic resonance （NMR） spectrometry. The thermal stability and antibacterial activity of antibacterial agents were also investigated by using thermo-gravimetric analysis, differential scanning calorimetry （TG-DSC） and agar diffusion method. The test results showed that these two QPS exhibited good thermal stability and excellent antibacterial activity against both bacteria： Staphylococcus aureus and Escherichia coll.

Studies on a Cationically Modified Quaternary Ammonium Salt of Lignin

A new quaternary ammonium salt monomer was synthesized and a quaternary amination of lignin（ noted as QL）, with the monomer was carried out by grafting copolymerization. The products were characterized by Fourier Transform Infrared spectroscopy（ FTIR）. The experimental results indicate that the yield of the monomer was 99.06%, and the conversion of the monomer and the grafting yield of QL were 93.69% and 185.78%, respectively. The feasibility of QL as the flocculant to be applied in color removal of five artificial dyes, erioehrome black T（dye A）, gongo red（dye B ）, direct fast black G （dye C ）, cuprofix blue green B （dye D ）, and acid black ATT （dye E ） was examined. Results show that OL exhihits the favorable flocculation nerformance and high stability.

Superoxide Anion Radical Scavenging Ability of Quaternary Ammonium Salt of Chitosan

A series of N-alkyl or N-aryl chitosan quaternary ammonium salt were prepared using 96% deacetylated chitosan. Their scavenging activities against superoxide anion radical were investigated by chemiluminescence. The IC50 values of these compounds range from 280 to 880 μg/mL, which should be attributed to their different substitutes.

PREPARATION AND PHOTOSENSITIVITY OF WATER SOLUBLE PHENOLIC RESINS CONTAINING ACRYLOYL AND QUATERNARY AMMONIUM CHLORIDE GROUPS

New water soluble and photocrosslinkable prepolymers containing acrylate and quaternary ammonium salt groups were synthesized from epoxy phenolic resin via ring-opening reaction with acrylic acid and with aqueous solution of triethylamine hydrochloride successively. The second reaction needs no phase transfer catalyst to accelerate, since the product formed can act as a phase transfer catalyst. The prepolymer obtained contains both photocrosslinkable acrylate groups and hydrophilic quaternary ammonium salt groups. Optimum conditions for these reactions were studied. The photosensitivity of the prepolymer was also investigated. The effects of different photoinitiators, different crosslinkable diluent monomers and amine accelerator on the photosensitivity of the prepolymer were compared. The photoinitiator of hydrogen abstraction type is still effective without using amine or alcohol as accelerator, because the prepolymer contains a H beside the OH groups formed in the ring-opening reactions.

Dimethyl carbonate synthesis via transesterification catalyzed by quaternary ammonium salt functionalized chitosan

A quaternary ammonium salt covalently linked to chitosan was first used as a catalyst for dimethyl carbonate （DMC） synthesis by the transesterification of propylene carbonate （PC） with methanol. The effects of various reaction variables like reaction time, temperature and pressure on the catalytic performance were also investigated. 54% DMC yield and 71% PC conversion were obtained under the optimal reaction conditions. Notably, the catalyst was able to be reused with retention of high catalytic activity and selectivity. Consequently, the process presented here has great potential for industrial application due to its advantages such as stability, easy preparation from renewable biopolymer, and simple separation from products.

Preparation of spiro-type quaternary ammonium salt via economical and efficient synthetic route as electrolyte for electric double-layer capacitor

A spiro-type quaternary ammonium salt, spiro-(1,1′)-bipyrrolidinium tetrafluoroborate(SBP-BF4) was successfully prepared by an economical and efficient three-step process comprising the cyclization reaction of 1,4-dibromobutane and pyrrolidine, and subsequent ion exchange pathway with KOH followed by neutralization reaction via HBF4 in the system of ethanol solution. 1H NMR, 13 C NMR, FI-IR and XPS analyses showed the structure of SBP-BF4. The as-obtained SBP-BF4 was dissolved in AN and used as the electrolyte for supercapacitor. Electrochemical measurements demonstrate that, compared with commercial electrolyte TEMA-BF4/AN, SBP-BF4/AN exhibits high ionic conductivity, lower resistance and improved cycling performance, which is due to its smaller ion size and stable symmetry structure.

POLYMER-SUPPORTED SINGLE AND MIXED AMMONIUM AND PHOSPHONIUM SALTS AS CATALYSTS FOR PHASE-TRANSFER REACTIONS

In this study was to investigate, by phase-transfer catalysis, the activity of single and mixed ammonium and phosphonium salts grafted on a 揼el-type?styrene-7% divinylbenzene copolymer in the oxidation of benzyl alcohol with hydrogen peroxide. A wide variety of catalysts with different quaternary groups and different quaternary chain length substituents were examined. The activity of single 搊nium?salts increases as a consequence of the association of ammonium and phosphonium salts grafted on the same polymeric support. The activity of polymer-supported ammonium and phosphonium salts increases with the number of carbon atoms contained in the alkyl radicals of the onium and of the functionalization degree with phosphonium groups.

ANTIBACTERIAL ACTIVITY OF SINGLE AND MIXED AMMONIUM AND PHOSPHONIUM SALTS GRAFTED ON "GEL-TYPE" STYRENE-DIVINYLBENZENE COPOLYMERS

A systematic study on the synthesis and antibacterial activity of the quaternary "onium" salts grafted on an insoluble "gel-type" styrene-7% divinylbenzene copolymer by polymer-analogous reactions is showed. Antibacterial activity of quaternary ammonium and/or phosphonium salts grafted on polymer-supports has been studied against Staphylococcus aureus and Escherichia coli. A wide variety of "onium" salts bound to macromolecular supports with different quaternary groups and different quaternary chain length substituents were examined. The antibacterial activity of mixed "onium" salts increases as a consequence of the association of ammonium and phosphonium salts grafted on the same polymeric support.

Facile fabrication of superior antibacterial cotton fabric based on ZnO nanoparticles/quaternary ammonium salts hybrid composites and mechanism study

In the research for the safe and efficiently antibacterial cotton fabrics to minimize risk for human health,an organic–inorganic hybrid material of ZnO nanoparticles(NPs)and quaternary ammonium salt(QAS)was employed to modify cotton fabrics by a dipping–padding–drying method.The synergistic effects of ZnO NPs and QAS on the structure and antibacterial properties of cotton fabrics were studied in detail.Results displayed that the QAS and ZnO NPs were immobilized firmly in cotton fabric by the formation of chemical covalent bonds and silica gel structure.ZnO/QAS/cotton had a good inhibitory effect on the growth of E.coli and S.aureus,with superior antibacterial efficiency of>99.99%.ZnO/QAS/cotton preserved good mechanical property,water absorbability,and limpness.We also provided a detailed analysis of antibacterial mechanism for the hybrid materials.The contact mechanism and the Zn2+release were considered as the main mechanisms for the ZnO/QAS/cotton,while the reactive oxygen species(ROS)generation only had a little contribution to the antibacterial activity.In short,the excellent integrated properties endowed the hybrid cotton fabrics as potential application in many fields,like healthcare,food packaging.

Antibacterial performance of cationic quaternary phosphonium-modified chitosan polymer in water

Microbial contamination in water has emerged as a critical concern and thus developing biocide materials for controlling microbial contamination is crucial.Removing all pathogenic bacteria in water is difficult when using traditional water treatment technologies.Moreover,these bacteria can easily reproduce during pipeline distribution.In this work,a facile and effective chitosan derivative biocide denoted as PCC was developed by grafting with quaternary phosphonium salt(QPS).PCC became positively charged with a wide range of p H and demonstrated antibacterial activity up to 95%and 100%against Escherichia coli and Staphylococcus aureus as model pathogens,respectively.The grafting of QPS may disrupt the cell membrane and lead to bacterial inactivation,as demonstrated by the scanning electron microscopy image and the concentration of intracellular substance leakage.MTT assay results indicate that PCC achieved good biocompatibility with negligible in vitro cytotoxicity.These findings introduce a promising approach for bacterial decontamination due to its low cytotoxicity and high biocidal activity.

Asymmetric Nucleophilic Additions Promoted by Quaternary Phosphonium Ion-Pair Catalysts

Chiral quaternary phosphonium ion-pair catalysis showcases a distinctive catalytic and stereoinductive mode arising from the synergy between ionic and noncovalent interactions.Over recent decades,this methodology has been widely adopted to facilitate enantioselective nucleophilic addition reactions,including conjugate addition,Henry reaction,Mannich reaction,Strecker reaction,and hydrophosphonylation.This strategy has been successfully applied to the synthesis of numerous structurally diverse and multifunctionalized molecules,featuring challenging stereogenic centers.This minireview specifically highlights the accomplishments in asymmetric nucleophilic addition facilitated by chiral quaternary phosphonium catalysts.Its purpose is to cultivate interest among researchers,encouraging more engagement in this field and establishing quaternary phosphonium ion-pair catalysis as a potent and dependable tool for synthetic and pharmaceutical chemists.

Preparation and application of cationized pulp fiber as a papermaking wet-end additive

Cationized pulp fibers （CPF） were prepared by the adsorption of a novel biodegradable cationic ester quaternary ammonium salt （31441） on bleached softwood kraft pulp fibers. The optimized conditions for the CPF preparation were： 4% of 31441 （based on oven-dry pulp）, 80℃ and 30 rain. The CPF was characterized by FT-IR, SEM and XPS. Experimental results showed that the CPF improved the retention of precipitated calcium carbonate （PCC） filler significantly. With 0.9% CPF （based on oven-dry pulp）, the retention of PCC increased from 57.53% to 72.21%. The physical properties of paper were also slightly improved. The tensile strength and burst strength of the paper with CPF were higher than those with CPAM. CPF addition had no effect on the stock drainage.

Thermal stability and long-acting antibacterial activity of phosphonium montmorillonites

Na-montruorillonite （Na-MMT） was exchanged with three quaternary atkylphosphonium salts： decyl tributylphosphonium bromide （DTBPBr）, dodecyl tributylphosphonium bromide （DDTBPBr） and hexadecyl tributylphosphonium bromide （HDTBPBr）, to investigate the effects of phosphonium salts species and relative molecular mass on the characteristics, morphology, thermal stability and long-acting antibacterial property of phosphonium montmorillonites. The resulting modified montmorillonites were characterized by the FTIR, XRD, TEM, and TG/DTG techniques. And minimum inhibitory concentration （MIC） was used to investigate antibacterial activity. The results show that the phosphonium salts are intercalated into Na-MMT, and the basal spacing of P-MMTs is enlarged with the increase of phosphonium salt content or the growth of alkyl chain length. DDTBP-MMT-3 with 19.83% （mass fraction of dodecyl tributylphosphonium salts, displays excellent thermal stability and long-acting antibacterial activity.

Modified gelatin with quaternary ammonium salts containing epoxide groups

An EPDDMAC-GE polymer （hydrophilic molecule） has been synthesized based on epoxypropyl dodecyl dimethyl ammonium chloride （EPDDMAC） and gelatin. A DEEPSAC-GE polymer （hydrophobic molecule） has been synthesized based on diethyl-2,3-epoxypropyl-[3-methyldimethoxyl] silpropyl ammonium chloride （DEEPSAC） and gelatin. Compared with initial gelatin, the gelatin modified with quaternary ammonium salts containing epoxide groups exhibits stronger antibacterial activity.

Study on Reducing Injection Pressure of Low Permeability Reservoirs Characterized by High Temperature and High Salinity

In view of the problems of high injection pressure and low water injection rate in water injection wells of low permeability reservoirs featuring high temperature and high salinity,two new surfactants were synthesized,including a quaternary ammonium surfactant and a betaine amphoteric surfactant.The composite surfactant system BYJ-1 was formed by mixing two kinds of surfactants.The minimum interfacial tension between BYJ-1 solution and the crude oil could reach 1.4×10^(-3) mN/m.The temperature resistance was up to 140℃,and the salt resistance could reach up to 120 g/L.For the low permeability core fully saturated with water phase,BYJ-1 could obviously reduce the starting pressure gradient of low permeability core.While for the core with residual oil,BYJ-1 could obviously reduce the injection pressure and improve the oil recovery.Moreover,the field test showed that BYJ-1 could effectively reduce the injection pressure of the water injection well,increase the injection volume,and increase the liquid production and oil production of the corresponding production well.