Effect Of Quaternary Ammonium Salts Research Articles

Influence of clay on the vulcanization kinetics of fluoroelastomer nanocomposites

The vulcanization kinetics of gum and montmorillonite (Na-MMT) clay filled fluoroelatomer (FKM) nanocomposite was studied using both oscillating disc rheometer and differential scanning calorimetry under isothermal and dynamic conditions. The X-ray diffraction pattern of clay filled FKM showed a shift in d-spacing toward higher values indicating the formation of intercalated silicate layer. The cure characterization showed higher rate and state of vulcanization of modified clay filled compound than that of gum and unmodified clay filled FKM indicating the accelerating effect of quaternary ammonium salt modified clay. Although the unmodified clay slowed down the cure reaction, there was marked increase in cure rate at higher level of curative. Higher loading of clay decreased the cure rate with lowering of maximum torque values. The presence of organoclay increased the torque value through the formation of confined elastomer network within the silicate galleries. The experimental data obtained provided the evidence that the curing behavior illustrated autocatalytic characteristics. The kinetic parameters determined from the model equation had good agreement with the experimental results. The calculated activation energy of the gum and clay filled systems indicated the ease of cure process with respect to the type of clay. The cure kinetics measured by different methods was well correlated with each other.

HYDROLYSIS OF ETHYL-2-BROMOISOBUTYRATE ESTER IN AN ALKALINE SOLUTION

The hydrolysis of ethyl-2-bromoisobutyrate in an alkaline solution/organic solvent two-phase medium as well as the effect of quaternary ammonium salt (e.g., tetrabutylammonium bromide) on the hydrolysis of ethyl-2-bromoisobutyrate were investigated in this work. The proposed mechanism for the hydrolysis of ethyl-2-bromoisobutyrate was verified based on experimental analysis. Both the bromo-alkyl (Br-C bond) and ester (-COOR) functional groups of ethyl-2-bromo-isobutyrate hydrolyze into alcohol and acid. Several reaction steps for the hydrolysis of these bromo-alkyl and ester functional groups were developed and discussed. A kinetic model of each reaction step was developed in which the rate expression was derived. The intrinsic rate constants of the reactions were determined from the experimental hydrolyzing data of ethyl-2-bromoisobutyrate using curving fitting. The effects of the reaction conditions on the conversion of reactants were investigated in detail. The results indicated that the conversion of reactants is highly dependent on the concentration of alkaline compound in the aqueous solution. An optimum value of alkaline concentration to produce a maximum conversion of reactant was obtained. Moreover, the conditions for reducing the hydrolysis of halo ester by adding sodium carbonate are recommended.

Peroxy derivatives of epoxy resins based on bisphenol A: Effects of quaternary ammonium salts

Oligomers containing peroxy groups have been synthesized on the basis of epoxides and organic hydroperoxides. Dependence of reaction rates upon the ratio of starting materials, nature, quantity, concentration of ammonium salt catalysts, temperature and also nature of hydroperoxides have been investigated. Activation energies and effective rate constants of reactions between hydroperoxides and epoxy resins were calculated. The reaction proceeds by interfacial catalysis, and therefore with poor yields in solvents which are miscible with water (acetone and 1.4-dioxane) and with good yields in immiscible solvents (chloroform and toluene). Structures of the synthesized peroxy oligomers have been confirmed by IR-spectroscopy.

In Situ Studies of Cu Deposition in the Presence of Quaternary Ammonium Salts

The effect of quaternary ammonium salts on the electrodeposition of Cu from acidified sulfate solutions on Au(111) single‐crystal electrodes was studied with in situ atomic force microscopy, electrochemical, and X‐ray diffraction techniques. Cyclic voltammetry showed that hexadecyltrimethylammonium bromide adsorbs strongly on the Au substrate, thus inhibiting Cu deposition both in the underpotential deposited (upd) and bulk deposition region. Cu electrodeposits formed in the presence of were found to consist of regularly shaped triangular crystallites, whose orientation was influenced by the topographical characteristics of the Au substrate. The distinctive morphology was attributed to the combined presence of and . The Cu crystallites were observed to form in a layer‐by‐layer fashion, and the frequency of layer formation and lateral growth rate were found to depend on the applied overpotential. A one‐dimensional transport model was used in order to assess the adatom concentration on the growing crystallites and to provide qualitative insight into the deposit growth habit.

Effect of Quaternary Ammonium Salts on Carrier-Mediated Transport of Lanthanide Ions through Cellulose Triacetate Membranes

Abstract Fluxes of all lanthanides, except promethium, across cellulose triacetate membranes were determined by using mixtures of o-nitrophenyl n-octyl ether and quaternary ammonium salts as plasticizers, and 4-benzoyl-3-methyl-1-phenyl-5-pyrazolone (BMPP) and 4-trifluoroacetyl-3-methyl-1-phenyl-5-pyrazolone (TMPP) as carriers. The quaternary ammonium salts used were didodecyldimethyl-, distearyldimethyl-, tetrahexyl-, tetraoctyl-, and tetradecylammonium bromides [referred to as (C12)2NBr, (C18)2NBr, (C6)4NBr, (C8)4NBr, and (C10)4NBr, respectively]. The effect of these ammonium bromides on the flux was demonstrated. For membranes containing 0.1 M (C12)2NBr and (C18)2NBr, BMPP exhibited considerably high fluxes. The fluxes of lanthanum and cerium using BMPP for (C12)2NBr were higher than those of the other lanthanides. For the membranes containing 0.5 M (C12)2NBr and 0.1 M (C18)2NBr, however, no difference in flux among the lanthanides was observed. The fluxes using TMPP for (C12)2NBr and (C18)2NBr were very small, with the exception of some lanthanides. Appreciably high fluxes were observed for membranes containing 0.1 M (C6)4NBr using BMPP. For (C8)4NBr and (C10)4NBr, BMPP exhibited low fluxes. For these membranes using TMPP, the lanthanides were scarcely transported.

Effects of quaternary ammonium salts on membrane potential and electric conductance in internodal cells of Nitettopsis obtusa

Effects of amphiphilic derivatives of glycine esters of the general formula (CH3)3N+CH2COOCnH2n+1Cl‐ (n = 10, 12, 14, 16) on membrane potential and conductance in internodal cells of the alga Nitellopsis obtusa were studied. The compounds decreased the potential difference between vacuole and external medium and increased the electric conductance. The effects depended on the length of the alkyl chain (n) and the concentration of these quaternary ammonium salts. Light‐induced hyperpolarization was suppressed by the salts. We suggest that the ammonium salts inhibit the electrogenic proton pump in the plasmalemma and enhance the passive efflux of Cl‐ from the algal cell.

Effects of quaternary ammonium salts on membrane potential and electric conductance in internodal cells of Nitellopsis obtusa

Effects of quaternary ammonium salts on membrane potential and electric conductance in internodal cells of Nitellopsis obtusa

The catalytic effect of quaternary ammonium salt On the Extraction of Palladium(II) With 2-Hydroxy-5-Nonyi-Benzophenone Oxime(LIX 65N) In Heptane-Chloroform Solvents

ABSTRACT Extraction of Pd(II) from acidic chloride media using 2-hydroxy-5-nonyi-benzophenone oxime (LIX 65N,KL) in heptane is 60% more rapid than that using chloroform under comparable conditions, as well as more complete, reflecting an eight-fold increase in the extraction constant. A further substantial increase in the ex traction rate was achieved using the quaternary ammonium sait, Aliquat 336S, without any change in the extraction constant. The extraction probaly occurs through rapid phase transfer of PdCl via ion pair extraction followed by formation of the chelate, PdL2-, in the organic phase.

The Effect of Quaternary Ammonium Salts on Electro‐oxidation of Benzhydrol

A study was made of the effect of tetra‐alkylammonium salts on the anodic oxidation of benzhydrol using potential pulse and galvanostatic pulse techniques. The results of the studies were in agreement with the interpretation that, in addition to solubilization effects, the primary cause of the increased yields is the formation of a film on the surface, which excludes side reactions with water. Potential pulse studies were in agreement with the previous conclusion that this film undergoes reorganization at a potential around −0.6V vs. SCE. The galvanostatic pulse studies showed that it requires a cathodic current pulse to destroy this film in a short time.

Pulse radiolysis study of salt effects on reactions of aromatic radical cations with Cl–. Rate constants in the absence and presence of quaternary ammonium salts

The effect of quaternary ammonium salts on the decays of the radical cations of biphenyl, trans-stilbene, anthracene and pyrene generated by pulse radiolysis in chlorohydrocarbons has been investigated. The decays, which are due to neutralization reactions with Cl–, are retarded by the addition of salts having non-nucleophilic PF–6, BF–4 and ClO–4, whereas the radical cations are rapidly quenched by salts having I– and BPh–4. The retarding effect of the salts is attributed to the formation of ion pairs between the reacting ions and the counter-ions from the salts. The rate constants for the neutralization reactions in 1,2-dichloroethane have been determined for the free-ion and ion-paired states; the latter state is attained by the addition of Bu4NPF6. The rate constants for the reactions of the radical cations except for Py·+(Py = pyrene) are in the ranges (1.3–1.9)× 1011 dm3 mol–1 s–1 for the free ions and (2.8–7.0)× 1010 dm3 mol–1 s–1 for the ion pairs. The rate constant determined in the absence of the salt for Py·+ is one order of magnitude smaller than those for the others. The salt effect is also smallest on the reaction of Py·+. The charge delocalization of the large aromatic radical cation may be responsible for the exceptional results for Py·+. The largest salt effect was observed on the reaction of Ph2CH+, a charge-localized carbenium ion investigated for comparison. The solvent effect on the neutralization reactions is also discussed.

Enhanced Methylation of Sodium Carboxylates in Methyl Ethyl Ketone. the Effect of Quaternary Ammonium Salt

Abstract The methylation of sodium carboxylates in methyl ethyl Ketone (MEK) in the presance of quaternary ammonium salt is described.

The effect of quaternary ammonium salts on the anodic oxidation of ethanol

A study was made of the effect of additives on the rate of deactivation of platinized platinum in the anodic oxidation of ethanol in order to determine whether additives that form a hydrophobic layer on platinum would protect against normal poisoning processes. The data were interpreted in terms of a mechanism in which the oxidation of the alcohol proceeded at different rates on the bare and inhibited surface in a reaction that was zero order with respect to alcohol and first order with respect to the areas of each type of surface, while the inhibition reaction was second order with respect to the fraction of the surface that was bare. Without additives this mechanism agreed with data at 0.9 V (measured with respect to a saturated calomel electrode) but at 0.5 V the contribution from the inhibited route was negligible and the rate became approximately independent of the area on the more heavily platinized surfaces. Tetrabutylammonium perchlorate did not influence any of the rate constants, indicating that it was not adsorbed on the platinum. Solutions containing chlorides caused marked decreases in the rates of oxidation on the bare surface, but at 0.9 V caused only small decreases in the rate of oxidation on the inhibited surface, indicating that chlorides are only weakly adsorbed on the inhibited surface. The addition of a large quaternary ion together with the chlorides increased the effect of the chloride, confirming the fact that these salts acted by ion pairing with the adsorbed chloride. None of the additives had a significant effect on the rate of poisoning of the electrode at 0.5 V. At 0.9 V neither sodium chloride nor tetrabutylammonium perchlorate affected the rate of inhibition, but the addition of tetrabutylammonium perchlorate to the sodium chloride or the use of the commercial surfactant Hyamine 3500 (a large quaternary ammonium chloride) caused significant decreases in the rate of the inhibition reaction.

Effect of quaternary ammonium salts on spectrophotometric characteristic of pyrogallol red and bromopyrogallol red

The spectrophotometric characteristic and acid-base properties of pyrogallol red and bromopyrogallol red in the absence and presence of quaternary ammonium salts are described. The presence of quaternary ammonium salts changes the dissociation of reagent to a more acid region. The bathochromic shift of absorption spectra of PR and BPR is dependent on the length of the hydrocarbon radical but is strongly dependent on the hydrophilic group of quaternary ammonium salt.

Effects of quaternary ammonium salts on reactions of aromatic radical anions formed in tetrahydrofuran by pulse radiolysis

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffects of quaternary ammonium salts on reactions of aromatic radical anions formed in tetrahydrofuran by pulse radiolysisYukio Yamamoto, Shoichi Nishida, Katsuyoshi Yabe, Koichiro Hayashi, Seishi Takeda, and Kunihiko TsumoriCite this: J. Phys. Chem. 1984, 88, 11, 2368–2372Publication Date (Print):May 1, 1984Publication History Published online1 May 2002Published inissue 1 May 1984https://doi.org/10.1021/j150655a037RIGHTS & PERMISSIONSArticle Views142Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (558 KB) Get e-Alerts

Oxidation of polyunsaturated ethers and esters by molecular oxygen catalyzed by palladium salts

1. A study was carried out on the oxidation of polyunsaturated ethers and esters by molecular oxygen catalyzed by the PdCl2-CuCl system. A series of new mono-, di-, and triketoethers and triketoesters was obtained in high yield. 2. A synergistic effect of quaternary ammonium salts was found in the oxidation by molecular O2 leading to an increase in the yield of carbonyl compounds.

Flocculation Effect of Quaternary Ammonium Salts of Poly [2- (N, N dimethylamino) ethyl Methacrylate] on Kaolin Suspension

Quaternary ammonium salts of poly [2- (N, N-dimethylamino) ethyl methacrylate] (cationic polymer) were prepared by the reaction of poly [2- (N, N- dimethylamino) ethyl methacrylate] (PAEM) with various alkyl bromides with a view of obtaining good flocculants. The flocculating ability for aqueous suspensions of kaolin was investigated with respect to the structure of quaternary ammonium salt polymers by measuring the sedimentation velocity, sedimentation volume, and residual turbidity.The results obtained are as follows.1) The sedimentation velocity of cationic polymer (QPC2X) prepared from PAEM and ethyl bromide was independent of the degree of quaternization and maximum sedimentation velocity showed 3.03.2 cm/min. Of other cationic polymers (QPC6X, QPC12X, QPC18X) obtained from PAEM and higher alkyl bromides (hexyl bromide, dodecyl bromide, and stearyl bromide), cationic polymers of the lower degree of quaternization displayed the larger rate of sedimentation and the maximum rate of sedimentation showed 2.33.2 cm/min at the optimum dosage of 610 ppm. 2) The bulky precipitation was obtained with cationic polymer of the medium degree of quaternization (5070%). 3) The clearest supernatant gave 2550 ppm turbidity at the dosage of 810 ppm. 4) Cationic polymers were most effective for flocculation with the increase of acidity. 5) The sedimentation velocity decreased rapidly at the concentration of 2.55.0% of kaolin suspension. 6) Cationic polymers derived from PAEM and various alkyl bromides were more effective with the commercial flocculants such as Sumifloc-FC, Himoloc-Neo 600, and PAS-A.

Sulfated acid mucopolysaccharides in the cortical granules of eggs: Effects of quaternary ammonium salts on fertilization

Sulfated acid mucopolysaccharides have been shown to be constituents of cortical granules in sea urchin and vertebrate eggs. These observations were made possible by retaining soluble acid mucopolysaccharides in situ within the eggs by precipitation during fixation with cetyltrimethyl-ammonium bromide, a quaternary ammonium salt. The sulfated mucopolysaccharides were then identified by staining with Astrablau at pH 0.2 and also by reaction with sodium rhodizonate. Staining reaction with Alcian blue at pH 2.5 showed that carboxylated mucopolysaccharides may also be present in cortical granules. The natural ionic environment of these eggs would favor the formation of very stable complexes between sulfated mucopolysaccharides and quaternary ammonium salts. Brief exposure of unfertilized sea urchin eggs to several quaternary ammonium compounds produced a residual adverse effect on subsequent fertilization in terms of increased vulnerability to polyspermy and reduced fertilizability. These results suggest that sulfated acid mucopolysaccharides participate in the function of the cortical granules and the establishment of the block to polyspermy at fertilization, and possibly in other cellular secretory processes.

Mechanism of polymerization of ring-compounds containing nitrogen

The detailed mechanism of the polymerization of ring-compounds containing nitrogen, namely, 1-azabicyclo-(3,1,0)-hexane (ABH) conidine, quinuclidine and triethylene diamine has been investigated in the present work under the effect of quaternary ammonium salts, ammonium salts and the BF 3·conidine complex. It has been shown that the active sites for the polymerization of the monomers are ions and ion pairs; the activity of ion pairs is comparable with or greater than the activity of the free ions. The effect of the nature of the counter-ion, cation and the polarity of the medium on the reaction rate has been studied. It has been established that the polymerization rate depends on the nature of the counter-ion for polymerization by ion pairs and does not depend on the counter-ion for polymerization by free ions. The reaction rate increases in proportion to the size of the counter-ion for polymerization by ion pairs. The enthalpy changes have been measured for the ring compounds containing nitrogen and these have been correlated with the activation energies.

Selective effect of quaternary ammonium salts on the activity of arylaminopeptidases of the dental pulp, and on trypsin, chymotrypsin and leucine aminopeptidase.

Selective effect of quaternary ammonium salts on the activity of arylaminopeptidases of the dental pulp, and on trypsin, chymotrypsin and leucine aminopeptidase.

The change in acid strength of acidic dye molecule and organic ligand on the micelle surface.

The interaction between acidic dye molecule and positive charges on the micelle surface has been investigated. The protolytic dissociation of acidic dye molecule containing a hydroxyl group on one end of the conjugated system and nitro or carbonyl group on the other end is promoted on the micelle surface. The interaction between dipole of acidic dye molecule and positive charges on the micelle surface causes a transfer of an electron from the electrondonating group to the electron-attracting group. The effect of quaternary ammonium salt on the acid strength increases with the increase of the dissociation constant of hydroxyl group on the dye molecule. The increase of ionic strength and the decrease of dielectric constant weaken the interaction. With the quaternary ammonium salt, the lower the critical micelle concentration, the stronger is the interaction between dye molecule and micelle. Dye molecules or ligands involving -SO3H group are liable to be absorbed on the micelle surface. It is found that the complexes of higher order are readily formed on the micelle surface, and the analytical sensitivity increases if the absorption of the complex is due to π→π* transition of organic ligands.