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Ammonium Salts (ammonium + salt)
Kinds of Ammonium Salts Selected AbstractsSynthesis of the Ammonium Salt of 6-Amino-2-hydroxy- 3,5-dinitropyrazine and a Comparison of its Properties with those of Ammonium 3,5-Diaminopicrate (ADAP)PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 5 2009Anthony Abstract The ammonium salt of 6-amino-2-hydroxy-3,5-dinitropyrazine has been synthesised from 2,6-dimethoxy-3,5-dinitropyrazine and its properties (DSC, crystal structure, impact sensitiveness and thermochemical properties) are compared with the analogous benzene derivative, ammonium 3,5-diaminopicrate. [source] An Efficient Synthesis of Pyrroles by a One-Pot, Three-Component Condensation of a Carbonyl Compounds, an Amine and a Nitroalkene in a Molten Ammonium Salt.CHEMINFORM, Issue 27 2003Brindaban C. Ranu Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Enantioselective Michael Reaction of ,-Keto Esters Organocatalyzed by Recoverable Cinchona-Derived Dimeric Ammonium Salts.CHEMINFORM, Issue 22 2010Silvia Tari Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Inorganic Ammonium Salts as Catalysts for Direct Aldol Reactions in the Presence of Water.CHEMINFORM, Issue 15 2010Pawel Dziedzic Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis Utility of Ammonium Salts in a Cu-Catalyzed Three-Component Reaction as a Facile Coupling Partner.CHEMINFORM, Issue 18 2009Jinho Kim Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Selective Synthesis of Secondary and Tertiary Amines by Cp*Iridium-Catalyzed Multialkylation of Ammonium Salts with Alcohols.CHEMINFORM, Issue 26 2008Ryohei Yamaguchi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Enantioselective [1,2]-Stevens Rearrangement of Quaternary Ammonium Salts.CHEMINFORM, Issue 25 2008A Mechanistic Evaluation. Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] The Study of Cyclization of N-Acylphenacyl Anthranilates with Ammonium Salts under Various Conditions.CHEMINFORM, Issue 30 2007Pavel Hradil Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Asymmetric Phase-Transfer Catalysis of Homo- and Heterochiral Quaternary Ammonium Salts: Development and Application of Conformationally Flexible Chiral Phase-Transfer Catalysts.CHEMINFORM, Issue 10 2007Takashi Ooi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Highly Efficient Aza-Michael Reactions of Enones with Carbamates Using a Combination of Quaternary Ammonium Salts and BF3×OEt2 as a Catalyst.CHEMINFORM, Issue 15 2004Li-Wen Xu Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: A Dramatic Improvement of Epoxide Selectivity of [Ti,Al]-, by Ion-Exchange with Quaternary Ammonium Salts.CHEMINFORM, Issue 2 2002Yasuhide Goa Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ,N-Stereogenic Quaternary Ammonium Salts' from L -Amino Acids: Synthesis, Separation, and Absolute ConfigurationHELVETICA CHIMICA ACTA, Issue 4 2009Hua-Fang Wu Abstract Diastereoisomeric linear and cyclic ,N-chiral quaternary ammonium salts' (QASs) were efficiently synthesized from corresponding L -amino acids in high yields. The diastereoisomers of each pair of ,N-chiral QASs' were successfully separated. The absolute configurations of these QASs were determined predominately by X-ray single-crystal analysis. The 1H-NMR data of ,N-chiral QASs' provided characteristic information on the configuration of the N-chiral center. ,N-Chiral QASs' exemplified by [N(R)]- 2a and [N(S)]- 2a are stable in protic and aprotic solvents within a broad pH and temperature range. [source] Highly Enantioselective Synthesis of No-Carrier-Added 6-[18F]Fluoro- L -dopa by Chiral Phase-Transfer AlkylationEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2004Christian Lemaire Abstract [18F]Fluoro- L -dopa, an important radiopharmaceutical for positron emission tomography (PET), has been synthesized using a phase-transfer alkylation reaction. A chiral quaternary ammonium salt derived from a Cinchona alkaloid served as phase-transfer catalyst for the enantioselective alkylation of a glycine derivative. The active methylene group of this Schiff-base substrate was deprotonated with cesium hydroxide and rapidly alkylated by the 2-[18F]fluoro-4,5-dimethoxybenzyl halide (X = Br, I). The reaction proceeded with high yield (> 90%) at 0 °C or room temperature in various solvents such as toluene or dichloromethane. Preparation of the [18F]alkylating agent on a solid support was developed. After labelling, the labeled [18F]fluoroveratraldehyde was trapped on a tC18 cartridge and then converted on the cartridge into the corresponding benzyl halide derivatives by addition of aqueous sodium borohydride and gaseous hydrobromic or -iodic acid. Hydrolysis and purification by preparative HPLC made 6-[18F]fluoro- L -dopa ready for human injection in a 25,30% decay-corrected radiochemical yield in a synthesis time of 100 min. The product was found to be chemically, radiochemically and enantiomerically pure (ee > 95%). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] A flammability performance comparison between synthetic and natural clays in polystyrene nanocompositesFIRE AND MATERIALS, Issue 4 2005Alexander B. Morgan Abstract Polymer-clay nanocomposites are a newer class of flame retardant materials of interest due to their balance of mechanical, thermal and flammability properties. Much more work has been done with natural clays than with synthetic clays for nanocomposite flammability applications. There are advantages and disadvantages to both natural and synthetic clay use in a nanocomposite, and some of these, both fundamental and practical, will be discussed in this paper. To compare natural and synthetic clays in regards to polymer flammability, two clays were used. The natural clay was a US mined and refined montmorillonite, while the synthetic clay was a fluorinated synthetic mica. These two clays were used as inorganic clays for control experiments in polystyrene, and then converted into an organoclay by ion exchange with an alkyl ammonium salt. The organoclays were used to synthesize polystyrene nanocomposites by melt compounding. Each of the formulations was analysed by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). Flammability performance was measured by cone calorimeter. The data from the experiments show that the synthetic clay does slightly better at reducing the heat release rate (HRR) than the natural clay. However, all the samples, including the inorganic clay polystyrene microcomposites, showed a decreased time to ignition, with the actual nanocomposites showing the most marked decrease. The reason for this is postulated to be related to the thermal instability of the organoclay (via the quaternary alkyl ammonium). An additional experiment using a more thermally stable organoclay showed a time to ignition identical to that of the base polymer. Finally, it was shown that while polymer-clay nanocomposites (either synthetic or natural clay based) greatly reduce the HRR of a material, making it more fire safe, they do not provide ignition resistance by themselves, at least, at practical loadings. Specifically, the cone calorimeter HRR curve data appear to support that these nanocomposites continue to burn once ignited, rather than self-extinguish. Copyright © 2004 John Wiley & Sons, Ltd. [source] Functionalized 3,3,,5,5,-Tetraaryl-1,1,-Biphenyls: Novel Platforms for Molecular ReceptorsHELVETICA CHIMICA ACTA, Issue 3 2003Roger Welti This paper describes the development of novel aromatic platforms for supramolecular construction. By the Suzuki cross-coupling protocol, a variety of functionalized m- terphenyl derivatives were prepared (Schemes,1,4). Macrolactamization of bis(ammonium salt) (S,S)- 6 with bis(acyl halide) 7 afforded the macrocyclic receptor (S,S)- 2 (Scheme,1), which was shown by 1H-NMR titration studies to form ,nesting' complexes of moderate stability (Ka between 130 and 290,M,1, 300,K) with octyl glucosides 13,15 (Fig.,2) in the noncompetitive solvent CDCl3. Suzuki cross-coupling starting from 3,3,,5,5,-tetrabromo-1,1,-biphenyl provided access to a novel series of extended aromatic platforms (Scheme,5) for cleft-type (Fig.,1) and macrotricyclic receptors such as (S,S,S,S)- 1. Although mass-spectral evidence for the formation of (S,S,S,S)- 1 by macrolactamization between the two functionalized 3,3,,5,5,-tetraaryl-1,1,-biphenyl derivatives (S,S)- 33 and 36 was obtained, the 1H- and 13C-NMR spectra of purified material remained rather inconclusive with respect to both purity and constitution. The versatile access to the novel, differentially functionalized 3,3,,5,5,-tetrabromo-1,1,-biphenyl platforms should ensure their wide use in future supramolecular construction. [source] Kinetics of synthesis of bis-(benzoxazolyl-2-methyl) sulfide under phase-transfer catalysis conditionsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2009Zuo-Xiang Zeng Kinetics of synthesis of bis-(benzoxazolyl-2-methyl) sulfide (BBMS) is investigated under phase-transfer catalysis conditions. Thus, the reaction of 2-chloromethylbenzoxazole and sodium sulfide is carried out in a two-phase (organic/water) medium, and quaternary ammonium salt and quaternary phosphonium salt are used as phase-transfer catalyst (PTC) in the reaction. The conversion of 2-chloromethylbenzoxazole is dramatically enhanced by adding a small quantity of PTC and is also greatly affected by the reaction conditions. The effects of various reaction variables on the kinetics are investigated, including the amount of catalyst, the temperature, the kinds of catalysts, the kinds of solvents, and the agitation speed. An interfacial reaction mechanism is proposed to explain the characteristics of the reaction. A pseudo-first-order rate model is established to describe the relationship between the fractional conversion and the reaction time. The kinetics data demonstrate that the model is suitable to the reaction of synthesis of BBMS. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 296,302, 2009 [source] 3,5-Bis(n -perfluorooctyl)benzyltriethylammonium Bromide (F-TEBA): An Efficient, Easily Recoverable Fluorous Catalyst for Solid-Liquid PTC ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Gianluca Pozzi Abstract A readily available 3,5-bis(perfluorooctyl)benzyl bromide and triethylamine were reacted under mild conditions to give 3,5-bis(n -perfluorooctyl)benzyltriethylammonium bromide (F-TEBA), an analogue of the versatile phase-transfer catalyst, benzyltriethylammonium chloride (TEBA), containing two fluorous ponytails. This perfluoroalkylated quaternary ammonium salt was successfully employed as a catalyst in a variety of reactions run under solid-liquid phase-transfer catalysis (SL-PTC) conditions. Thus, being both hydrophobic and lipophobic, F-TEBA could be quickly recovered in quantitative yields, and reused without loss of activity over several reaction cycles. [source] Properties of amylopectin/montmorillonite composite films containing a coupling agentJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007D. Nordqvist Abstract The addition of clay to polymers has the combined effects of enhancing both the strength/stiffness and the barrier properties. This investigation presents a novel approach to further enhance the strength/stiffness of cast plasticized amylopectin (AP)/Na+ -montmorillonite clay films using a water-soluble coupling agent, poly[(isobutylene- alt -maleic acid, ammonium salt)- co -(isobutylene- alt -maleic anhydride)], between the filler and the matrix. The addition of clay increased the strength and stiffness of the film and the addition of 0.4 parts of a coupling agent per 1 part clay further increased these properties. The trends were the same after each treatment, and there were always significant differences in stiffness and strength between the films without clay and with clay with 0.4 parts of the coupling agent. The increase in stiffness/strength in the presence of a small amount of the coupling agent suggested that it had a bridging effect, presumably through strong secondary bonds to the clay and to the matrix. Infrared spectroscopy and moisture swelling experiments indicated that ester bonds were formed between the coupling agent and AP. X-ray spectroscopy and transmission electron microscopy revealed that the clay-particle/polymer structure was qualitatively independent of the presence of the coupling agent showing a mixture of intercalated clay stacks and exfoliated platelets. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4160,4167, 2007 [source] Catalytic kinetics of quaternary ammonium poly(styrene- co -methylstyrene) resinAICHE JOURNAL, Issue 7 2006Ho-Shing Wu Abstract The catalytic kinetics and synthesis of poly(styrene- co -chloromethylstyrene) resin of different degrees of crosslinkages and ring substitutions were investigated by copolymerizing styrene and chloromethylstyrene through crosslinking with divinylbenzene. Poly(styrene- co -chloromethylstyrene) quaternary ammonium salt was obtained with activating poly(styrene- co -chloromethylstyrene) resin with tertiary amine. More than 20 types of poly(styrene- co -chloromethylstyrene) quaternary ammonium catalyst were prepared, with reaction conditions including immobilized time (0.125,4 days), concentration of tertiary amine (0.1,2 kmol/m3), kinds of solvents in immobilization (methanol, ethyl alcohol, and DMF), and kinds of tertiary amines (trimethylamine, triethylamine, tripropylamine, tri- n -butylamine, tri- n -pentylamine, tri- n -hexylamine, and tri- n -octylamine). These catalysts were used to achieve the optimum allylation of phenol. The reactions were conducted and studied individually with either equal mole or equal weight of catalyst. The best reactivity for the allylation of phenol was obtained when the structure of the quaternary ammonium catalyst was 10% degree of ring substitution and 2% degree of crosslinkage activating with trihexylamine. The turnover number and the effectiveness factor were also calculated. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source] Comparison of the Effects of an Ionic Liquid and Other Salts on the Properties of Electrospun Fibers, 2 , Poly(vinyl alcohol)MACROMOLECULAR MATERIALS & ENGINEERING, Issue 1 2009Ganesh Kumar Arumugam Abstract Understanding the effect of conductivity in electrospinning solutions is crucial in order to improve or control the electrospinning process. In this paper the effect of adding small amounts (0.039,0.259 mol,·,kg,1) of three different conductive additives to aqueous solutions of polyvinyl alcohol has been investigated. The salts were HMICl (a room temperature ionic liquid), TEBAC (a quaternary ammonium salt) and KCl. Addition of these salts caused a steady increase in the solution conductivity but the fiber diameter was typically greater than that of PVA alone, and exhibited an oscillatory trend. The oscillatory trend on the fiber diameter is attributed to fiber backbuilding and fusion that occurs prior to deposition on the collector. [source] Organo-vermiculite structure ordering after PVAc introductionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2007yna Simha Martynková Abstract Natural vermiculite served as a host for intercalation with quaternary ammonium salt (QUAT) followed by in-situ polymerization of polyvinyl acetate (PVAc). We studied the structural changes of organo-vermiculite and its PVAc nanocomposite with the help of X-ray diffraction analysis. The mean crystallite size of PVAc nanocomposite is double compared to that of organo-vermiculite and its distribution of crystallite sizes presents a broader region but more uniform values than the curve calculated for organo-vermiculite. Molecular dynamic calculation proved a monolayer arrangement of QUAT guests and a bilayer-like system of guest organic molecules in the vermiculite gallery. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Solid-state linear viscoelastic properties of intercalated poly(L -lactide)/organo-modified montmorillonite hybridsPOLYMER INTERNATIONAL, Issue 8 2006Pham Hoai Nam Abstract Hybrids of poly(L -lactide)/organophilic clay (PLACHs) have been prepared by a melt-compounding process using poly(L -lactide) (PLLA) and different contents of surface-treated montmorillonite modified with a dimethyl dioctadecyl ammonium salt. The dispersion structures of clay particles in PLACHs were investigated using wide-angle X-ray diffraction and transmission electron microscopy. The solid-state linear viscoelastic properties for these PLACHs were examined as functions of temperature and frequency. The incorporation of organo-modified silicate into PLLA matrix enhanced significantly both storage moduli (E,) and loss moduli (E,). The strong enhancement observed in dynamic moduli of PLACHs could be attributed to uniformly dispersed state of the clay particles with high aspect ratio (= length/thickness of clay) and the intercalation of the PLLA chains between silicate layers. Copyright © 2006 Society of Chemical Industry [source] Quantitative determination of perfluorooctanoic acid ammonium salt in human serum by high-performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2002Cristina Sottani A sensitive, specific, accurate and reproducible analytical method was developed and validated to quantify perfluorooctanoic acid (PFOA) in human serum. After initial extraction with an ion-paring reagent, the procedure for quantifying PFOA is based on high-performance liquid chromatography (HPLC) interfaced to negative ion tandem mass spectrometry, operating in selected ion monitoring mode. The retention times of PFOA and its internal standard (D,L-malic acid) were 5.85 and 1.70,min, respectively. The assay was linear over the range 0,500,ng/mL, with a lower limit of quantification (LOQ) of 25,ng/mL, and with a coefficient of variation (CV) of 7.3%. The lower limit of detection (LOD) was assessed as 10,ng/mL. The overall precision and accuracy were assessed on three different days. The within- and between-day precision was ,9.7 and 6.8%, respectively, and the accuracy was in the range 96,114%. The mean extracted recovery assessed at three different concentrations (100, 250, and 500,ng/mL) was always more than 85%. With this method no derivatization procedure was needed, thus avoiding possible thermal and chemical decomposition reactions of PFOA. The assay was applied to quantify perfluorooctanoic acid in serum from employees exposed to fluorochemicals commonly used in industrial applications for polymer production. The quantitative results for PFOA blood levels were found to vary between 100 and 982,ng/mL. Copyright © 2002 John Wiley & Sons, Ltd. [source] CH-Directed Anion,, Interactions in the Crystals of Pentafluorobenzyl-Substituted Ammonium and Pyridinium SaltsCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2010Markus Albrecht Prof. Abstract Simple pentafluorobenzyl-substituted ammonium and pyridinium salts with different anions can be easily obtained by treatment of the parent amine or pyridine with the respective pentafluorobenzyl halide. Hexafluorophosphate is introduced as the anion by salt metathesis. In the case of the ammonium salt 4, water co-crystallisation seems to suppress effective anion,, interactions of bromide with the electron-deficient aromatic system, whereas with salts 5 and 6 such interactions are observed despite the presence of water. However, due to asymmetric hydrogen-bonding interactions with ammonium side chains, the anion of 5 is located close to the rim of the pentafluorophenyl group (,1 interaction). In 6 the CH,anion hydrogen bonding is more symmetric and fixes the anion on top of the ring (,6). A similar structure-controlling effect is observed in case of the 1,4-diazabicyclo[2.2.2]octane derivatives 7. Here the position of the anion (Cl, Br, I) is shifted according to the length of the weak CH,halide interaction. The hexafluorophosphate 7,d reveals that this "non-coordinating" anion can be located on top of an aromatic , system. In the methyl-substituted pyridinium salts 9 and 10 different locations of the bromide anions with respect to the , system are observed. This is due to different conformations of the mono- versus disubstituted pyridine, which leads to different directions of the weak, but structurally important, HMeBr bonds. [source] Novel Anion Exchangers for Electrodes with Improved Selectivity to Divalent AnionsELECTROANALYSIS, Issue 17 2004Vladimir Egorov Abstract It has been found that replacing of several long-chain alkyl substituents at the nitrogen atom of lipophilic quaternary ammonium salts (QAS) by methyls results in a dramatic increase of the potentiometric selectivity of ion-selective electrodes (ISE) with QAS-based plasticized PVC membranes to some divalent anions against the monovalent ones. The discussed effect of QAS cation nature on the potentiometric selectivity is also partly retained for ISE with neutral carrier-based membranes doped with QAS to provide anion permselectivity. This opens up new possibilities to control the potentiometric selectivity of ISE for divalent anions by the appropriate selection of the anion exchanger. [source] Stereochemical Models for Discussing Additions to ,,, -Unsaturated Aldehydes Organocatalyzed by Diarylprolinol or Imidazolidinone Derivatives , Is There an ,(E)/(Z)-Dilemma'?HELVETICA CHIMICA ACTA, Issue 4 2010Dieter Seebach Abstract The structures of iminium salts formed from diarylprolinol or imidazolidinone derivatives and ,,, -unsaturated aldehydes have been studied by X-ray powder diffraction (Fig.,1), single-crystal X-ray analyses (Table,1), NMR spectroscopy (Tables,2 and 3, Figs.,2,7), and DFT calculations (Helv. Chim. Acta2009, 92, 1, 1225, 2010, 93, 1; Angew. Chem., Int. Ed.2009, 48, 3065). Almost all iminium salts of this type exist in solution as diastereoisomeric mixtures with (E)- and (Z)-configured +NC bond geometries. In this study, (E)/(Z) ratios ranging from 88,:,12 up to 98,:,2 (Tables,2 and 3) and (E)/(Z) interconversions (Figs.,2,7) were observed. Furthermore, the relative rates, at which the (E)- and (Z)-isomers are formed from ammonium salts and ,,, -unsaturated aldehydes, were found to differ from the (E)/(Z) equilibrium ratio in at least two cases (Figs.,4 and 5,,a, and Fig.,6,,a); more (Z)-isomer is formed kinetically than corresponding to its equilibrium fraction. Given that the enantiomeric product ratios observed in reactions mediated by organocatalysts of this type are often ,99,:,1, the (E)-iminium-ion intermediates are proposed to react with nucleophiles faster than the (Z)-isomers (Scheme,5 and Fig.,8). Possible reasons for the higher reactivity of (E)-iminium ions (Figs.,8 and 9) and for the kinetic preference of (Z)-iminium-ion formation are discussed (Scheme,4). The results of related density functional theory (DFT) calculations are also reported (Figs.,10,13 and Table,4). [source] Synthesis of novel 1,3-substituted 1H -[1,2,4]-triazole-3-thiol derivativesHETEROATOM CHEMISTRY, Issue 7 2009Karine A. Eliazyan By means of regioselective S-alkylation of 1H-1,2,4-triazole-3-thiol (1), a series of S-substituted derivatives 2a-j were synthesized. In certain conditions, the reaction of 2 with arylsulfochlorides, arylisocyanates, and quaternary ammonium salts of azines corresponding compounds were obtained 1-arylsulfonyl- (3a-d), 1-arylcarbonamido- (4a,b), and 1-azinyl-1,2,4- (6a-p) triazoles. Structures of compounds were confirmed by 1H NMR and elemental analyses. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 20:405,410, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20565 [source] Tetrakis(trimethysilyl)hypophosphate P2O2(OTMS)4: Synthesis, reactivity and application as flame retardantHETEROATOM CHEMISTRY, Issue 7 2007Catherine Ruflin The preparation of tetrakis(trimethy- silyl)hypophosphate, P2O2(OTMS)4 (TMS = SiMe3), which is easily obtained from cheap starting materials, is reported. Reaction with protic substrates (H2O, alcohols) proceeds under stepwise cleavage of silylethers, ROTMS, and formation of hypophosphoric acid, P2O2(OH)4. Amines in the presence of molecular sieves lead to desilylation and formation of ammonium salts of the [P2O2(OTMS)2(O,)2] dianion. On cotton fabrics, P2O2(OTMS)4 hydrolyzes to give P2O2(OH)4 within about 1 h when exposed to air, and this compound acts as an efficient flame retardant (limiting oxygen index >26%) even at low loadings (P content <3%). © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:721,731, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20373 [source] Antibacterial activity of novel insoluble bead-shaped polymer-supported multiquaternary ammonium saltsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010E. Murugan Abstract This study describes the effect of antibacterial activity of newly reported five different novel insoluble bead-shaped polymer-supported multiquaternary ammonium salts (PM quats) viz., bis-quat, tris-quat (2 Nos.), tetrakis-quat, hexakis-quat containing two, three, four, and six quaternary ammonium groups, respectively. The presence of number of quaternary ammonium groups in each salt was established already through Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and chloride ion analyzes. The antibacterial activities of these five different PM quats against three different bacteria viz., Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa were investigated by serial dilution and spread plate method and compared the same with a monoquat containing single quaternary ammonium group. The extent of antibacterial activity has been measured in terms of colony forming units (CFU) at different time intervals. The observed results show that all the PM quats exhibited excellent-antibacterial activity against each bacterium. On the basis of the CFU values, the antibacterial activity was found to increase from bis-quat to hexakis-quat, which reveals that the activity of PM quats increases with increase in the number of quaternary ammonium groups. The mechanism of interaction of quats with bacterial cytoplasmic membrane has been explained as an adsorption-like phenomenon. The reusability of highly active hexakis-quat against Staphylococcus aureus was studied and the activity was found to reduce after first cycle. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Polyesters based on two silarylene or germarylene moieties: Synthesis under phase-transfer conditionsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2009L. H. Tagle Abstract Polyesters (PEs) containing two heteroatoms (Si and/or Ge) in the main chain, derived from the acid dichlorides bis(4-chloroformylphenyl) ethylmethylsilane, bis(4-chloroformylphenyl) diethylsilane, bis(4-chloroformylphenyl) diethylgermane, and bis(4-chloroformylphenyl) di- nbutylgermane and from the diphenols bis(4-hydroxyphenyl) ethylmethylsilane, bis(4-hydroxyphenyl) diethylsilane, bis(4-hydroxyphenyl) diethylgermane, and bis(4-hydroxyphenyl) di- nbutylgermane, were synthesized under phase-transfer conditions with three quaternary ammonium salts as phase-transfer catalysts and three NaOH concentrations in the aqueous phase. PEs were characterized with IR and NMR spectroscopy, including 29Si-NMR. In general, the yields and intrinsic viscosities were low, and in some cases, an increase in these parameters was shown as a result of the catalyst effect. An increase in the NaOH concentration caused a decrease in the yields because of a hydrolytic process. PEs with Si were thermally more stable than those with Ge. The glass-transition temperatures decreased when the side chains bonded to the heteroatoms were longer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] | ||||||||||||||||||||||||||||||||||