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1.
A method of ion-pair chromatography was developed on a reversed-phase silica-based monolithic column for the fast and simultaneous determination of trifluoromethanesulfonate (CF 3SO 3 ?) and p-toluenesulfonate (C 7H 7SO 3 ?). The analysis was performed using a mobile phase of tetrabutylammonium hydroxide?+?citric acid?+?acetonitrile on the Chromolith Speed ROD RP-18e column with direct conductivity detection. The effects of the eluent, column temperature and flow rate on the retention of the anions were investigated. The experimental phenomenon was discussed according to hydrophobic interaction and ion-exchange mechanism in the separation. The optimized chromatographic conditions were selected. The optimized eluent for the separation consisted of 0.2?mmol?L ?1 tetrabutylammonium hydroxide?+?0.10?mmol?L ?1 citric acid?+?9% acetonitrile (pH 5.5). The flow rate was set at 6.0?mL?min ?1. The column temperature was 25???C. Under the optimal conditions, the better separation of CF 3SO 3 ? and C 7H 7SO 3 ? was achieved without any interference by other anions (Cl ?, Br ?, I ?, NO 3 ?, SO 4 2?, ClO 3 ?, BF 4 ? and PF 6 ?). The detection limit (S/N?=?3) was 0.28 and 0.71?mg?L ?1 for CF 3SO 3 ? and C 7H 7SO 3 ?, respectively. The method has been applied to the determination of CF 3SO 3 ? and C 7H 7SO 3 ? in ionic liquids. The spiked recoveries of CF 3SO 3 ? and C 7H 7SO 3 ? were 101.1 and 100.2%, respectively. 相似文献
2.
An investigation was carried out into the fast determination of five homologue imidazolium cations in ionic liquids by ion chromatography using a cation-exchange column and direct conductivity detection. Ethylenediamine, complex organic acid (citric acid, oxalic acid and tartaric acid) and organic modifiers (acetonitrile) were used as mobile phase. The influences of the eluent types, eluent concentration, eluent pH and column temperature on separation of the cations were discussed. Simultaneous separation and determination of the five homologue imidazolium cations in ionic liquids were achieved under an optimum condition. The optimized mobile phase was consisted of 0.25 mmol L ?1 ethylenediamine + 0.5 mmol L ?1 citric acid + 3% acetonitrile ( v/ v) (pH 4.1), set at a flow rate of 1.0 mL min ?1. The column temperature was 40 °C and detection limits were obtained in the range of 1.1–45.6 mg L ?1. The relative standard deviations of the chromatographic peak areas for the cations were <3.0% ( n = 5). This method was successfully applied to separate imidazolium cations in ionic liquids produced by organic synthesis. The recoveries of spiked components were 92.5–101.9%. 相似文献
3.
Ion-interaction chromatography with direct conductivity detection has been used for analysis of nitrate and nitrite. Chromatographic separation was performed on a monolithic silica-based C 18 column dynamically modified with tetrabutylammonium (TBA +). Using the optimized mobile phase, containing 2.0 mmol L ?1 TBA + and 0.8 mmol L ?1 citrate (pH 6.0), delivered at a flow rate of 6.0 mL min ?1, separation of five anions (chloride, nitrite, bromide, nitrate, and sulfate) was achieved in only 40 s at a column temperature of 30 °C. The detection limits for nitrate and nitrite were 0.74 and 0.92 mg L ?1, respectively. The relative standard deviation (RSD, n = 5) of the retention times of nitrate and nitrite was 0.1% and RSD of chromatographic peak areas were 0.4 and 0.2%, respectively. The method was successfully used for analysis of the anions in groundwater. Recovery of nitrate and nitrite was 99.1 and 105%, respectively. 相似文献
4.
A simple and mild method for the determination of fatty acids (C1 – C10) based on a condensation reaction using 7-aminonaphthalene-1,3-disulfonic acid (ANDSA) as labeling reagent with capillary zone electrophoresis has been developed. The detection was performed with a diode array detector at 254 nm. A 58.5 cm × 50 μm i.d. (50 cm effective length) untreated fused-silica capillary was used. To optimize the separation conditions, the background electrolyte concentration, column temperature, voltage and other factors were evaluated. The optimal separation conditions were as follows: 30 mmol L−1 borate buffer (pH 9.5), 15 mmol L−1 β-CD, temperature at 20 °C, pressure 50 mbar and injection time 8 s. Under the established conditions, 10 fatty acid derivatives could be well-separated within 17 min. The linearity was in the range of 0.07–5.0 μmol L−1. Detection limits (at a signal-to-noise ratio of 3) were in the range of 0.027–0.042 μmol L−1. The fatty acids from the extracted Funaria Hedw. and Selaginella samples were determined with satisfactory results. 相似文献
5.
Reactions of Li + [( η5-C 5H 5)Re(NO)(PPh 3)] − with 2- and 4-chloroquinoline or 1-chloroisoquinoline give the corresponding σ quinolinyl and isoquinolinyl complexes 3 , 6 , and 8 . With 3 and 8 there is further protonation to yield HCl adducts, but additions of KH give the free bases. Treatment of 3 with HBF 4⋅OEt 2 or H(OEt 2) 2+ BAr f− gives the quinolinium salts [( η5-C 5H 5)Re(NO)(PPh 3)(C(NH)C(CH) 4C (CH)(CH))] + X − ( 3-H + X −; X −=BF 4−/BAr f−, 94–98 %). Addition of CF 3SO 3CH 3 to 3 , 6 , or 8 affords the corresponding N-methyl quinolinium salts. In the case of [( η5-C 5H 5)Re(NO)(PPh 3)(C(NCH 3)C(CH) 4C (CH)(CH))] + CF 3SO 3− ( 3-CH 3 + CF 3SO 3−), addition of CH 3Li gives the dihydroquinolinium complex ( SReRC, RReSC)-[( η5-C 5H 5)Re(NO)(PPh 3)(C(NCH 3)C(CH) 4C (CHCH 3)(CH 2))] + CF 3SO 3− (( SReRC, RReSC)- 5 + CF 3SO 3−, 76 %) in diastereomerically pure form. Crystal structures of 3-H + BAr f−, 3-CH 3 + CF 3SO 3−, ( SReRC, RReSC)- 5 + Cl −, and 6-CH 3 + CF 3SO 3− show that the quinolinium ligands adopt Re⋅⋅⋅ C conformations that maximize overlap of their acceptor orbitals with the rhenium fragment HOMO, minimize steric interactions with the bulky PPh 3 ligand, and promote various π interactions. NMR experiments establish the Brønsted basicity order 3 > 8 > 6 , with Ka(BH +) values >10 orders of magnitude greater than the parent heterocycles, although they remain less active nucleophilic catalysts in the reactions tested. DFT calculations provide additional insights regarding Re⋅⋅⋅ C bonding and conformations, basicities, and the stereochemistry of CH 3Li addition. 相似文献
6.
In this study the application of various surfactant agents on the performance of HFRLM for uranium transfer was investigated. Using Taguchi experimental design in recycling mode of HFRLM, maximum uranium recovery of 63.17% was obtained at 0.15 mol L ?1 H 2SO 4, 0.0125 mol L ?1 Alamine 336 and 0.25 mol L ?1 NH 4Cl in the donor, liquid membrane and acceptor phase, respectively. Also, the continuous mode experiments were conducted and HFRLM stability was compared with HFSLM. The uranium transfer would be improved by adding 0.05 mmol L ?1 of SDS, CTAB and LAE-7 to the donor phase and 10 mmol L ?1 of CTAB and LAE-7 to the acceptor phase. 相似文献
7.
Crystals of the title compound, C 4H 8N 5+·C 2F 3O 2−, are built up of singly protonated 2,4‐diamino‐6‐methyl‐1,3,5‐triazin‐1‐ium cations and trifluoroacetate anions. The CF 3 group of the anion is disordered. The oppositely charged ions interact via almost linear N—H...O hydrogen bonds, forming a CF 3COO −...C 4H 8N 5+ unit. Two units related by an inversion centre interact through a pair of N—H...N hydrogen bonds, forming planar (CF 3COO −...C 4H 8N 5+...C 4H 8N 5+·CF 3COO −) aggregates that are linked by a pair of N—H...O hydrogen bonds into chains running along the c axis. 相似文献
8.
The salts 3‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium saccharinate, C 9H 10F 4NO +·C 7H 4NO 3S −, (1), and 3‐[(2,2,3,3,3‐pentafluoropropoxy)methyl]pyridinium saccharinate, C 9H 9F 5NO +·C 7H 4NO 3S −, (2), i.e. saccharinate (or 1,1‐dioxo‐1λ 6,2‐benzothiazol‐3‐olate) salts of pyridinium with –CH 2OCH 2CF 2CF 2H and –CH 2OCH 2CF 2CF 3meta substituents, respectively, were investigated crystallographically in order to compare their fluorine‐related weak interactions in the solid state. Both salts demonstrate a stable synthon formed by the pyridinium cation and the saccharinate anion, in which a seven‐membered ring reveals a double hydrogen‐bonding pattern. The twist between the pyridinium plane and the saccharinate plane in (2) is 21.26 (8)° and that in (1) is 8.03 (6)°. Both salts also show stacks of alternating cation–anion π‐interactions. The layer distances, calculated from the centroid of the saccharinate plane to the neighbouring pyridinium planes, above and below, are 3.406 (2) and 3.517 (2) Å in (1), and 3.409 (3) and 3.458 (3) Å in (2). 相似文献
9.
The crystal structures of four substituted‐ammonium dichloride dodecachlorohexasilanes are presented. Each is crystallized with a different cation and one of the structures contains a benzene solvent molecule: bis(tetraethylammonium) dichloride dodecachlorohexasilane, 2C 8H 20N +·2Cl −·Cl 12Si 6, (I), tetrabutylammonium tributylmethylammonium dichloride dodecachlorohexasilane, C 16H 36N +·C 13H 30N +·2Cl −·Cl 12Si 6, (II), bis(tetrabutylammonium) dichloride dodecachlorohexasilane benzene disolvate, 2C 16H 36N +·2Cl −·Cl 12Si 6·2C 6H 6, (III), and bis(benzyltriphenylphosphonium) dichloride dodecachlorohexasilane, 2C 25H 22P +·2Cl −·Cl 12Si 6, (IV). In all four structures, the dodecachlorohexasilane ring is located on a crystallographic centre of inversion. The geometry of the dichloride dodecachlorohexasilanes in the different structures is almost the same, irrespective of the cocrystallized cation and solvent. However, the crystal structure of the parent dodecachlorohexasilane molecule shows that this molecule adopts a chair conformation. In (IV), the P atom and the benzyl group of the cation are disordered over two sites, with a site‐occupation factor of 0.560 (5) for the major‐occupied site. 相似文献
10.
The bonding geometry of sulfur in the cations of the title compounds, C 8H 11S +·CF 3SO 3? and C 13H 13S +·CF 3SO 3?, respectively, is similar and is independent of the ratio of the Me/Ph substituents. As expected, in both cations, the S—Ph bonds are somewhat shorter than the S—Me bonds. In both crystal structures, the interaction between cations and anions is similar. 相似文献
11.
In acid-media ([H +] = 0.01–0.06 M), each of the thiol compounds, D-penicillamine (PEN, L PH 2) and captopril (CAP, L CH 2) exist in several proton-dependent forms which can reduce the superoxo complex [(en)(dien)Co III(O 2)Co III(en)(dien)] 5+ ( 1) to the corresponding peroxo [(en)(dien)Co III(O 2)Co III(en)(dien)] 4+ ( 2) or the hydroperoxo complex [(en)(dien)Co III(OOH)Co III(en)(dien)] 5+ ( 3). The observed first-order rate constants, ko,P and ko,C for PEN and CAP increase with the increase in [T PEN] and [T CAP] (which are the analytical concentrations of the respective thiols) but decrease with the increase in the media-acidity ([H +]) and the media ionic strength ( I). The protolytic equilibria in aqueous solution allow several potentially reducing forms to coexist for both PEN (L PH 3+, L PH 2, L PH ?, and L P2?) and CAP (L CH 2, L CH ?, L C2?) but the kinetic analyses reveal that the order of reactivity for the species are L PH 3+ ~ L PH 2 <<< L PH ? and L CH 2 < L CH ? <<< L C2?, respectively. The predominance and higher reactivities of the anionic species, L PH ? and L C2? are supported by the negative slopes of the plots of ko,P or ko,C versus I. Moreover, a large value of kH/ kD for PEN suggests an inner-sphere electroprotic reaction pathway while the absence of such effect for CAP strongly supports an outer-sphere electron transfer reaction. These propositions are supported by the structural features of L PH ? and L C2?. 相似文献
12.
The reaction of xenonbis(trifluoroacetate) and trifluoromethanesulfonic acid (triflic acid) gave the new, highly reactive unsymmetrical xenon-oxo species CF 3COOXeOSO 2CF 3. Benzene derivates, containing electron withdrawing substituents such as -F, -CF 3, -Cl or -NO 2 were electrophilic attacked by this intermediate to yield arylxenon trifluoromethanesulfonates. Via this one-pot synthesis trifluoromethanesulfonates with the cations [Xe(2,4,6-F 3C 6H 2)] +, [Xe(2-F-5-NO 2C 6H 3)] +, [Xe(2-F-5-CF 3C 6H 3)] + and [Xe(3,5-(CF 3) 2C 6H 3)] + were prepared. All compounds were characterized by their NMR, mass, and vibrational spectra. Additionally, several new arylxenon trifluoromethanesulfonates were detected by 129Xe-NMR spectroscopy as products of the reaction of 1,3-F 2C 6H 4 and further deactivated benzenes with xenontrifluoroacetate trifluoromethane sulfonate. Fluoro substituents in ortho position to xenon significantly increase the thermal stability of the arylxenon trifluoromethanesulfonates obtained. The molecular structure of [Xe(2,6-F 2C 6H 3)][OSO 2CF 3] was determined by single crystal diffraction methods. The arylxenon unit is weakly coordinated by one oxygen atom of the CF 3SO 3 anion. The salt crystallizes in the triclinic space group P1 , a = 880.9(3) pm, b = 1093.9(5) pm, c = 1209.8(5) pm, α = 89.04(4)°, β = 74.23(3)°, γ = 86.03(3)°, Z = 4. 相似文献
13.
Hydrazinium saccharinate, N 2H 5+·C 7H 4NO 3S −, crystallizes in a 1:1 ratio, while ethylenediaminium bis(saccharinate), C 2H 10N 22+·2C 7H 4NO 3S −, and butane‐1,4‐diaminium bis(saccharinate), C 4H 14N 22+·2C 7H 4NO 3S −, form in a 1:2 cation–anion stoichiometry. The structures contain many strong hydrogen bonds of the N +—H⋯N −, N +—H⋯O, N—H⋯O and N—H⋯N types, with auxiliary C—H⋯O interactions. 相似文献
14.
A representative series of diphosphine monophosphonium salts [1‐Ph 2P(C 10H 6)‐8‐PRPh 2] +X – ( 2 b : R = H, X = CF 3SO 3; 4 : R = Me, X = CF 3SO 3; 5 : R = C 6H 5CH 2 = Bn, X = Br) has been prepared by treatment of 1,8‐bis(diphenylphosphino)naphthalene (dppn, 1 ) with stoichiometric amounts of HSO 3CF 3 or CH 3SO 3CF 3 in CH 2Cl 2 at +20 °C and with C 6H 5CH 2Br in toluene at +80 °C. Their X‐ray crystal structures show that there is no evidence for dative P → P + interactions. Instead, steric repulsion deflects the substituent groups to opposite faces of the naphthalene plane [splay angles: +11.4° ( 2 b ), +13.6° ( 4 ); +16.7° ( 5 )]. In solution 2 b , 4 , and 5 were dynamic according to 31P, 13C, and 1H NMR spectroscopy. The fluxionality of 2 b involves rapid intramolecular proton exchange between the two phosphorus atoms, which slows down at low temperature, whereas the dynamic behaviour of 4 and 5 is interpreted in terms of hindered rotation of the bulky RPh 2P + groups (R = Me or Bn) about the P–C(naphthyl) bond. Treatment of 1,8‐bis(diphenylphosphoryl)naphthalene (dppnO 2, 6 ) with HSO 3CF 3 gave the protonated bis(phosphine oxide), as the triflate salt, dppnO 2H + CF 3SO 3– ( 7 ). The X‐ray structure analysis of 7 revealed a highly strained molecule (P1…P2 365.5 pm) in which the P=O bonds point to the same face of the naphthalene plane to accommodate the proton. All isolated compounds were characterised by a combination of 31P, 1H, and 13C NMR spectroscopy, IR spectroscopy ( 7 ), mass spectrometry and elemental analysis. 相似文献
15.
Two inclusion compounds of dithiobiurea and tetrapropylammonium and tetrabutylammonium are characterized and reported, namely tetrapropylammonium carbamothioyl(carbamothioylamino)azanide, C 12H 28N +·C 2H 5N 4S 2−, (1), and tetrabutylammonium carbamothioyl(carbamothioylamino)azanide, C 16H 36N +·C 2H 5N 4S 2−, (2). The results show that in (1), the dithiobiurea anion forms a dimer via N—H...N hydrogen bonds and the dimers are connected into wide hydrogen‐bonded ribbons. The guest tetrapropylammonium cation changes its character to become the host molecule, generating pseudo‐channels containing the aforementioned ribbons by C—H...S contacts, yielding the three‐dimensional network structure. In comparison, in (2), the dithiobiurea anions are linked via N—H...S interactions, producing one‐dimensional chains which pack to generate two‐dimensional hydrogen‐bonded layers. These layers accommodate the guest tetrabutylammonium cations, resulting in a sandwich‐like layer structure with host–guest C—H...S contacts. 相似文献
16.
Four organic salts, namely benzamidinidium orotate (2,6‐dioxo‐1,2,3,6‐tetrahydropyrimidine‐4‐carboxylate) hemihydrate, C 7H 9N 2+·C 5H 3N 2O 4−·0.5H 2O (BenzamH +·Or −), (I), benzamidinium isoorotate (2,4‐dioxo‐1,2,3,4‐tetrahydropyrimidine‐5‐carboxylate) trihydrate, C 7H 9N 2+·C 5H 3N 2O 4−·3H 2O (BenzamH +·Isor −), (II), benzamidinium diliturate (5‐nitro‐2,6‐dioxo‐1,2,3,6‐tetrahydropyrimidin‐4‐olate) dihydrate, C 7H 9N 2+·C 4H 2N 3O 5−·2H 2O (BenzamH +·Dil −), (III), and benzamidinium 5‐nitrouracilate (5‐nitro‐2,4‐dioxo‐1,2,3,4‐tetrahydropyrimidin‐1‐ide), C 7H 9N 2+·C 4H 2N 3O 4− (BenzamH +·Nit −), (IV), have been synthesized by a reaction between benzamidine (benzenecarboximidamide or Benzam) and the appropriate carboxylic acid. Proton transfer occurs to the benzamidine imino N atom. In all four acid–base adducts, the asymmetric unit consists of one tautomeric aminooxo anion (Or −, Isor −, Dil − and Nit −) and one monoprotonated benzamidinium cation (BenzamH +), plus one‐half (which lies across a twofold axis), three and two solvent water molecules in (I), (II) and (III), respectively. Due to the presence of protonated benzamidine, these acid–base complexes form supramolecular synthons characterized by N +—H...O − and N +—H...N − (±)‐charge‐assisted hydrogen bonds (CAHB). 相似文献
17.
The title compound, [Cu(C 2N 3)(C 12H 8N 2) 2](CF 3SO 3), is formed by discrete [Cu(phen) 2{N(CN) 2)}] + complex cations (phen is 1,10‐phenanthroline) and uncoordinated CF 3SO 3− anions. The Cu centre is five‐coordinated in the form of a distorted trigonal bipyramid to two phen molecules and one dicyanamide ligand, which is coordinated through one nitrile N atom in the equatorial plane at a distance of 1.990 (2) Å. The two axial Cu—N distances are similar (mean 1.993 Å) and are substantially shorter than the two equatorial Cu—N bonds (mean 2.125 Å). 相似文献
18.
Basic Metals. LXIV. Lewis-basic Bis(trimethylphosphine)cobalt Complexes with Indenyl and Trifluormethylcyclopentadienyl as Ligands The half-sandwich type compounds C 9H 7Co(PMe 3) 2 ( 1 ) and (C 5H 4CF 3)Co(PMe 3) 2 ( 6 ) are prepared from CoCl(PMe 3) 3 and C 9H 7Li or TlC 5H 4CF 3, respectively. They behave like metal bases and react with HBF 4, CH 3I (or CF 3SO 3CH 3), I 2, and CH 3COCl by oxidative addition to give the cationic complexes [C 9H 7CoX(PMe 3) 2] + and [(C 5H 4CF 3)CoX(PMe 3) 2] + (X ? H, CH 3, I, COCH 3) which are isolated as the PF 6 salts ( 2–5 and 7–10 ). The 1HNMR and the IR spectra of the compounds 1–10 are discussed, also in comparison to those of the corresponding cyclopentadienylcobalt complexes. 相似文献
19.
Positive singly charged ionic liquid aggregates [(C nmim) m+1(BF 4) m] + (mim = 3‐methylimidazolium; n = 2, 4, 8 and 10) and [(C 4mim) m+1(A) m] + (A = Cl −, BF 4−, PF 6−, CF 3SO 3− and (CF 3SO 2) 2N −) were investigated by electrospray ionisation mass spectrometry and energy‐variable collision induced dissociation. The electrospray ionisation mass spectra (ESI‐MS) showed the formation of an aggregate with extra stability for m = 4 for all the ionic liquids with the exception of [C 4mim][CF 3SO 3]. ESI‐MS‐MS and breakdown curves of aggregate ions showed that their dissociation occurred by loss of neutral species ([C nmim][A]) a with a ≥ 1. Variable‐energy collision induced dissociation of each aggregate from m = 1 to m = 8 for all the ionic liquids studied enabled the determination of Ecm, 1/2 values, whose variation with m showed that the monomers were always kinetically much more stable than the larger aggregates, independently of the nature of cation and anion. The centre‐of‐mass energy values correlate well with literature data on ionic volumes and interaction and hydrogen bond energies. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
20.
The reduction of iodine by hydroxylamine within the [H +] range 3×10 −1–3×10 −4 mol.L −1 was first studied until completion of the reaction. In most cases, the concentration of iodine decreased monotonically. However, within a narrow range of reagent concentrations ([NH 3OH +] 0/[I 2] 0 ratio below 15, [H +] around 0.1 mol.L −1, and ionic strength around 0.1 mol.L −1), the [I 2] and [I 3−] vs. time curves showed 2 and 3 extrema, respectively. This peculiar phenomenon is discussed using a 4 reaction scheme (I 2+I −⇔︁I 3−, 2 I 2+NH 3OH ++H 2O→HNO 2+4 I −+5 H +, NH 3OH ++HNO 2→N 2O+2 H 2O+H +, and 2 HNO 2+2 I −+2 H +→2 NO+I 2+2 H 2O). In a flow reactor, sustained oscillations in redox potential were recorded with an extremely long period (around 24 h). The kinetics of the reaction was then investigated in the starting conditions. The proposed rate equation points out a reinforcement of the inhibition by hydrogen ions when [H +] is above 4×10 −2 mol.L −1 at 25°C. A mechanism based on ion-transfer reactions is postulated. It involves both NH 2OH and NH 3OH + as the reducing reactive species. The additional rate suppression by H + at low pH would be connected to the existence of H 2OI + in the reactive medium. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 785–797, 1998 相似文献
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