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1.
Five novel phosphate-type hybrid surfactants, C mF 2m+1C 6H 4CH[OPO 2(OC 6H 5)Na]C nH 2n+1 (F mPH nPPhNa: m = 4, 6, 8; n = 3, 5; C 6H 4 = p-phenylene, C 6H 5 = phenyl), have been synthesized. When compared with sulfate-type hybrid surfactants, C mF 2m+1C 6H 4CH(OSO 3Na)C nH 2n+1 (C 6H 4 = p-phenylene), the new hybrid surfactants are found to have comparable abilities to lower surface tension of water. The critical micelle concentrations of F mPH nPPhNa follow Klevens rule and their occupied areas per molecule increase with increasing m and n. Calcium hydroxyapatite (CaHAp) pellets modified with F mPH3PPhNa gives high hydrophobic and lipophobic surfaces. The hybrid surfactants are expected as new dental reagents for oral hygiene. 相似文献
2.
To determine the analytical utility of photodissociation as a general fragmentation technique for tandem mass spectrometry of organic ions, the ability to fragment those ions considered least likely to absorb photons efficiently was investigated. To this end, the ability to photodissociate ions of aliphatic compounds by using 193-nm photons has been studied. Three fragment ions, the C 4H 9 + ion from n-hexane, the C 4H 7 + ion from 2-hexene, and C 4H 5 + from 2-hexyne, have been photodissociated. The fragmentation efficiencies for all three ions studied were between 25 and 45%. The photofragment ion spectrum for each precursor ion studied is made up of characteristic fragments. These spectra demonstrate the ability to photodissociate aliphatic ions that originate from both saturated and unsaturated molecules. This provides substantial hope that virtually all organic ions will be able to be photodissociated by using 193-nm photons. 相似文献
3.
Hydration of alkylammonium ions under nonanalytical electrospray ionization conditions has been found to yield cluster ions with more than 20 water molecules associated with the central ion. These cluster ion species are taken to be an approximation of the conditions in liquid water. Many of the alkylammonium cation mass spectra exhibit water cluster numbers that appear to be particularly favorable, i.e., “magic number clusters” (MNC). We have found MNC in hydrates of mono- and tetra-alkyl ammonium ions, NH 3(C m H 2m+1) +(H 2O) n , m=1–8 and N(C m H 2m+1) 4 + (H 2O) n , m=2–8. In contrast, NH 2(CH 3) 2 + (H 2O) n , NH(CH 3) 3 + (H 2O) n1 and N(CH 3) 4 + (H 2O) n do not exhibit any MNC. We conjecture that the structures of these magic number clusters correspond to exohedral structures in which the ion is situated on the surface of the water cage in contrast to the widely accepted caged ion structures of H 3O +(H 2O) n and NH 4 + (H 2O) n . 相似文献
4.
The positive APCI-mass spectra in air of linear ( n-pentane, n-hexane, n-heptane, n-octane), branched [2,4-dimethylpentane, 2,2-dimethylpentane and 2,2,4-trimethylpentane ( i-octane)], and cyclic (cyclohexane) alkanes were analyzed at different mixing ratios and temperatures. The effect of air humidity
was also investigated. Complex ion chemistry is observed as a result of the interplay of several different reagent ions, including
atmospheric ions O 2+•, NO +, H 3O +, and their hydrates, but also alkyl fragment ions derived from the alkanes. Some of these reactions are known from previous
selected ion/molecule reaction studies; others are so far unreported. The major ion formed from most alkanes (M) is the species
[M − H] +, which is accompanied by M +• only in the case of n-octane. Ionic fragments of C
n
H 2n
+1/+ composition are also observed, particularly with branched alkanes: the relative abundance of such fragments with respect
to that of [M − H] + decreases with increasing concentration of M, thus suggesting that they react with M via hydride abstraction. The branched
C 7 and C 8 alkanes react with NO + to form a C 4H 10NO + ion product, which upon collisional activation dissociates via HNO elimination. The structure of t-Bu +(HNO) is proposed for such species, which is reasonably formed from the original NO +(M) ion/molecule complex via hydride transfer and olefin elimination. Finally, linear alkanes C 5–C 8 give a product ion corresponding to C 4H 7+(M), which we suggest is attributed to addition of [M − H] + to C 4H 8 olefin formed in the charge-transfer-induced fragmentation of M. The results are relevant to applications of nonthermal plasma
processes in the fields of air depuration and combustion enhancement. 相似文献
5.
The photoionization and dissociative photoionization of m-xylene (C8H10) were researched by using synchrotron radiation vacuum ultraviolet (SR-VUV) and supersonic expanding molecular beam reflectron time-of-flight mass spectrometer (RFTOF-MS) system. The photoionization efficiency spectra (PIEs) of parent ion C8H10+ and main fragment ions C8H9+ and C7H7+ were observed, and the ionization energy (IE) of m-xylene and appearance energies (AEs) of main fragment ions C8H9+ and C7H7+ were determined to be 8.60 ± 0.03 eV, 11.76 ± 0.04 eV and 11.85 ± 0.05 eV, respectively. Structures of reactant, transition states (TSs), intermediates (INTs), and products involved in two dominant dissociation channels were optimized at the B3LYP/6-311++G(d,p) level, and the relative energies were calculated at the G3 level. Based on the results, two major dissociative photoionization channels, C7H7++CH3 and C8H9++H were calculated at the B3LYP/6-311++G(d,p) level. On the basis of theoretical and experimental results, the dissociative photoionization mechanisms of m-xylene were proposed. The C–H or C–C bond dissociation and hydrogen migration are the main processes in the dissociation channels of m-xylene cation. 相似文献
6.
Nine novel sulfate-type hybrid surfactants, C mF 2m+1C 6H 4CH(OSO 3Na)C nH 2n+1 (F mPH nOS: m=4, 6, 8; n=3, 5, 7; C 6H 4: p-phenylene), with a benzene ring in their molecules were synthesized. Alkanoyl chlorides were allowed to react with iodobenzene in the presence of aluminum chloride to give the corresponding aromatic ketones. The reaction of the ketones with perfluoroalkyl iodides yielded 1-[4-(perfluoroalkyl)phenyl]-1-alkanones as intermediates. The intermediates were allowed to react with methanol in tetrahydrofuran in the presence of sodium borohydride to yield 1-[4-(perfluoroalkyl)phenyl]-1-alkanols. The desired hybrid surfactants were obtained by the reaction of 1-[4-(perfluoroalkyl)phenyl-1-alkanols with sulfur trioxide/pyridine complex in pyridine and by the subsequent neutralization of the products with sodium hydroxide solution. When compared with the conventional hybrid surfactants, C mF 2m+1C 6H 4COCH(SO 3Na)C nH 2n+1 (F mH nS: m=4, 6; n=2, 4, 6; C 6H 4: p-phenylene), the new hybrid surfactants thus synthesized were found to have a comparable ability to lower the surface tension of water and a high hydrophilicity. The cmc of F mPH nOS obeyed Kleven’s rule and their occupied areas per molecule increased with increasing m and n with the values between 0.66 and 1.05 nm 2. The aggregation number for F mPH nOS micelles ranged from 6 to 45 and the hydrodynamic radius of the micelles was in the range of 1.4-3.1 nm. 相似文献
7.
The thermodynamic properties, PVTx ( TS, PS, ρS), (∂ P/∂ T) VX, and CVVTx, of three microemulsions (water + n-octane + sodium dodecylsulfate + 1-pentanol) with composition of solution-1: 0.0777 (H 2O):0.6997 ( n-C 8H 18):0.0777 (SDS):0.1449 (1-C 5H 11OH) mass fraction; solution-2: 0.6220 (H 2O):0.1555 ( n-C 8H 18):0.0777 (SDS):0.1448 (1-C 5H 11OH) mass fraction; and solution-3: 0.2720 (H 2O):0.5054 ( n-C 8H 18):0.0777 (SDS):0.1449 (1-C 5H 11OH) mass fraction were measured. Sodium dodecylsulfate (SDS) was used as an ionic surfactant, 1-pentanol used as stabilizer (cosurfactant), and n-octane as oil component in aqueous solution. A high-temperature, high-pressure, adiabatic, and nearly constant-volume calorimeter supplemented by quasi-static thermogram technique was used for the measurements. Measurements were made at eight densities (isochores) between 475.87 and 919.03 kg m −3. The range of temperature was from 275 to 536 K and pressure range was up to 138 bar. Uncertainty of the pressure, density, derivative (∂ P/∂ T) VX, and heat capacity measurements are estimated to be 0.25%, 0.02%, 0.12-1.5%, and 2.5%, respectively. Temperatures at liquid-gas phase transition curve, TS( ρ), for each measured densities (isochores) were determined using a quasi-static thermogram technique. The uncertainty of the phase transition temperature measurements is about ±0.02 K. The effect of temperature, density, and concentration on the heat capacity of the microemulsions is discussed. Along the isochore of 438.40 kg m −3 at temperatures above 525.44 K for the first solution the precipitation of the solid phase (SDS) was found. 相似文献
8.
Fast atom bombardment-produced [M + Na] + ions of tristearoylglycerol and [M ? H] ? ions of stearic or nervonic acid undergo charge-remote fragmentations (CRFs) to produce one series of product ions reflecting C n H 2n+2 losses, whereas electrospray ionization-produced ions fragment to give two series of product ions reflecting C n H 2n+2 and C n H 2n+1 losses. These results and those from previous studies show that the mechanisms and energetics of CRFs are complex and unsettled. We demonstrate that several pathways are simultaneously involved in CRFs, and the preference for certain pathways (by C n H 2n+1 and C n H 2n+2 losses) is determined by the internal energy of the compound itself and the ionization and activation energies that are applied to it. 相似文献
9.
Fe n + and Pd n + clusters up to n=19 and n=25, respectively, are produced in an external ion source by sputtering of the respective metal foils with Xe + primary ions at 20 keV. They are transferred to the ICR cell of a home-built Fourier transform mass spectrometer, where they are thermalized to nearly room temperature and stored for several tens of seconds. During this time, their reactions with a gas leaked in at low level are studied. Thus in the presence of ammonia, most Fe n + clusters react by simply adsorbing intact NH 3 molecules. Only Fe 4 + ions show dehydrogenation/adsorption to Fe 4(NH) m + intermediates ( m=1, 2) that in a complex scheme go on adsorbing complete NH 3 units. To clarify the reaction scheme, one has to isolate each species in the ion cell, which often requires the ejection of ions very close in mass. This led to the development of a special isolation technique that avoids the use of isotopically pure metal samples. Pd n + cluster ions ( n=2...9) dehydrogenate C 2H 4 in general to yield Pd n (C 2H 2) +, yet Pd 6 + appear totally unreactive. Towards D 2, Pd 7 + ions seem inert, whereas Pd 8 + adsorb up to two molecules. 相似文献
10.
Neutral benzene-ammonia clusters, prepared in a supersonic expansion, were ionized using multiphoton ionization. The cluster ions were investigated with a time-of-flight mass spectrometer. The observed major cluster ions, under 355-nm laser irradiation, resulting from prompt intracluster ion-molecule reaction and fragmentation following ionization are (C 6H 6) m(NH 3) nH +, m = 1–6, n = 1–4 and (C 6H 6) m+, m = 1–3. The results of isotopic labeling experiments clearly indicate that C 6H 6 does not participate in intracluster ion-molecule reactions to form (C 6H 6) m(NH 3) nH +. A local maximum appears at n = 2 in the intensity distribution of (C 6H 6) m(NH 3) nH + for each value of m under all experimental conditions. This finding indicates that (C 6H 6) m(NH 3) 2H + is more stable than any other (C 6H 5) m(NH 3) mH + (n = 1,3,4) for m = 1–6. 相似文献
11.
The binuclear cyclopalladated compounds [Pd 2(μ-OH) 2(L n) 2] ( 1) derived from imines HL n = p-C nH 2n + 1O-C 6H 4-CHN-C 6H 4-OC nH 2n + 1- p ( n = 6,10) react with carboxylic acids to give the derivatives [Pd 2(μ-ox) 2(L n) 2] ( 2) with a planar core for oxalic acid, and [Pd 2(μ-OOCR) 2(L n) 2] ( 3- 7) compounds with a non-planar ridge tent structure for other RCOOH acids: ( 3) R = C mH 2m + 1 ( m = 1, 3, 5, 7, 9, 11, 13, 15, 17); ( 4) R = CH 2(OCH 2CH 2) pOCH 3 ( p = 1, 2); ( 5) R = CH 2-C 6H 4-OC qH 2q + 1- p ( q = 2, 4, 6, 8, 10, 12); ( 6) R = C 6H 4-OC rH 2r + 1- p ( r = 4, 10); ( 7) R = C*H(OH)CH 3. The acids used were designed to explore the effect on the thermal properties of the compounds prepared of systematic variations in the type of carboxylato ligand, which induce structure, packing, and polarity changes, and in the length of the carboxylato chain. Most of the complexes prepared, even when far from planar, show liquid crystal behavior and display nematic, smectic A and smectic C phases. 相似文献
12.
In framework molecular cations and radical cations of adamantane C 10H
m
q+
and also in polyhedral molecules and molecular ions C 5H 5
+, C 6H 6
2
+, B 5H 9, and B 10H 10
2
-, the charge density of valence electrons in the central areas of C
n
and B
n
cavities and faces is significant. In the molecule of adamantane C 10H 16, the valence electron density in central areas of the cavity and faces of the C 10 framework is small as compared to the electron density along its edges C-C. These distinctions are due to the fact that, in the electronic structure of C
n
H
q
m
cations and radical cations and also of B
n
H
m
molecules and molecular ions, there is an additional orbital interaction involving vacant valence orbitals of C + or B (orbital-reduntant bonds); the absence of vacant valence orbitals of C atoms in neutral adamantane molecule excludes additional orbital interactions in excess of C-H and C-C. 相似文献
13.
Vacuum ultraviolet (VUV) dissociative photoionization of isoprene in the energy region 8.5–18 eV was investigated with photoionization mass spectroscopy (PIMS) using synchrotron radiation (SR). The ionization energy (IE) of isoprene as well as the appearance energies (AEs) of its fragment ions C 5H 7+, C 5H 5+, C 4H 5+, C 3H 6+, C 3H 5+, C 3H 4+, C 3H 3+ and C 2H 3+ were determined with photoionization efficiency (PIE) curves. The dissociation energies of some possible dissociation channels to produce those fragment ions were also determined experimentally. The total energies of C 5H 8 and its main fragments were calculated using the Gaussian 03 program and the Gaussian‐2 method. The IE of C 5H 8, the AEs for its fragment ions, and the dissociation energies to produce them were predicted using the high‐accuracy energy model. According to our results, the experimental dissociation energies were in reasonable agreement with the calculated values of the proposed photodissociation channels of C 5H 8. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
14.
From the mass-analysed ion kinetic energy spectra of labelled ions, kinetic energy releases and thermodynamic data, it is proved that protonated n-propylbenzene (1) isomerizes into protonated isopropyl benzene (2). It is also shown that the dissociation of the less energetic metastable ions of (2), leading to [iso-C 3H 7] + and [C 6H 7] + product ions, is preceded by H exchange. This H exchange involves two interconverting ion-neutral complexes [C 6H 6, iso-C 3H 7+] (2π) and [C 6H 7+, C 3H 6] (2α). 相似文献
15.
Anilines G n-{(C 6H 4)N(SiMe 3) 2} m, based on simple or dendritic carbosilanes, have been used to synthesized (imido)tantalum compounds G n-{(C 6H 4)NTaCl 2Cp ∗} m ( 1, n = 0, m = 1; 2, n = 1, m = 4; Cp ∗ = η5-C 5Me 5), by the reaction with [TaCl 4Cp ∗] and elimination of SiMe 3Cl. (Imido)niobocene compounds of general formula ( 3- 5; n = 0, 1, 2; m = 1, 4, 8, respectively) have been readily prepared from their corresponding half-sandwich complexes G n-{(C 6H 4)NNbCl 2Cp′} m by the reaction with m equiv. of LiCp′ (Cp′ = η5-C 5H 4SiMe 3). Compounds 1- 5 are all found to be exceedingly moisture sensitive, and in the case of the (imido)niobocene materials the hydrolytic reaction selectively leads to the formation of ( 6). The molecular structure of 6 has been determined by X-ray diffraction studies. 相似文献
16.
Theoretical calculations have been carried out to investigate the possible dissociation channels of isoprene. We focus on the major fragment ions of C 5H 7+,C 5H 5+,C 4H 5+,C 3H 6+,C 3H 5+,C 3H 4+,C 3H 3+ and C 2H 3+, which were observed experimentally from the isoprene dissociative photoionization. The energy calculations were performed with the CBS-QB3 model. All the geometries and energies of the fragments, intermediates and transition states involved in the dissociations channels were determined. Finally, the mechanisms of the dissociation pathways were discussed on the comparison of theoretical and experimental results. 相似文献
17.
Alkali metal, copper, nickel and rhodium complexes of alkylated [S 2COC 8H 17] and fluoroalkylated xanthate ligands [S 2COC mH 2mC nF 2n+1] ( m = 2, n = 4, 6; m = 3, n = 1, 8) have been prepared in high yields and characterised by elemental analysis, mass spectrometry, IR and NMR spectroscopies. The structures of [Cu(S 2COC 8H 17)(PPh 3) 2], [Cu(S 2COC 3H 6CF 3)(PPh 3) 2], [Ni(S 2COC 3H 6CF 3) 2], [Cp *RhCl(S 2COC 8H 17)] and [Cp *RhCl(S 2COC 3H 6CF 3)] have been determined by single crystal X-ray diffraction. 相似文献
18.
The (liquid + liquid) solubility curves have been determined by a synthetic method for six binary mixtures of [acetonitrile + {heptyl methyl ether CH 3O nC 7H 15, or ethyl hexyl ether C 2H 5O nC 6H 13, or pentyl propyl ether nC 3H 7O nC 5H 11, or isopentyl propyl ether nC 3H 7O i C 5H 11, or dibutyl ether nC 4H 9O nC 4H 9, or butyl isobutyl ether nC 4H 9O iC 4H 9}]. The possibility of the COSMO-SAC model to account for the thermodynamic differences between these systems has been tested and the discussion on the influence of screening charge of ethers on the system properties was undertaken. 相似文献
19.
Homoadamantane derivatives can be divided into two groups according to their mass spectra. To the first group belong compounds with electron attracting substituents (COOH, CI, COOCH 3, Br); compounds with electron releasing substituents (OCH 3, OH, NH 3, NHCOCH 3) constitute the second group. The most characteristic feature of the first group compounds is the splitting off of the substituent. The hydrocarbon fragment [C 11H 17] + thus formed then loses olefin molecules with the formation of corresponding ionic species C 11?nH 17?2n. The 3-substituted compounds of this group undergo thermal Wagner-Meerwein type rearrangements into adamantane derivatives, resulting in the [C 10H 15] + ( m/ e 135) ion formation; this is the main difference between 1- and 3-substituted homoadamantanes. The series of [C nH 2n?6X] + ions (where X = OCH 3, OH, NH 2, NHCOCH 3, n = 6 to 10) are characteristic of the mass spectra of the second group compounds, the ion [C 6H 6X] +, [M ? C 5H 11] + being the most abundant. The intensity ratio of [M ? C 5H 11] + to [M ? C 4H 9] + ions is 10:1 for 1-substituted and 3:1 for 3-substituted compounds of this group, allowing the location of the substituent. Some individual features of the spectra are also reported. 相似文献
20.
The vapour pressure of binary mixtures of hydrogen sulphide with ethane, propane, and n-butane was measured at T = 182.33 K covering most of the composition range. The excess Gibbs free energy of these mixtures has been derived from the measurements made. For the equimolar mixtures for (H 2S + C 2H 6), (820.1 ± 2.4) J · mol −1 for (H 2S + C 3H 8), and (818.6 ± 0.9) J · mol −1 for (H 2S + n-C 4H 10). The binary mixtures of H 2S with ethane and with propane exhibit azeotropes, but that with n-butane does not. 相似文献
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