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1.
Excess molar enthalpies HE and excess molar volumes VE have been measured, as a function of mole fraction x1, at 298.15 K and atmospheric pressure for the five liquid mixtures ( x11,4-C 6H 4F 2 + x2n-C lH 2l+2), l = 7, 8, 10, 12 and 16. In addition, HE and excess molar heat capacities CPE at constant pressure have been determined for the two liquid mixtures ( x1C 6F 6 + x2n-C lH 2l+2), l = 7 and 14, at the same temperature and pressure. The instruments used were flow microcalorimeters of the Picker design (the HE version was equipped with separators) and a vibrating-tube densimeter, respectively. The excess enthalpies of the five difluorobenzene mixtures are all positive and quite large; they increase with increasing chain length l of the n-alkane from HE(x1 = 0.5)/(J mol−1) = 1050 for l = 7 to 1359 for l = 16. The corresponding excess volumes VE are all positive and also increase with increasing l: VE(x1 = 0.5)/(cm3 mol−1) = 0.650 for l = 7 and 1.080 for l = 16. Interestingly, the excess enthalphies of the corresponding mixtures with hexafluorobenzene are only about 5% larger, whereas the excess volumes of (x1C6F6 + x2n-ClH2l+2) are roughly twice as large as those of their counterparts in the series containing 1,4-C6H4F2. Specifically, at 298.15 K HE(x1 = 0.5)/(J mol−1) = 1119 for (x1C6F6 + x2n-C7H16) and 1324 for (x1C6F6 + x2n-C14H30), and for the same mixtures VE(x1 = 0.5)/(cm3 mol−1) = 1.882 and 2.093, respectively. The excess heat capacities for both systems are negative and of about the same magnitude as the excess heat capacities of mixtures of fluorobenzene with the same n-alkanes (Roux et al., 1984): CPE(x1 = 0.5)/(J K−1 mol−1) = −1.18 for (x1C6F6 + x2n-C7H16), and −2.25 for (x1C6F6 + x2n-C14H30). The curve CPE vs. (x1 for x1C6F6 + x2n-C14H30) shows a sort of “hump” for x1 0.5, which is presumed to indicate emerging W-shape composition dependence at lower temperatures. 相似文献
2.
Excess molar volumes, VE, and partial molar volumes,
i, have been calculated for binary liquid mixtures of anisole with bromobenzene, o-dichlorobenzene, o-chloroaniline and p-dioxane from the results of densities measured at 298.15, 303.15, 308.15 and 313.15 K over the entire range of composition. In the temperature interval studied the values of VE are positive for anisole + p-dioxane, anisole + bromobenzene and anisole + o-dichlorobenzene, whereas negative values are observed for anisole + o-chloroaniline. The negative VE for the latter system was due to specific interactions between mixing components. The positive VE for the remaining systems was ascribed to the dispersion-type interactions. 相似文献
3.
Rate coefficients for the reactions of cyclohexadienyl ( c-C 6H 7) radicals with O 2 and NO were measured at 296 ± 2 K. The c-C 6H 7 radicals were detected selectively by laser-induced fluorescence. The rate coefficient for the reaction of c-C 6H 7 with O 2, (4.4 ± 0.5) × 10 −14 cm 3 molecule −1 s −1, was independent of the bath-gas (He) pressure (13–80 Torr). In the reaction of c-C 6H 7 with NO, thermal equilibrium among c-C 6H 7, NO, and C 6H 7NO was observed. The forward and reverse reactions were in the falloff region, and the equilibrium constant was (1.5 ± 0.6) × 10 −15 cm 3 molecule −1. 相似文献
4.
Dilatometric measurements of excess volume VE and ultrasonic speed u have been carried out for mixtures of mono-, di-, tri- and tetra(ethylene glycol)s in pyrrolidin-2-one (PY) over the whole mole fraction range at 303.15 K. In the mixture of PY and monoethylene glycol, the VE is positive except for slight negative variation at the high mole fraction of PY. The other three mixtures PY + di-, + tri- and + tetra(ethylene glycol)s show negative VE over the entire composition range in the order di- u with increase in the mole fraction of PY in the case of monoethylene glycol while for other three systems u rises. From these measurements, partial molar quantities ViE and KS,iE have been calculated and analysed. Estimates of isentropic molar quantity KS equal to −(∂V/∂p)S and its excess counterpart KSE have also been computed. The KSE is positive for mono-, and negative for all the other mixtures over the whole composition range. 相似文献
5.
New experimental data were published in literature regarding CCl 4, C 2HCl 3 and C 2H 5Cl decomposition in dry air under electron beam influence. Taking into account experimental data theoretical models of those species decomposition were established and computer simulations were performed by the authors of this work to find the kinetics of such processes. The results of the calculations and experimental data show that CCl 4 decomposition depends on delivered dose and initial CCl 4 concentrations. The calculation revealed that recombination of CCl +4 and Cl − is the source of CCl 3 radicals and that reaction may have an important role in the process of CCl 4 decomposition. A theoretical model of C 2HCl 3 decomposition in dry air under electron beam influence describes the decay of C 2HCl 3 and the formation of several products such as Cl 2, CCl 2O, CO, CO 2, HCl and C 2HCl 3O. The detailed comparison of experimental and theoretical data shows relatively good agreement in efficiency of C 2HCl 3 decomposition process, but it can be achieved only with an assumption that the relation between rate constants of C 2HCl 4O intermediate product decomposition (C 2HCl 3O+Cl and COCl 2+CHCl 2) should be around 20 and C 2HCl 3O oxidation rate should be not lower than 7.5×10 −11 cm 3/mols. All those rate constants are not yet established experimentally. The results of the calculation of C 2H 5Cl decomposition and the data obtained experimentally were compared. The temperature, gas pressure, initial C 2H 5Cl concentration and dose range were equal in both cases. An elaborated model allow us to obtain quantitatively similar results as the experiments, but the degree of C 2H 5Cl decomposition for certain dose levels is significantly higher in experimental data. It is quite probable that some important processes have not been included to the theoretical model. 相似文献
6.
Rate constants for the tunneling reaction (HD + D → h + D 2) in solid HD increase steeply with increasing temperature above 5 K, while they are almost constant below 4.2 K. The apparent activation energy for the tunneling reaction above 5 K is 95 K, which is consistent with the energy (91–112 K) for vacancy formation in solid hydrogen. The results above 5 K were explained by the model that the tunneling reaction was accelerated by a local motion of hydrogen molecules and hydrogen atoms. The model of the tunneling reaction assisted by the local motion of the reactans and products was applied to the temperature dependence of the proton-transfer tunneling reaction (C 6H 6− + C 2H 5OH → C 6H 7 + C 2H 5O −) in solid ethanol, the tunneling elimination of H 2 molecule of H 2 molecule ((CH 3) 2 CHCH(CH 3) 2+ → (CH 3) 2 C = C(CH 3) 2+ + H 2) in solid 2,3-dimethylbutane, and the selective tunneling reaction of H atoms in solid neo-C 5H 12-alkane mixtures. 相似文献
7.
Volume changes on mixing of ternary liquid mixtures of N,N-dimethylformamide and diethyl ketone with 1-alkanols have been measured as a function of composition at 303.15 K. The alkanols include 1-propanol, 1-butanol, 1-pentanol and 1-hexanol. The measured VE values are negative in the mixtures of N,N-dimethylformamide, diethyl ketone and 1-propanol, or 1-butanol. The VE data exhibits an inversion in sign in the mixture containing 1-pentanol and positive excess volumes are observed in the mixture containing 1-hexanol. The measured data are compared with predicted values based upon empirical relations. The excess volume for the binary mixture of N,N-dimethylformamide with diethyl ketone has been measured over the entire range of composition at 303.15 K. The VE values are negative for the binary mixture. 相似文献
8.
Intermolecular potentials have been obtained from high-energy total cross sections for several alkali metal systems: CS + He, Ne, Ar, CH 3NO 2; K + CH 4, C(CH 3) 4, C 6H 6, c-C 6H 12, CH 3I, CCl 4, SF 6, N 2. For the CS-rare gas cases and K + N 2 only the repulsive part was determined. For the rest both attractive and repulsive parts were seen. 相似文献
9.
The reaction of CH 3C(CH 2Cl) 3 and NaSb(C 6H 5) 2 in liquid ammonia leads to Sb 2(C 6H 5) 4 (I). Using CH 3C(CH 2Br) 3 instead of CH 3C(CH 2Cl) 3 results in the formation of I and CH 3C[CH 2Sb(C 6H 5) 2] 3 (II). Treatment of II with gaseous HCl in dry CH 2Cl 2 yields CH 3C(CH 2SbCl 2) 3 (III) under elimination of benzene. The reduction of III with Na in THF gives the first all- cis-organocyclotristibane (Sb 3-nortricyclane) CH 3C(CH 2Sb) 3 (IV) which forms the new CH 3C(CH 2Sb) 3M(CO) 5 complexes (Va---Vc) with M(CO) 5THF (M = Cr, Mo, W). 相似文献
10.
(C 5H 5) 2Lu(μ-Cl 2)Na(dme) 2 reacts with LiSi(CH 3) 3 in dimethoxyethane with formation of [Li(dme) 3][(C 5H 5) 2Lu(Si(CH 3) 3) 2]. The crystal structure study shows the compound to consist of discrete ions [Li(dme) 3] + and [(C 5H 5) 2Lu(Si(CH 3) 3) 2] −. The compound crystallizes in the space group P2/ n with a 14.497(5) b 9.041(2), c 14.672(6) Å, β 103.85(3)° and V 1867(2) Å 3. The crystal and molecular structure was refined to R = 0.0473 for 2491 observed reflections with Fo 3σ( Fo). 相似文献
11.
The infrared spectra of phosphinic acid R 2POOH dimers (R=CH 3, CH 2Cl, C 6H 5) have been studied in CCl 4 and CH 2Cl 2 solutions ( T=300 K). The infrared spectra of deuterated R 2POOD dimers (R=CH 3, CH 2Cl) were also studied in the gas phase ( T=400–550 K) and solid state ( T=100–300 K). They are compared with previously studied spectra of the light (non-deuterated) dimers in the gas phase, in the solid state and in low-temperature argon matrices ( T=12–30 K) in the 4000–400 cm −1 spectral region. It is found that the strong and broad ν(OH) dimer bands have similar shapes, nearly equal values of bandwidth and low-frequency shift, and possess the Hadzi ABC structure irrespective of the type of acid, significant differences of dimerization enthalpies, influence of solvent, the type of H-bonded complexes (cyclic dimers in the gas phase, in solutions, and in inert matrices, and infinite chains in the solid state), and temperature in the range 12–600 K. Isotopic ratio of the first moments of light and deuterated acid bands has been measured. Analysis of the ν(OH/OD) band of hydrogen bonded dimers of phosphinic acids shows that the interaction between the two intermolecular bonds O–HOP in a cyclic complex plays virtually no role in the mechanism of the ν(OH/OD) band formation; the shape of ν(OH/OD) band is controlled mainly by the POOH(D)O fragment; and the band shape of strong hydrogen bonded complexes is formed by a number of vibrational transitions from the ground state to different combination levels in the region 3500–1500 cm −1. 相似文献
12.
Densities of {(1− x)CH 3(CH 2) n−1OH + xCH 3CN} for n=1, 2, 3 or 4 have been determined as a function of composition at 288.15, 293.15, 298.15 and 303.15 K at atmospheric pressure using a vibrating-tube densimeter (Anton Paar DMA 4500, resolution 1×10 −5 g cm −3). Excess molar volumes were calculated. The VmE values were negative for acetonitrile–methanol mixtures and sigmoid for acetonitrile–alkanols (C 2–C 4) mixtures over the complete mole fraction range. VmE values increase in a positive direction with increase in chain length of the alkanols and with the temperature. The Extended Real Associated Solution Model (ERAS-Model) calculations allowing for self-association for the alkanols and complex formation between acetonitrile and alkanols have been used to correlate experimental data. The model is able to reproduce the asymmetrical VmE behavior of the studied systems, although agreement between theoretical and experimental values is less satisfactory for some concentration ranges. 相似文献
13.
When heated under reflux in CH 2Cl 2 solution with [Os(CO) 3Cl 2] 2, two nido-[B 9H 12] − units edge-fuse to form anti-[B 18H 21] −. 相似文献
14.
Soluble homogeneous organophosphorus—nickel complexes have been used to detoxify polychlorinated biphenyls (PCBs) by catalyzed hydrodechlorination using NaBH 2(OCH 2CH 2OCH 3) 2 as the hydrogen source. The reactions appear to proceed by NiL 3 oxidative addition into C---Cl bonds followed by hydrogenolysis of the metal---carbon bond. In model experiments with decachlorobiphenyl, the cone angle of the organophosphorus ligand L was shown to be a key factor controlling the magnitude and position of chlorine displacement. Hence, ligands leading to para displacement (e.g. ( o-MeC 6H 4O) 3P), meta—para displacement (e.g. (EtO) 3P and (PhO) 3P), and ortho—meta—para displacement (e.g. Me 3P and Et 3P) were found. Significantly, the highly toxic, coplanar dioxin precursor 3,3′,4,4′-tetrachlorobiphenyl, a meta—para chlorine-substituted congener, was dechlorinated quantitatively with the Et 3P catalyst system. Evidence for the presence of organonickel intermediates in the reaction mixtures was obtained by mass spectroscopic and X-ray diffraction studies. Of particular interest is the isolation of square planar complexes p-C 6Cl 5C 6Cl 4Ni(PEt 3) 2Cl from the reaction of decachlorobiphenyl with NaBH 2(OCH 2CH 2OCH 3) 2—(Et 3P) 2NiCl 2 as the catalyst precursor and m-C 6Cl 5C 6Cl 4Ni(PEt 3) 2Cl from decachlorobiphenyl—Ni(1,5-C 8H 12) 2—PEt 3 at room temperature. All are oxidative addition intermediates and precursors for decachlorobiphenyl hydrodechlorination. 相似文献
15.
A series of novel heterobimetallic crown ether-like polyoxadiphosphaplatinaferrocenophanes cis-[1,1′-Fc(CH 2O(CH 2CH 2O) nCH 2CH 2PPh 2) 2]PtCl 2 ( n=1–3) (4a–c) was synthesized in good yield by cyclization of the bis(phosphine) ligands 1,1′-Fc(CH 2O(CH 2CH 2O) nCH 2CH 2PPh 2) 2 ( n=1–3) (3a–c) and (PhCN) 2PtCl 2 under high dilution conditions in CH 2Cl 2. The bisphosphines 3a–c are obtained by reaction of the corresponding diols 1,1′-Fc(CH 2O(CH 2CH 2O) nCH 2CH 2OH) 2 ( n=1–3) (1a–c) with: (i) CH 3SO 2Cl in CH 2Cl 2 and (ii) LiPPh 2 in THF. Although the X-ray crystal structure of 4a shows that the cavity is large enough for the encapsulation of small metal cations, inclusion experiments of 4a–c with Group 1 cations, and Mg 2+, or NH 4+ in solution applying NMR titration and cyclovoltammetric methods reveal no evidence for the formation of host–guest complexes for 4a,b. In the case of 4c only the addition of Na + or K + leads to an insignificant effect. 相似文献
16.
The neutral nitrogen-bidentate ligand, diphenylbis(3,5-dimethylpyrazol-1-yl)methane, Ph 2CPz′ 2, can readily be obtained by the reaction of Ph 2CCl 2 with excess HPz′ in a mixed-solvent system of toluene and triethylamine. It reacts with [Mo(CO) 6] in 1,2-dimethoxyethane to give the η 2-arene complex, [Mo(Ph 2CPz′ 2)(CO) 3] (1). This η 2-ligation appears to stabilize the coordination of Ph 2CPz′ 2 in forming [Mo(Ph 2CPz′ 2)(CO) 2(N 2C 6H 4NO 2- p)][BPh 4] (2) and [Mo(Ph 2CPz′ 2)(CO) 2(N 2Ph)] [BF 4] (3) from the reaction of 1 with the appropriate diazonium salt but the stabilization seems not strong enough when [Mo{P(OMe) 3} 3(CO) 3] is formed from the reaction of 1 with P(OMe) 3. The solid-state structures of 1 and 3 have been determined by X-ray crystallography: 1-CH 2Cl 2, monoclinic, P2 1/ n, a = 11.814(3), b = 11.7929(12), c = 19.46 0(6) Å, β = 95.605(24)°, V = 2698.2(11) Å 3, Z = 4, Dcalc = 1.530 g/cm 3 , R = 0.044, Rw = 0.036 based on 3218 reflections with I > 2σ( I); 2 (3)-1/2 hexane-1/2 CH 3OH-1/2 H 2O-1 CH 2Cl 2, monoclinic, C2/ c, a = 41.766(10), b = 20.518(4), c = 16.784(3) Å, β = 101.871(18)°, V = 14076(5) Å 3, Z = 8, Dcalc = 1.457 g/cm 3, R = 0.064, Rw = 0.059 based on 5865 reflections with I > 2σ( I). Two independent cations were found in the asymmetric unit of the crystals of 3. The average distance between the Mo and the two η 2-ligated carbon atoms is 2.574 Å in 1 and 2.581 and 2.608 Å in 3. The unfavourable disposition of the η 2-phenyl group with respect to the metal centre in 3 and the rigidity of the η 2-arene ligation excludes the possibility of any appreciable agostic C---H → Mo interaction. 相似文献
17.
We show that thermal desorption kinetics clearly resolve adsorbates bound in different sites on single walled carbon nanotube bundles. The molecules n-C 9H 20 and CCl 4 were compared and it was found that the nanotube internal sites exhibited the highest desorption temperature, whereas external groove sites exhibited the next highest desorption temperature for both molecules. When n-C 9H 20 and CCl 4 coadsorb, the more strongly bound n-C 9H 20 quantitatively displaces CCl 4 from internal sites to groove sites. Molecular shape governs the capacity of the different sites for the two molecules. 相似文献
18.
New ester salts [R 3NH] +[F 5SC(SO 2F)C(O)OR′] − where RH, CH 3CH 2 and R′CH 3,(CH 3) 2CH have been prepared from corresponding esters and amines. The sodiumsalt Na[F 5SC(SO 2F)C(O)OCH(CH 3) 2] was used to prepare the following -substitutedderivatives: SF 5CX(SO 2F)C(O)OCH(CH 3) 2, XBr, Cl. The crystal structure of[(C 2H 5) 3NH] +[F 5SC(SO 2F)C(O)OCH 3] − was determined and is monoclinic: P2 1/ n; a=8.758(2) Å, b=9.645(2) Å and c=19.167(4) Å; β=97.92(3)°; V=1603.6 Å 3; Z=4. 相似文献
19.
Reaction rate coefficients and product ion distributions have been measured for the reaction of Ne + with H 2, N 2, CO, CO 2, N 2O, CH 4, O 2, NO, NH 3, SO 2, CH 3Cl, COS, H 2O and C 2H 4 at 300 K using a selected ion flow tube (SIFT) apparatus. In most cases the major reaction channel involves dissociative ionization while for N 2, CO +, H 2O, CH 4 and CH 3Cl these reactions proceed mainly or exclusively by simple charge transfer. For H 2 the process is exclusively hydrogen atom abstraction. The measured rate coefficients are compared with the values given by the Langevin and average-dipole orientation theories of ion—molecule collisions. In general the reaction probability (ratio of measured rate to the Langevin or ADO rate) is greater for the dissociative ionizaton reactions, although H 2O is an exception with quite fast simple charge transfer. 相似文献
20.
The crystal structures of propionaldehyde complex ( RS, SR)-(η 5-C 5H 5)Re(NO)(PPh 3)(η 2-O=CHCH 2CH 3)] + PF 6− (1b + PF 6s−; monoclinic, P2 1/ c (No. 14), a = 10.166 (1) Å, b = 18.316(1) Å, c = 14.872(2) Å, β = 100.51(1)°, Z = 4) and butyraldehyde complex ( RS, SR)-[(η 5-C 5H 5)Re(NO)(PPh 3)(η 2-O=CHCH 2CH 2CH 3)] + PF 6− (1c +PF 6−; monoclinic, P2 1/ a (No. 14), a = 14.851(1) Å, b = 18.623(3) Å, c = 10.026(2) Å, β = 102.95(1)°, Z = 4) have been determined at 22°C and −125°C, respectively. These exhibit C
O bond lengths (1.35(1), 1.338(5) Å) that are intermediate between those of propionaldehyde (1.209(4) Å) and 1-propanol (1.41 Å). Other geometric features are analyzed. Reaction of [(η 5-C 5H 5)Re(NO)(PPh 3)(ClCH 2Cl)] + BF 4− and pivalaldehyde gives [(η 5-C 5H 5)Re(NO)(PPh 3)(η 2-O=CHC(CH 3) 3)] +BF 4− (81%), the spectroscopic properties of which establish a π C
O binding mode. 相似文献
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