Benzene Cyclohexane Research Articles

Vapor pressure isotope effects in the benzene (B)–cyclohexane (C) system from 5 to 80 °C. I. The pure liquids B-d,B-d1,o r t h o-,m e t a-, and p a r a-B-d2, B-d6,C-d, and C-d12. II. Excess free energies and isotope effects on excess free energies in the solutions B-h6/B-d6, C-h12/C-d12, B-h6/C-h12, B-d6/C-h12, and B-h6/C-d12

High precision measurements of the vapor pressure differences between some deuterated benzenes B-dx (x=1, para-2, and 6) and protio benzene B-d0; between para- and ortho-, and para- and meta-dideuterobenzene; and between perdeuterocyclohexane C-d12 and protiocyclohexane C-d0 were made from near the freezing point to the normal boiling point. The data are best represented as the logarithmic ratios ln R (d6) =ln (Pd0/Pd6) =1226.5/T2−12.178/T, ln R (para/ortho) =ln (Ppara-d2/Portho-d2) =2.6/T2, and ln R (para/meta) =ln (Ppara-d2/Pmeta-d2) =−2.0/T2, together with the deviations from the law of the mean Δ (d1) =6−[ln R (d6)/lnR (d1)]=0.177−3.6×10−4t and Δ (d2-para=3−[ln R (d6)/ln R (d2-para)]=0.028 +1.0×10−4t. The isotope effects are inverse and display significant deviations from the law of the mean. The cyclohexane results are given by ln R (C-d12) =−2188.4/T2−18.587/T. New measurements of the vapor pressures of benzene–cyclohexane solutions are also reported between 5 and 80 °C. The data are in good agreement with the best earlier work. Excess free energies of the equimolar solutions B-h6/B-d6 and C-h12/C-d12 have been measured between 20 and 80 °C. Suitable fits to the data yield the following results (30 °C); Gex(B-h/B-d), Gex(C-h/C-d); Hex(B-h/B-d), Hex(C-h/C-d); 0.57,1.04;1.1,3.1 J/mole. For the isotope effects on the excess properties of benzene–cyclohexane solutions differential pressure measurements were taken as a function of temperature (20–80 °C) and concentration (XC=0.10, 0.25,0.50,0.70,0.75,0.85,0.90). The isotope effects on the excess properties at 25 °C are as follows: Gex(B-d/C-h) −Gex(B-h/C-h), Gex(B-h/C-d)−Gex(B-h/C-h); Hex(-d/C-h)−Hex(B-h/C-h), Hex(B-h/C-d) −Hex(B-h/C-h); 7.5,2.6;32,0 J/mole at Xc=0.5, but equations are presented so that the effects can be calculated at any concentration or temperature. The results are briefly discussed in the context of the theory of isotope effects in condensed phase systems.

Vapor pressure isotope effects in benzene–cyclohexane systems. III. Theoretical analysis

The data of Jakli, Tzias, and Van Hook (preceeding paper) on vapor pressure isotope effects in the series of deuterobenzenes, solutions of isotopic isomers of benzene and cyclohexane, and mixtures of benzene and cyclohexane are analyzed in terms of the theory of isotope effects in condensed phase systems using a cell model in the quasiharmonic approximation. The single largest contribution to the VPIE’s arises from the shift in the CH stretching force constant on condensation but other effects, including external internal coupling and the volume dependence of condensed phase internal frequencies, are also important. Molar volume isotope effects are demonstrated to be of critical importance in arriving at an understanding of the excess thermodynamic properties of solution.

Separation of Copper(II), Nickel(II), Palladium(II), and Cobalt(II) Chelates with 4-S-Benzyl-l-p-Cl-phenyl-5-phenyl-2,4-isodithiobiuret (BPPTB) from Their Binary Mixture by Adsorption Thin-Layer Chromatography

Abstract In the present work a suitable solvent system for the separation of Cu(II), Ni(II), Co(II), and Pd(II) as their chelates with 4-S-benzyl-1-p-Cl-phenyl-5-phenyl-2,4-isodithiobiuret (BPPTB) from their binary mixtures has been suggested. The most applicable solvent system has been found to be benzene-cyclohexane (3: 1). The best separation is achieved within 15 min. RF values of Ni-(BPPTB)2 and Co-(BPPTB)2 decrease with time. The substitution of benzene in a benzene–cyclohexane (1:1) solvent mixture by toluene decreases the RF value of metal chelates. Cu-(BPPTB)2 and Pd-(BPPTB)2 chelates do not migrate even with an increase in temperature. The RF value of Ni(BPPTB)2 chelate increases with temperature, whereas the RF value of Co-(BPPTB)2 remains practically constant.

Vapour—liquid equilibria of the systems acetone—benzene, benzene—cyclohexane and acetone—cyclohexane at 25°C

Vapour—liquid equilibrium data for the binary systems acetone—benzene, benzene—cyclohexane and acetone—cyclohexane have been determined experimentally at 25°C. The reduction producers based on P - x - y as well as on P - x isothermal data sets, which incorporate usual thermodynamically consistent models expressing the dependence of activity coefficients of liquid composition, have been examined for representing the reported results. Nonideal behaviour of the both phases has been taken into account. Thermodynamic consistency of the data has been shown by comparing of the experimentally obtained vapour compositions with those calculated from P - x data using the best of the examined models for activity coefficients.

１，４‐シクロヘキサジエン

1, 4-Cyclohexadiene (1, 4-CHD) is easily prepared by the Birch reduction using an alkali metal and a proton source in liquid ammonia or by the electrolytic reduction, and the 1, 4-CHD can be isomerized to 1, 3-CHD and disproportionated to benzene and cyclohexene or cyclohexane. While the addition reaction of one double bond in the 1, 4-CHD occurs easily, the reactivity of the other double bond is lowered. As the disproportionation and the hydrogenation are carried out using the same catalyst, it seems reasonable that the reaction of the 1, 4-CHD with the catalyst forms once a π-complex, the 1, 4-CHD moiety of the π-complex is eliminated as benzene by heating, the remaining catalyst moiety having two hydrogen atoms of the complex reacts with the other 1, 4-CHD molecule to form the hydrogenated π-complex, which gives cyclohexene. The 1, 4-CHD forms the 1, 4-, 1, 3-CHD of phenyl-π- complexes depending upon various kinds of metals of the catalyst, and the mass spectra of the 1, 3-π- complex indicates the presence a metastable ion during the cource from the molecular ion to the dehydrogenated phenyl-π-complex ion. The polymerizability of 1, 4-CHD monomer is low and poly-1, 3-CHD-, polymer of a low molecular weight is formed after the isomerization to 1, 3-CHD in the polymerization. Its oxidation affords diepoxide and tetraol which can be used as polymers and modifiers, and its reaction with metal cyanide and phosgene affords tetracyanoquinodimethane which can be also used as conductive polymers and super conduction materials.

Quenching of benzene fluorescence in pulsed proton irradiation: Dependence on proton energy

Dilute solutions of benzene in cyclohexane were irradiated with subnanosecond pulses of protons from a 2 MV accelerator. Changes in the time resolved emission at 285 nm were studied as a function of proton energy. The initial rate of fluorescence decay is energy dependent and always greater than that observed with ultraviolet radiation. As time after irradiation increases, the decay rate approaches the uv value. A model based upon quenching by transient species in the proton track is used to analyze the data. The analysis suggests that the energy dependence of the initial decay rate results from the effect of proton stopping power on the initial quencher concentration.

Quenching of benzene fluorescence in pulsed proton irradiation

The luminescence behavior of dilute solutions of benzene in cyclohexane is investigated for proton and ultraviolet excitation. Benzene fluorescence from proton excitation does not show the delayed component that has been reported for numerous aromatic solvents. Instead there is an initial rapid decay attributed to dynamic quenching followed by a slower decay approaching that observed for ultraviolet excitation. The initial quenching is shown to be consistent with intratrack quenching by transient species.

Retention of hydrocarbons on gas chromatographic sorbents containing an organo-clay

The equation describing retention on a combined sorbent containing a solid adsorbent and a stationary liquid phase (SLP) have been obtained on the basis of a theory of retention developed earlier. Experimental methods have been proposed for estimating the relative roles of dissolution and adsorption for combined sorbents based on organo—clays. The distribution coefficients of C 6C 10 hydrocarbons between a carrier gas and an SLP layer, SLPL surfaces, a solid support and organo-vermiculite, and SLP—solid support and SLP—organo—vermiculite interfaces have been determined. The selectivity of adsorption in the separation of the pairs benzene—cyclohexane and m-xylene— p-xylene has been studied for sorbents containing pure and impregnated organo—vermiculites. It has been shown that the selectivtiy depends on the polarity of the SLP.

The liquid—liquid equilibrium for activity coefficient determination

A method based on liquid—liquid equilibrium is proposed for the determination of activity coefficients. The reliability of this procedure is tested on the systems cyclohexane—benzene, cyclohexane—toluene, n-hexane—benzene, n-heptane—toluene.

Optical properties of a guest molecule in a discrete lattice

The optical properties of a simple model system consisting of an anisotropic guest molecule situated on a lattice site of a cubic lattice, the other sites being occupied by isotropic solvent molecules, are found. The results are compared to those found by a continuum (Onsager) approximation. It is found that some quantities, such as the dependence of the energy shift on the solvent dielectric constant εs, are qualitatively little affected by the discrete lattice structure, while others, such as radiative lifetimes and scattering cross sections, have a qualitatively different behavior for large εs. The Rayleigh ratio Ranis describing the anisotropic contribution to light scattering is found to contain a factor [(εs+2)/3]4 (in addition to another correction) in contrast to the usually assumed [(εs+2)/3]2 factor. The experimental ratio of the ratio Ranis (solution)/Ranis (gas) for CS2 and benzene in cyclohexane is satisfactorily reproduced by the present treatment while the continuum approximation gives a result about 20% too high. Some special optical properties arising from the anomalous dispersion of the energy bands of a simple cubic lattice are discussed.

Photolysis of benzene in cyclohexane at 2537 Ang

Photolysis of benzene in cyclohexane at 2537 Ang

A study of permeation of organic solvents through polymeric membranes based on polymeric alloys of polyphosphonates and acetyl cellulose. II. Separation of benzene, cyclohexene, and cyclohexane

Membranes prepared from polymeric alloys of polyphosphonates and acetyl cellulose are highly permeable to benzene and the cyclohexene, but practically impermeable to the aliphatic hydrocarbons cyclohexane and decalin. Pervaporation and osmotic distillation techniques were used in order to achieve separation of the benzene–cyclohexane mixtures. The flux of the permeate increases sharply with increasing temperature, concentration of benzene in the feed solution, and fraction of polyphosphonate in the membrane. The increase of permeate flux is accompanied by a slight decrease of the separation factors. The permeation characteristics of the membranes were compared with those predicted from the results of sorption experiments. The agreement between the observed and the predicted fluxes and separation factors indicates that the permeation mechanism can be described in terms of molecular diffusion. The high selectivity of the membranes makes possible the development of a novel “osmotic distillation” technique. Such a technique, which combines osmotic permeation of organic liquids with conventional distillation, may be advantageous in the separations of azeotropic mixtures.

Distillation at near terminal compositions: wetting effects at atmospheric and reduced pressures

Contact angles are reported using n-propanol—water, ethanol—water and cyclohexane—benzene mixtures at concentrations near their terminal compositions, measured under distillation conditions at atmospheric and reduced pressures. A literature survey shows that efficiencies of columns incorporating film contacting devices often decrease very significantly in the low composition range. By comparing the wetting data obtained for the system n-propanol—water with reported performance data using a disc column it is suggested that this behaviour is caused by wetting changes occurring in this region.

The yield of solvent excited states in the radiolysis of cyclohexane solutions

It is confirmed by pulse radiolysis that emitting solvent excited states are produced in the radiolysis of n-hexane, methylcyclohexane and cyclohexane. The emission is quenched by benzene and benzene emission appears. Applying stern - volmer kinetics to emissions from solvent, benzene and toluene in cyclohexane a very high energy transfer rate constant, viz., k = 2.8 × 10 11M −1 sec −1 is obtained. The yield of the excited state of cyclohexane is not greater than 0.3, and it is concluded that the major part of the excited states of other aromatics produced in cyclohexane solutions comes from ion neutralisation.

The effect of roughness on the values of contact angles of binary systems measured at atmospheric pressure and ambient temperature on poly(tetrafluoroethylene) surfaces

AbstractContact angles are reported for the systems ethanol–water, n‐propanol–water, and benzene–cyclohexane measured at atmospheric pressure and 25.0°C, in equilibrium with their vapors, on poly(tetrafluoroethylene) surfaces of known roughness. Comparison of the data with those reported by other workers has shown that the discordancy in values can be attributed solely to the various preparation techniques producing surfaces of differing roughnesses.

Studies in Solubility Parameter Theory for Mixed Solvent Systems

Data are presented for the saturation solubility and partial molal volume of iodine in a mixed benzene–cyclohexane solvent and for the saturation solubility of stannic iodide in the same solvent mixture. A successful interpretation of these data in terms of solubility parameter theory is possible if we define an effective volume fraction term. This term reflects the immediate solvent environment of the solute molecule with the preferential solvation of the solute by one of the solvent molecules. Data for iodine in a mixed carbon tetrachloride–benzene solvent mixture and for iodine in a carbon tetrachloride–perfluoroheptane mixture are also interpreted in terms of the proposed theory.

Proton spin‐lattice relaxation study of polymer solutions

AbstractProton spin‐lattice relaxation times of solvent molecules were measured on ternary mixtures of a polymer and two solvents by the adiabatic rapid‐passage method. The selective adsorption of a good solvent was verified by this experimental technique for the systems benzene—cyclohexane—polystyrene(PS), benzene—carbon tetrachloride—poly(methyl methacrylate)(PMMA), and chloroform—carbon tetrachloride—PMMA. The number of molecules of adsorbed benzene per monomeric unit of PS was estimated to be about four, which is almost identical with that determined previously by thermodynamic measurements. The number of molecules of benzene and chloroform adsorbed on PMMA were also determined to be about five and four, respectively. It was found that the interaction between chloroform and PMMA has the greatest effect on the molecular motion of the solvent, whereas the benzene—PS interaction is weak.

Temperature and solvent effects on the fluorescence of some simple aromatic molecules

The fluorescence yields and lifetimes of α-methylnaphthalene, o-xylene and tetralin in ethanol and methylcyclohexane, toluene in methylcyclohexane, benzene in cyclohexane, methylcyclohexane and ethanol have been measured as a function of temperature, and also for benzene in methanol and acetonitrile at room temperature. In every case, the measured fluorescence yield and lifetime decrease with temperature and are dependent on the solvent used. Expressing the radiative lifetime, τr, as τr=τ°r/n2, where n is the refractive index of the medium, it has been found that τ°r is constant with temperature for α-methylnaphthalene, o-xylene, tetralin, and toluene. It decreases slightly with increasing temperature for benzene. In every compound the value for τ°r, at room temperature, is independent of the solvent used. Possible reasons for the variation of the fluorescence yields with solvent and temperature are discussed. In benzene, solvent perturbations can increase non-radiative disappearance of the S1 state.

The pulsed laser photolysis of benzene in cyclohexane

It is shown that the 265 nm pulsed laser photolysis and pulse radiolysis of dilute solutions of benzene give rise to two transitory absorption spectra with maxima at 490 nm and 320 nm. The spectrum with λ max = 490 nm is shown to be the excimer state of benzene 1B 1g and the spectrum at λ max = 320 nm is attributed to a biradical of benzene. It is shown that the biradical is formed by reaction of the ground state and triplet states of benzene giving rise to short lifetimes of the triplet state at high benzene concentration. The rate constant for this process is 1.8 × 10 7 sec −1 and the quantum yield for intersystem crossing. φ T for the benzene 1B 2u state is 0.39.

The stereochemistry of the oxidation products of anthracene with lead tetra-acetate in various solvents

The reactions of anthracene with lead tetra-acetate in benzene, benzene–pyridine, benzene–cyclohexane, and chloroform are shown to give cis- and trans-9,10-diacetoxy-9,10-dihydroanthracene [(1) and (2)]. In benzene containing increasing amounts of methanol these products are gradually replaced by cis- and trans-9,10-dimethoxy-9,10-dihydroanthracene [(3) and (4)] and cis- and trans-9-acetoxy-10-methoxy-9,10-dihydroanthracene [(5) and (6)], with a preference for the trans-isomers. The conclusion is drawn that in non-protic solvents the reaction involves an intermediate carbonium ion, thus giving equimolecular amounts of (1) and (2), whereas in the presence of methanol the methoxy-group is transferred by the lead atom. The second substituent group is introduced by an SN2 displacement.