Cyclohexane, calculated benzene

Figure 4-23. Calculated and experimental selectivities and distribution coefficients for the type-I ternaries in the 2,2,4-trimethyl pentane-cyclohexane-furfural-benzene system.

Calculated and Experimental Liquid-Liquid Equilibria for a Quarternary System at 25 C 2,2,4-trimethylpentane(1)-furfural(2)-cyclohexane(3)-benzene(4)... 

Calculate, using the data of Fig. III-9a and Eq. III-53, the surface tension versus mole fraction plot for mixtures of cyclohexane and benzene. 

The entropy factor should also be considered since cyclization results in a more ordered structure. The C5 cyclization of n-hexane involves an entropy decrease of about 15-17 entropy units (e.u.). The corresponding values for cyclohexane and benzene formation are about 25 and 38-45 e.u., respectively. These values are comparable with calculated values of adsorption entropy (29). Thus, adsorption of a molecule to be cyclized may supply a considerable part of the entropy change in other words, adsorption should take place in a geometry favorable for cyclization. This is one of the main roles of the catalyst. 

The calculated amounts of the catalyst, reactant and solvent (if needed) are then placed in the hydrogenation vessel. Utmost care must be exercised in loading the hydrogenation container with catalysts which are pyrophoric, especially when highly volatile and flammable solvents like ether, methanol, ethanol, cyclohexane or benzene are used. The solution should be added to the catalyst in the container. If the catalyst must be added to the solution this should be done under a blanket of an inert gas to prevent potential ignition. 

A quantitative study of the RISC quantum yield was carried out with 55 [37]. This study involved UV irradiation of 55 in benzene or cyclohexane solution to produce the 7, state and subsequent photolysis by a second laser tuned to the T-T absorption band. The second pulse was accompanied by depletion (bleaching) of the T-T absorption and 5, — S0 fluorescence [the fluorescence was detected and quantified by an optical multichannel analyzer (OMA)]. The quantum yield of RISC, d>RISC, was calculated using Aberchrome 540, a reversible fulgide, as a two-laser actinometer. The values for benzene solvents, respectively. This compares with 0.19 found for 55 in ethanol solvent [36]. 

Figure 9.2 Calculated total conversion profile of cyclohexane to benzene in a porous shell-and-tube Vycor glass membrane reactor with membrane thickness as a parameter [ltohetal.,1985]...

Pyrazine forms an azeotrope with water [60% pyrazine-40% water, b.p. 95.5° (uncorr.) (760mmHg) /ip 1.4510] (578). A method of assay for pyrazine and some common impurities has been developed (579). The dipole moment (Debye units) of pyrazine has been determined in dioxane, cyclohexane, and benzene as zero (580, cf. 581) and it has also been calculated as zero (133, 582). The e.s.r. spectrum (583) and the polarized single-crystal absorption spectra of pyrazine (and tetramethylpyrazine) (584) have been recorded. The photoelectron spectra of pyrazine and tetramethylpyrazine have been determined and suggest a different behavior towards electrophilic attack in the two cases (585). 

The calculations were conducted for aqueous solutions of alcohols (methanol, ethanol, propanols, butanols, and tert-pentanol) and hydrocarbons (normal saturated aliphatic hydrocarbon from propane through dodecane, isobutane, cyclopentane, cyclohexane, cycloheptane, benzene, toluene). 

Sanni and Hutchison (1973) presented data on the binary Fick dilfusivity for the systems benzene-chloroform, cyclohexane-carbon tetrachloride, cyclohexane-toluene, benzene-cyclohexane, benzene-toluene, and diethyl ether-chloroform. Calculate the thermodynamic factor F for these systems using parameters from Gmehling and Onken (1977ff). Hence, estimate the Maxwell-Stefan diffusion coefficients and test the applicability of the Vignes model. 

Q.9.19 Using the bond energies given below calculate the heat of formation of gaseous hexane, cyclohexane and benzene. Compare your answers with the thermodynamic heats of formation given in Table 10.1. Explain any discrepancies. 

Theoretical calculations support a low-energy oxidative addition mechanism [26c], Reaction of the unsolvated cationic complex Cp Ir(PMe3)(CH3) with pentane, cyclohexane or benzene in the gas phase also gives Cp Ir(PMe3)(R) as the product. However, a mechanistic investigation of this process by electrospray tandem spectrometry has demonstrated that neither the oxidative addition-elimination mechanism nor the concerted a-bond metathesis mechanism is operative. Instead, the authors proposed a dissociative elimination-addition mechanism which proceeds through a series of 16-electron Ir(III) intermediates [26d]. 

Examine with the help of the regular solution theory, UNIFAC and modified UNIFAC if the binary systems benzene-cyclohexane and benzene-n-hexane show an azeotropic point at 80 C. In case of the regular solution theory, calculate the solubility parameter from the saturated liquid density and the heat of vaporization using Eq. (5.70). All required data are given in Appendices A, H, and 1. 

Problem 6.2. Calculate AH° from the bond energies in Table 1.1 (Chapter 1) for the conversion of cyclohexane to benzene and hydrogen as shown in Equation 6.4 at 25°C and 1 atm. From this, with AS as -100 JK moF and Equation 4.3 estimate AG° under the same conditions. In order for the reaction to proceed as written (without a catalyst) to what temperature must it be heated ... 

Table 5 also summarizes the selectivities for the separation of hexane/benzene, cyclohexane/benzene, and hexane/hexene mixtures at T=298.15 K, which were calculated from the y values for the ILs under study and collected from literature. As presented in table 5, the trend in Sy values depends on the number of carbon atoms in the alkyl groups attached to the cation, most of the ILs with shorter alkyl chain have higher Sy values while those with longer alkyl chain have smaller Sy" values, e.g., [OMIM][BF4], 9 carbon atoms, Sy" (i = hexane,) = benzene) =10.4, Sy i = cyclohexane, j = benzene) = 6.8 [BMIM][BF4], 5 carbon atoms, Sy i = hexane, j = benzene) = 37.3, Sy i = cyclohexane, j = benzene) = 19.7 ... 

For adsorption on Spheron 6 from benzene-cyclohexane solutions, the plot of N N2/noAN2 versus N2 (cyclohexane being component 2) has a slope of 2.3 and an intercept of 0.4. (a) Calculate K. (b) Taking the area per molecule to be 40 A, calculate the specific surface area of the spheron 6. (c) Plot the isotherm of composition change. Note Assume that is in millimoles per gram. 

Now calculate the molecular weight of the substance precisely as described on p. 442. The weight of the solvent employed may be calculated from the following densities methanol, 0 810 rectified spirit, 0-807 acetone, 0 797 ethyl acetate, 0 905 chloroform, 1 504 carbon tetrachloride, 1 582 benzene, 0 880 toluene, 0-871 cyclohexane, 0-724 i, 2-dichloroethane, 1 252. 

For a detailed discussion of the calculation of activities (and excess Gibbs free energies) from freezing point measurements, see R. L. Snow. J. B. Ott. J. R. Goates. K. N. Marsh, S. O Shea, and R. N. Stokes. "(Solid + Liquid) and (Vapor + Liquid) Phase Equilibria and Excess Enthalpies for (Benzene + //-Tetradecane), (Benzene + //-Hexadecane). (Cyclohexane + //-Tetradecane), and (Cyclohexane +//-Hexadecane) at 293.15, 298.15, and... 

Fig. 38.—Plots of w/c against c for a series of polyisobutylene fractions M =38,000 to 720,000) in cyclohexane ( ) and in benzene (O), both at 30°C. The osmotic pressure tz is expressed in g./cm. and c in g./lOO cc. Curves have been calculated according to Eq. (13). (Krigbaum. )...

Fig. 143.—The intrinsic viscosity of a polyisobutylene fraction of high molecular weight plotted against temperature in four solvents cyclohexane, diisobutylene (DIB), toluene and benzene. The lines shown have been calculated according to theory. (Fox and Flory. )...

Calculate the standard heat of reaction for the following reaction the hydrogenation of benzene to cyclohexane. 

Hm for steam + n-heptane calculated by the above method is shown by the dashed lines in figure 6. Considering the simplicity of the model and the fact that no adjustable parameters have been used, agreement with experiment is remarkable. For mixtures of steam + n-hexane, benzene and cyclohexane agreement with experiment is much the same. At low densities the model reproduces the curvature of the lines through the results better than the virial equation of state. The method fails to fully reproduce the downward turn of the experimental curves at pressures near saturation, but does marginally better in this region than the P-R equation with k. = -0.3. At supercritical temperatures the model seems to... 

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