Cyclohexane methylcyclohexane mixture

Figure 16.8 Conversion of cyclohexane in the dehydrogenation of cyclohexane-methylcyclohexane mixtures at 300 °C and 4 bars.

Itoh, N., Watanabe, S., Kawasoe, K., Sato, T., Tsuji, T. (2006). A membrane reactor for hydrogen storage and transport system using cyclohexane-methylcyclohexane mixtures. Desalination, 234, 261. 

Figure 16.1 Freezing points of cyclohexane and methylcyclohexane mixtures.

Dehydrogenation of cyclohexane, methylcyclohexane, and their mixtures using a palladium MR up to 300 °C and 4 bars were found to be simple reactions, which could be enhanced according to hydrogen removal. The conversions of cyclohexane and methylcyclohexane in the MR exceeded their equihbrium conversions as expected the former was always lower than the latter under the same conditions. Finally, the dehydrogenation of the mixtures of methylcyclohexane and cyclohexane with the MR was found to show almost the same results in the separate cases. 

Of alicyclic compounds, fluorination of cyclopentane and cyclohexane has been sufficiently investigated in the past. Cycloheptane on fluorination with cobalt trifluoride gives a mixture of highly fluorinated and perfluorinated cycloheptanes and methylcyclohexanes [/2] (equation 12). 

Class (3) reactions include proton-transfer reactions of solvent holes in cyclohexane and methylcyclohexane [71,74,75]. The corresponding rate constants are 10-30% of the fastest class (1) reactions. Class (4) reactions include proton-transfer reactions in trans-decalin and cis-trans decalin mixtures [77]. Proton transfer from the decalin hole to aliphatic alcohol results in the formation of a C-centered decalyl radical. The proton affinity of this radical is comparable to that of a single alcohol molecule. However, it is less than the proton affinity of an alcohol dimer. Consequently, a complex of the radical cation and alcohol monomer is relatively stable toward proton transfer when such a complex encounters a second alcohol molecule, the radical cation rapidly deprotonates. Metastable complexes with natural lifetimes between 24 nsec (2-propanol) and 90 nsec (tert-butanol) were observed in liquid cis- and tra 5-decalins at 25°C [77]. The rate of the complexation is one-half of that for class (1) reactions the overall decay rate is limited by slow proton transfer in the 1 1 complex. The rate constant of unimolecular decay is (5-10) x 10 sec for primary alcohols, bimolecular decay via proton transfer to the alcohol dimer prevails. Only for secondary and ternary alcohols is the equilibrium reached sufficiently slowly that it can be observed at 25 °C on a time scale of > 10 nsec. There is a striking similarity between the formation of alcohol complexes with the solvent holes (in decalins) and solvent anions (in sc CO2). 

The yield determined in a certain type of experiment usually strongly depends on the assumptions made about the formation mechanism. In the older literature, the excited molecules were often assumed to be produced solely in neutral excitations [127,139-143] and energy-transfer experiments with Stern-Volmer-type extrapolation (linear concentration dependence) were used to derive G(5 i). For instance, by sensitization of benzene fiuorescence, Baxendale and Mayer established G(5 i) = 0.3 for cyclohexane [141]. Later Busi [140] corrected this value to G(5 i) = 0.51 on the basis that in the transfer, in addition to the fiuorescing benzene state S, the S2 and S3 states also form and the 82- 81 and 83 81 conversion efficiencies are smaller than 1. Johnson and Lipsky [144] reported an efficiency factor of 0.26 0.02 per encounter for sensitization of benzene fluorescence via energy transfer from cyclohexane. Using this efficiency factor the corrected yield is G(5 i) = 1.15. Based on energy-transfer measurements Beck and Thomas estimated G(5 i) = 1 for cyclohexane [145]. Relatively small G(5 i) values were determined in energy-transfer experiments for some other alkanes as well -hexane 1.4, -heptane 1.1 [140], cyclopentane 0.07 [142] and 0.12 [140], cyclooctane 0.07 [142] and 1.46 [140], methylcyclohexane 0.95, cifi-decalin 0.26 [140], and cis/trans-decalin mixture 0.15 [142]. 

The oil that separates is extracted with ether, the extract dried over anhydrous sodium sulfate and then evaporated at reduced pressure. The residue is dissolved in boiling benzene (75 ml) treated with decolorizing charcoal, filtered, treated with boiling cyclohexane (275 milliliters) and cooled to give 22.3 grams of 2,3-dichloro-4-butyrylphenoxyacetic acid. After several recrystallizations from a mixture of benzene and cyclohexane, then from methyl cyclohexane, next from a mixture of acetic acid and water, and finally from methylcyclohexane, the product melts at 110° to 111°C (corr). 

Figure 3.3 Variation of retention (distribution coefficient) with the composition of the stationary phase in GLC at three different temperatures (indicated in the figure in °C). Stationary phase mixtures of squalane and dinonylphthalate (DNP). Solutes (a) n-octane, (b) cyclohexane, (c) methylcyclohexane and (d) tetrahydrofuran. Straight lines observe eqn.(3.14). Figure taken from ref. [304]. Reprinted with permission. 

The reaction of methylcyclohexane with an equimolar quantity of ethylene in the presence of di-t-butyl peroxide and hydrochloric acid resulted in ethylation both at the tertiary carbon atom and at secondary carbon atoms (Expt. 7). The methylethylcyclo-hexane which was obtained in 13% yield consisted (according to infrared (ir) comparison with authentic samples) chiefly of 1-methyl-1-ethylcyclohexane mixed with smaller amounts of l-methyl-cis-3-ethylcyclohexane and 1-methyl-cis- (and trans-)4-ethylcyclohexane, and other isomers. The compounds produced by the reaction of 2 mols of ethylene per mol of cyclohexane (7% yield) consisted of a mixture of methylbutylcyclohexanes and methyldiethylcyclohexanes. 

Organosilane hydrides are generally inert toward alkyl halides, while they exhibit potential reducing ability when mixed with a catalytic amount (5 mol %) of aluminum chloride. For instance, bromocy-clohexane is reduced to cyclohexane in 90% yield by treatment with Et3SiH/AlCl3 at 0-40 °C however, bromocycloheptane under similar conditions is converted to a 60 40 mixture of cycloheptane and methylcyclohexane in 65% combined yield. " ... 

Typical mixtures that can be separated by extractive distillation in processes similar to the one described above include cyclohexane and benzene, and toluene and methylcyclohexane, both using phenol as the solvent. In another process, isobutane and 1-butene are separated using furfural as the solvent. 

A feed mixture containing 50wt% n-heptane and 50wt% methyl cyclohexane (MCH) is to be separated by liquid-liquid extraction into one product containing 92.5 wt% methylcyclohexane and another containing 7.5 wt% methylcyclo-hexane. Aniline will be used as the solvent. 

Cycloheptane and cyclooetane at 200-250 C when hydrogenated over nickel undergo changes to methyl and dimethyl derivatives of Cyclopehtane and cyclohexane. Thus, methylcyclohexane in the presence of a nickel-silica-alumina catalyst at 290-370 C and in the presence of hydrogen gives a mixture of 1,1-, 1,2-, and 1,3-dimethyIcyclopentanes and some ethyl-cyclopentane. ... 

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