Ethyl-cyclopentane

These heat of formation parameters may be considered as shifting the zero point of Fpp to a common origin. Since corrections from larger moieties are small, it follows that energy differences between systems having the same groups (for example methyl-cyclohexane and ethyl-cyclopentane) can be calculated directly from differences in steric energy. 

In the case of iridium, complex [IrH2(PPh3)2(acetone)2] BF4 (11) was the first to carry out catalytically the dehydrogenation of cycloalkanes [13, 14]. However, it was later realized that the halocarbons used as solvents reacted with 11 to produce the stable species [HL2lr(p-Cl)2(. i-X)IrL2H]BF4 (X = Cl (14) or H (15)) [16] (Scheme 13.8), and that elimination of the solvent by running the reactions in neat alkane not only improved yields but also permitted the activation of other previously unreactive cycloalkanes, such as methyl- and ethyl-cyclopentane. However, it was also noted that the system in some cases was not catalytic, due mainly to decomposition of the catalyst at the temperatures employed [16]. 

A mixture of cis and trans-1,2-dim ethyl cyclopentanes will be ormed as the stereochemical integrity of the molecule would be destroyed on opening of the ring. 

Turova-Polyak and co-workers have carried out extensive studies of naphthene isomerization with AICI3, particularly of the substituted cyclopentanes. The conversion of mono- and disubstituted cyclopentanes to cyclohexanes was reported as an analytical technique for the determination of cyclopentanes in mixture with paraffins (411). Ethyl-cyclopentane at room temperature gave an 18-20% yield of cyclohexane derivatives (412). At 140-145°, an 85% yield of 1,3,5-trimethyl-cyclohexane was obtained. This work was also extended to 1,1-dimethyl-cyclopentane (410), up to 95% of which was converted to methyl-cyclohexane at 115°. Similar conversions of alkylated cyclopentanes were also reported by Shulkin and Plate (375). These researches parallel similar work done in the United States. 

Figure 1. The content of a) C5 b) and c) C7 components in the naphthas as a function of the initial boiling point (IBP). CP=cyclopentane MCP=methylcyclopentane C7CP=dimethyl- and ethyl -cyclopentane CH=cyclohexane MCH=methylcyclohexane BEN=benzene TOL=toluene.

C8H16 1-methyl-trans-2-ethyl cyclopentane 930-90-5 167.25 11.482 2 14946 C8H16 2,4-dimethyl-2-hexene 14255-23-3 145.38 11.845 2... 

C7H14 ethyl cyclopentane 1640-89-7 9.440E+09 70.400 13446 C8H803 vanillin 121-33-5 1.045E+10 81.350... 

Assume that you have two unlabeled samples, one of methylcyclohexane and the other of ethyl cyclopentane. How could you use mass spectrometry to tell them apart The mass spectra of both are shown in Figure 12.6. 

Strategy Look at the two possible structures and decide on how they difTer. Then think about how any of these differences might give rise to differences in mass spectra. Methylcydohexane, for instance, has a -CHa group, and ethyl-cyclopentane has a -CH2CH3 group, which should affect the fragmentation patterns. 

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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