Ethane model structure

Methane and ethane. Lewis structures and ball-and-stick models. 

Prepare a second model of ethane. Replace one hydrogen, any one, on each ethane model with a substituent such as a halogen, to form two models of CH3CH2X. Are the structures identical If not, can they be made identical by rotation about the C—C bond With one of the models, demonstrate that there are three equivalent staggered conformations (see Exercise 3) of CH3CH2X. How many equivalent eclipsed conformations are possible ... 

The structural features of methane ethane and propane are summarrzed rn Ergure 2 7 All of the carbon atoms have four bonds all of the bonds are srngle bonds and the bond angles are close to tetrahedral In the next sectron we 11 see how to adapt the valence bond model to accommodate the observed structures... 

Adsorption of hard sphere fluid mixtures in disordered hard sphere matrices has not been studied profoundly and the accuracy of the ROZ-type theory in the description of the structure and thermodynamics of simple mixtures is difficult to discuss. Adsorption of mixtures consisting of argon with ethane and methane in a matrix mimicking silica xerogel has been simulated by Kaminsky and Monson [42,43] in the framework of the Lennard-Jones model. A comparison with experimentally measured properties has also been performed. However, we are not aware of similar studies for simpler hard sphere mixtures, but the work from our laboratory has focused on a two-dimensional partly quenched model of hard discs [44]. That makes it impossible to judge the accuracy of theoretical approaches even for simple binary mixtures in disordered microporous media. 

The electron diffraction analysis of l,2-bis(methylsulfonyl)ethane, CH3S02CH2CH2S02CH338, yielded a limited amount of structural information. However, this substance has also been studied by X-ray crystallography5, 52, and the two sets of data offer a possibility for comparison. The molecular model is shown in Figure 14. 

Transient computations of methane, ethane, and propane gas-jet diffusion flames in Ig and Oy have been performed using the numerical code developed by Katta [30,46], with a detailed reaction mechanism [47,48] (33 species and 112 elementary steps) for these fuels and a simple radiation heat-loss model [49], for the high fuel-flow condition. The results for methane and ethane can be obtained from earlier studies [44,45]. For propane. Figure 8.1.5 shows the calculated flame structure in Ig and Og. The variables on the right half include, velocity vectors (v), isotherms (T), total heat-release rate ( j), and the local equivalence ratio (( locai) while on the left half the total molar flux vectors of atomic hydrogen (M ), oxygen mole fraction oxygen consumption rate... 

Lewis structure and ball-and-stick models of ethane (a) and propane (b). All the carbon atoms have tetrahedral shapes, because each has four pairs of electrons to separate in three-dimensional space. 

From a structural point of view the OPLS results for liquids have also shown to be in accord with available experimental data, including vibrational spectroscopy and diffraction data on, for Instance, formamide, dimethylformamide, methanol, ethanol, 1-propanol, 2-methyl-2-propanol, methane, ethane and neopentane. The hydrogen bonding in alcohols, thiols and amides is well represented by the OPLS potential functions. The average root-mean-square deviation from the X-ray structures of the crystals for four cyclic hexapeptides and a cyclic pentapeptide optimized with the OPLS/AMBER model, was only 0.17 A for the atomic positions and 3% for the unit cell volumes. 

The elegant models of three-dimensional protein structures, such as those shown in figure 11.3, fail in one respect they provide a sense of a static molecule in space. As we learned from very simple structures such as ethane, molecules are dynamic, changing conformations in space rapidly. This is surely true for proteins as well... 

Many mechanistic implications have been discussed, but we will concentrate here only on the most important structures in the context of dihydrogen-cation complexes. Deuterium-labeled methane and methyl cations were employed to examine the scrambling and dissociation mechanisms. The protonated ethane decomposition yields the ethyl cation and dihydrogen. Under the assumption that the extra proton is associated with one carbon only, a kinetic model was devised to explain the experimental findings, such as H/D scrambling. ... 

In bimetallic catalysts, Cu-Ru is an important system. Combinations of the Group Ib metal (Cu) and Group VIII metal (Ru)-based catalysts are, for example, used for the dehydrogenation of cyclohexane to aromatic compounds and in ethane hydrogenolysis involving the rupture of C-C bonds and the formation of C-H bonds (Sinfelt 1985). Here we elucidate the structural characteristics of supported model Cu-Ru systems by EM methods, including in situ ETEM. 

Figure 5.26. In situ ethane reaction and dynamic ED patterns a) Cu-Ru/C catalyst (room temperature) (Z ) 300 °C with extra rings (c) model of CuRu3 structure observed in dynamic ED. (After Smith et al 1994.)...

Compounds with molecular structures similar to those of the repeating units are called model compounds, and much information about the properties of polymecs may be derived from knowledge of these model compounds. Thus, a person who knows the chemical properties of ethane can fairly well extrapolate this to the chemistry of hdpe. Of course, the physical and thermal properties of hdpe are much different from those of ethane. 

Ball-and-stick models of organic substances provide a convenient means of studying the structures of various organic compounds. Balls with holes represent the atoms, and sticks represent the covalent bonds. Figure 1-3 shows two conformations of ethane in which the dark balls represent carbon and the light balls represent hydrogen. All bond angles are the normal 109.5°. 

In order to investigate the structure of crosslinked polyethylene by, 3C NMR the model compound l,l,2,2-tetra(tridecyl)ethane, i.e. two molecules of n-C27H56 linked at the C-14 atoms, was prepared. The tertiary 13C-14 atoms give rise to a resonance signal at 39.5 ppm. Spectra of long chain n-paraffins eicosane (C20H42) and hexacosane (C26H54) exposed to 5 MGy y-radiation above their respective... 

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