Hydrogen molecular models

Figure 2-100. CORINA-generated 3D molecular model of a fullerene dendrlmer with 1278 atoms (762 non-hydrogen atoms).

Like hydrogen peroxide the inorganic substances hydrazine (H2NNH2) and hydroxylamine (H2NOH) possess conformational mobility Wnte stmctural representations or build molecular models of two different staggered conformations of (a) hydrazine and (b) hydroxylamine... 

The stereoselectivity of this reaction depends on how the alkene approaches the catalyst surface As the molecular model m Figure 6 3 shows one of the methyl groups on the bridge carbon lies directly over the double bond and blocks that face from easy access to the catalyst The bottom face of the double bond is more exposed and both hydrogens are transferred from the catalyst surface to that face... 

Compound A undergoes catalytic hydrogenation much faster than does compound B Why" Making molecular models will help... 

There are two products that can be formed by syn addition of hydrogen to 2 3 dimethylbi cyclo[2 2 1] 2 heptene Write or make molecular models of their structures... 

Hydrogenation of 3 carene is in pnnciple capable of yielding two stereoisomenc products Wnte their structures Only one of them was actually obtained on catalytic hydrogenation over platinum Which one do you think is formed" Explain your reasoning with the aid of a drawing or a molecular model... 

Construct a molecular model of the product formed by catalytic hydrogenation of 1 2 dimethylcyclohexene Assume syn addition occurs... 

Construct molecular models of the gauche and anti conformations of 1 2 ethanediol and explore the possibility of intramolecular hydrogen bond formation in each one... 

Intramolecular hydrogen bonding is present in the chiral diastereomer of 225 5 tetra methylhexane 3 4 diol but absent in the meso diastereomer Construct molecular models of each and suggest a reason for the difference between the two... 

Construct a molecular model of cyclohexanone Do either of the hydrogens of C 2 eclipse the carbonyl oxygen" ... 

Various equations of state have been developed to treat association ia supercritical fluids. Two of the most often used are the statistical association fluid theory (SAET) (60,61) and the lattice fluid hydrogen bonding model (LEHB) (62). These models iaclude parameters that describe the enthalpy and entropy of association. The most detailed description of association ia supercritical water has been obtained usiag molecular dynamics and Monte Carlo computer simulations (63), but this requires much larger amounts of computer time (64—66). 

The configuration was assigned after oxidation of (43) and (44) to the corresponding 3,20-diketones. The diketone obtained from (44) showed an intramolecular bonded hydroxyl absorption at 3450 cm h Inspection of molecular models indicates that only a 12 -hydroxyl function can form an internal hydrogen bond to the 20-carbonyl group. 

As useful as molecular models are, they are limited in that they only show the location of the atoms and the space they occupy. Another important dimension to molecular structure is its electron distribution. We introduced electrostatic potential maps in Section 1.5 as a way of illustrating charge distribution and will continue to use them throughout the text. Figure 1.6(d) shows the electrostatic potential map of methane. Its overall shape is similar to the volume occupied by the space-filling model. The most electron-rich regions are closer to carbon and the most electron-poor ones are closer to the hydrogens. 

Problem 1.8 concerned the charge distribution in methane (CH4), chloromethane (CH3CI), and methyllithium (CH3Li). Inspect molecular models of each of these compounds, and compare them with respect to how charge is distributed among the various atoms (carbon, hydrogen, chlorine, and lithium). Compare their electrostatic potential maps. 

Two stereoisomers of l-bromo-4-methylcyclohexane are formed when trans-4-methyl-cyclohexanol reacts with hydrogen bromide. Write structural formulas or make molecular models of ... 

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