ollowing are the alternative chair conformations for trans-2-methylcyclohexanamine: NH₂ Group C=N Br CH3 B Using the data for AG for monosubstituted cyclohexanes at room temperature (25°C) and the representative value for the gauche interaction of two equatorially positioned substituents in the 1,2-position: OH axial AG (kJ/mol) -0.8 -2.4 CH3 -3.9 -NH₂ equatorial Group NH₂ CH3 1,2-gauche AG (kJ/mol) -5.9 -7.3 3.8 a) Calculate the difference in the Gibbs free energy between the second and first conformation including the algebraic sign. b) Given your value in (a), calculate the percent of the chair, indicated as B, presented in an equilibrium mixture of the conformers at 25°C. *The actual value will depend on the substituents. The values of the gas constant and the temperature for 25°C are 8.314 JK mol¹ and 298 K respectively. kJ/mol %

Consider the following reaction. (a) Draw a structural formula for the compound with the molecular formula C8H12. (b) Do you predict the product to be the cis isomer, the trans isomer, or a mixture of cis and trans isomers? Explain. (c) Draw a suitable stereorepresentation for the more stable chair conformation of the dicarbaldehyde formed in this oxidation.

Draw both cis- and trans-1,4-dimethylcyclohexane in their more stable chair conformations. 5-72 (a) How many stereoisomers are there of cis-1,4-dimethylcyclohexane, and how many of trans-1,4-dimethylcyclohexane? (b) Are any of the structures chiral? (c) What are the stereochemical relationships among the various stereoisomers of 1,4-dimethylcyclohexane?

Answer the following:

Which of the following two conformations of cis-1-bromo-4-methylcyclohexane is more stable? Use the strain energy increments in the table below estimate the energy difference (a positive number) between them.

Cyclohexane derivatives exist primarily in the most stable of the available chair conformations. Give the position, axial or equatorial, of each of the three groups shown when the ring is in the most stable chair conformation. If a group divides its time equally between axial and equatorial positions, indicate this with ax/eq.

Q8 Conformational Analysis of Cycloalkanes In this question you will look at the conformations of the following molecule: CH3 C В F CH3 D -E A H3C F I II Energy Costs for Interactions in Alkane Conformers: Computed Energy Cost (kJ/mol)* 3.8 Interaction H+H eclipsed H+CH3 eclipsed CH3+CH3 eclipsed CH3+CH3 gauche H»CH(CH3)2 gauche H CH(CH:)2 eclipsed CH3+CH(CH3)2 gauche CH3+CH(CH3)2 eclipsed HeC(CH:)3 eclipsed CH3+C(CH3)3 gauche CH3+C(CH:)3 eclipsed H+I eclipsed I+CH3 gauche I+CH3 eclipsed "Values computed with Gaussian09 using B3LYP/6-31G(d) for structure optimization and B3LYP/6-311+G(2df,3p) for the conformation energy. The calculations were performed in the gas phase (no solvent). *This result for t-butyl is a bit peculiar given that the value is less than that for isopropyl, but there is an explanation that I can tell you about in office hours! 4.8 12.6 3.7 (0.0) 3.1 3.6 17.3 2.8 13.6 18.7 6.7 1.2 15.5 Steric Strain in Monosubstituted Cyclohexanes: 1,3-Diaxial strain Y (kJ/mol)…

Identify the most stable conformation for 1 tert-butyl-3-methlyclohexane

Which of the staggered conformations of 2-methylbutane is most stable? CH₂ CH₂ H₂CH₂ H CH₂ H CH₂ H₂C CH₂ CH₂ þ þ a o H H H H H HCH: H CH₂ CH₂ H D B Multiple Choice O O A B D

Calculate ASºffor the following compounds in J mol-¹ K-¹. C₂H4(g) AS°f= Your answer is incorrect. AS°f= HC₂H3O2(1) J mol-¹ K-¹ Your answer is incorrect. J mol-¹ K-¹