Using the table below, calculate the difference in energy between a) the lowest energy conformations of...
Using the table below, calculate the difference in energy between
a) the lowest energy conformations of cis- and trans-1,2-dimethylcyclohexane.
b) the highest and lowest energy conformations of methyl cyclohexane, trans-1,2-dimethylcyclohexane and cis-1,3-dimethylcyclohexane
| Type of Strain Interaction | Associated Energy |
| Eclipsing of a pair of H's | 4kj/mol |
| Eclipsing of a H and a CH3 group | 6kj/mol |
| Eclipsing of a pair of CH3 groups | 11kj/mol |
| Gauche (60) Interactin between CH3 Groups | 3.8 kj/mol |
| 1,3 CH3 to H Interaction on Cyclohexane Chair | 3.8kj/mol |
| 1,3 CH3 to CH3 Interaction on Cyclohexane Chair | 15.5kj/mol |
Homework Answers
1) Difference in lowest energy conformations = 7.6-3.8 = 3.8
2) difference in highest energy conformations =15.2 - 7.6 = 7.6
The lowest energy conformation of methycyclohexane = 0
The highest energy conformation of methylcyclohexane = 7.6 KJ / mole
difference =7.6
b) the energy difference between trans-1,2-dimethylcyclohexane = 15.2-3.8 KJ /mole = 11.4 KJ / mole
c) The energy of lowest conformation of 1,3-dimethylcyclohexane = 0
The energy of highest conformation of 1.3-dimethylcyclohexane = 15.5 KJ / mole
Add Answer to:
Using the table below, calculate the difference in energy
between
a) the lowest energy conformations of...
a. Use strain energy increments in the OWL Table Reference (see References button, Strain Energy Increments) to calcula...
a. Use strain energy increments in the OWL Table Reference (see References button, Strain Energy Increments) to calculate the energy difference between the two chair conformations of the compound below. b. Specify substituent positions axial or equatorial) in the more stable chair. c. Estimate the percent of the more stable chair at equilibrium at 25°C. (To determine the percent of the more stable chair at equilibrium, first calculate Keq, and then use this value to find the percentage.) A CH3...
a. Use strain energy increments in the OWL Table Reference (see References button, Strain Energy Increments)...
a. Use strain energy increments in the OWL Table Reference (see References button, Strain Energy Increments) to calculate the energy difference between the two chair conformations of the compound below. b. Specify substituent positions (axial or equatorial) in the more stable chair. c. Estimate the percent of the more stable chair at equilibrium at 25°C. (To determine the percent of the more stable chair at equilibrium, first calculate Keq, and then use this value to find the percentage.) OH H3C...
Help if you can, don’t worry about # 4 Questions Which of the two conformations is...
Help if you can, don’t worry about # 4
Questions Which of the two conformations is favored at equilibrium? a. trans-1,2-dimethylcyclohexane (a/aor b. cis-1,3-dimethylcyclohexane (a/a)or 1. (ele) (ele) 2. How many gauche interactions are present in the trans 1.2-dimethylcyclohexane (a/a) conformer between the methyl groups and between the methy)l groups and the a. b. 2 c. 3 d. 4 e. None 3. How many gauche interactions are present in the trans-1,2-dimethylcyclohexane (e/e) conformer between the methyl groups and between the...
5.5. Place the methyl groups by drawing the axial and equatorial positions on the cyclohexane structure...
5.5. Place the methyl groups by drawing the axial and equatorial positions on the cyclohexane structure in the chair conformations next to the cyclohexane derivatives named below. H H CH, H CH, CH, cis-1,2-Dimethylcyclohexane H CH, trans-1,2-Dimethylcyclohexane H CH, H CH, CH, eis-1,3-Dimethylcyclohexane CH, trans-1,3-Dimethylcyclohexane H H H CH, KO HC CH, cis-1,4-Dimethylcyclohexane н,с H trans-1,4-Dimethyleyclohexane
Following are the alternative chair conformations for trans-1,4-dimethylcyclohexane: . Using the data for ΔG for monosubstituted...
Following are the alternative chair conformations for
trans-1,4-dimethylcyclohexane:
.
Using the data for ΔG for monosubstituted cyclohexanes at room
temperature (25ºC) and the representative value* for the gauche
interaction of two equatorially positioned substituents in the
1,2-position:
a) Calculate the difference in the Gibbs free energy between
the second and first conformation including the algebraic sign.
kJ/mol
b) Given your value in (a), calculate the percent of the
chair, indicated as B, presented in an equilibrium mixture of the
conformers...
9. Draw two different chair conformations of cyclohexanol, showing all hydropen atoms. Identify each position as...
9. Draw two different chair conformations of cyclohexanol, showing all hydropen atoms. Identify each position as axial or equatorial 10. Draw the most stable chair conformation of the following molecules, and estimate the amount of strain in each: (a) trans-1-Chloro-3-methylcyclohexane (b) cis-1-Ethyl-2-methylcyclohexane (c) cis-1-Bromo-4-ethylcyclohexane (d) cis-1-tert-Butylcyclohexane 11. Which isomer is more stable, cis-decalin or trans-decalin? Explain. 12. Glucose exists in two forms having a 36:64 ratio at equilibrium. Draw a skeletal structure of each, describe the difference between them and...
Strain Energy Increments Strain Energy for Alkanes Interaction/Compound kJ/mol kcal/ 4.0 H: Heclipsing 1.0 H: CH3...
Strain Energy Increments Strain Energy for Alkanes Interaction/Compound kJ/mol kcal/ 4.0 H: Heclipsing 1.0 H: CH3 eclipsing 5.8 1.4 CH3 : CH3 eclipsing 11.0 2.6 gauche butane 3.8 0.9 cyclopropane 115 27.5 cyclobutane 110 26.3 cyclopentane 26.0 6.2 6.3 cycloheptane 26.2 cyclooctane 40.5 9.7 Axial Strain Energies for Monosubstituted Cyclohexanesab This table gives the sum of the values for the 1,3 diaxial interactions of the substituent with two hydrogen atoms. kJ/mol kcal/mol Substituent(solvent) -CH3 1.7 7.3 CH2CH3 7.5 1.8 -CH(CH3)2...
6. Build the cyclobutane ring and study the angle strain and torsional strain. Draw the structures to explain thes...
6. Build the cyclobutane ring and study the angle strain and torsional strain. Draw the structures to explain these factors. 7. The conformation of cyclobutane is slightly folded. Folding gives partial relief from the eclipsing of bonds, as shown in the Newman projection. Compare this actual structure with the hypothetical planar structure. Draw the relevant structures. 8. trans-1,2-Dimethylcyclobutane is more stable than cis-1,2-dimethylcyclobutane, but cis-1,3- dimethylcyclobutane is more stable than trans-1,3-dimethylcyclobutane. Use the molecular models to find the reasons for...
b. Which of the following alkanes has the highest bolling point? 2,3-dimethylbutane: 2-methylpentane; 3-methylpentane; hexane c....
b. Which of the following alkanes has the highest bolling point? 2,3-dimethylbutane: 2-methylpentane; 3-methylpentane; hexane c. Which of the following compounds can adopt a chair conformation in which there are no axial methyl groups? 1,1-dimethylcyclohexane; cis-1,2-dimethylcyclohexane; trans-1,2-dimethylcyclohexane; trans-1,3-di methylcyclohexane d. Which of the following compounds can adopt a chair conformation which there are no axial methyl groups? cis-1,2-dimethylcyclohexane; cis-1,3-dimethylcyclohexane; trans-1,3-dimethylcyclohexane; cis-1.4-dimethylcyclohexane cis-1,2-dimethvcyclohexane (Enter the numerical value only, without any units)? e. What is the approximate di hedral angle between the...
Identify and count the interactions that destabilize the following conformation, and compute its strain energy using...
Identify and count the interactions that destabilize the following conformation, and compute its strain energy using the values provided in the table. (Be sure to specify units and to enter zero for interactions not present.) HCH3 Hafa C CH Strain Energy Increments H Interaction Strain (kJ/mol) H eclipsing 4.0 H CH3 eclipsing 6.0 CH3 CH3 eclipsing 11.0 CH3 – CH3 gauche 3.8 H-H eclipsing C H -CH: eclipsing C CH3-CH3 eclipsing C CH3-CH3 gauche Total strain energy is kJ/mol
a. Use strain energy increments in the OWL Table Reference (see References button, Strain Energy Increments) to calculate the energy difference between the two chair conformations of the compound below. b. Specify substituent positions axial or equatorial) in the more stable chair. c. Estimate the percent of the more stable chair at equilibrium at 25°C. (To determine the percent of the more stable chair at equilibrium, first calculate Keq, and then use this value to find the percentage.) A CH3...
a. Use strain energy increments in the OWL Table Reference (see References button, Strain Energy Increments) to calculate the energy difference between the two chair conformations of the compound below. b. Specify substituent positions (axial or equatorial) in the more stable chair. c. Estimate the percent of the more stable chair at equilibrium at 25°C. (To determine the percent of the more stable chair at equilibrium, first calculate Keq, and then use this value to find the percentage.) OH H3C...
Help if you can, don’t worry about # 4
Questions Which of the two conformations is favored at equilibrium? a. trans-1,2-dimethylcyclohexane (a/aor b. cis-1,3-dimethylcyclohexane (a/a)or 1. (ele) (ele) 2. How many gauche interactions are present in the trans 1.2-dimethylcyclohexane (a/a) conformer between the methyl groups and between the methy)l groups and the a. b. 2 c. 3 d. 4 e. None 3. How many gauche interactions are present in the trans-1,2-dimethylcyclohexane (e/e) conformer between the methyl groups and between the...
5.5. Place the methyl groups by drawing the axial and equatorial positions on the cyclohexane structure in the chair conformations next to the cyclohexane derivatives named below. H H CH, H CH, CH, cis-1,2-Dimethylcyclohexane H CH, trans-1,2-Dimethylcyclohexane H CH, H CH, CH, eis-1,3-Dimethylcyclohexane CH, trans-1,3-Dimethylcyclohexane H H H CH, KO HC CH, cis-1,4-Dimethylcyclohexane н,с H trans-1,4-Dimethyleyclohexane
Following are the alternative chair conformations for
trans-1,4-dimethylcyclohexane:
.
Using the data for ΔG for monosubstituted cyclohexanes at room
temperature (25ºC) and the representative value* for the gauche
interaction of two equatorially positioned substituents in the
1,2-position:
a) Calculate the difference in the Gibbs free energy between
the second and first conformation including the algebraic sign.
kJ/mol
b) Given your value in (a), calculate the percent of the
chair, indicated as B, presented in an equilibrium mixture of the
conformers...
9. Draw two different chair conformations of cyclohexanol, showing all hydropen atoms. Identify each position as axial or equatorial 10. Draw the most stable chair conformation of the following molecules, and estimate the amount of strain in each: (a) trans-1-Chloro-3-methylcyclohexane (b) cis-1-Ethyl-2-methylcyclohexane (c) cis-1-Bromo-4-ethylcyclohexane (d) cis-1-tert-Butylcyclohexane 11. Which isomer is more stable, cis-decalin or trans-decalin? Explain. 12. Glucose exists in two forms having a 36:64 ratio at equilibrium. Draw a skeletal structure of each, describe the difference between them and...
Strain Energy Increments Strain Energy for Alkanes Interaction/Compound kJ/mol kcal/ 4.0 H: Heclipsing 1.0 H: CH3 eclipsing 5.8 1.4 CH3 : CH3 eclipsing 11.0 2.6 gauche butane 3.8 0.9 cyclopropane 115 27.5 cyclobutane 110 26.3 cyclopentane 26.0 6.2 6.3 cycloheptane 26.2 cyclooctane 40.5 9.7 Axial Strain Energies for Monosubstituted Cyclohexanesab This table gives the sum of the values for the 1,3 diaxial interactions of the substituent with two hydrogen atoms. kJ/mol kcal/mol Substituent(solvent) -CH3 1.7 7.3 CH2CH3 7.5 1.8 -CH(CH3)2...
6. Build the cyclobutane ring and study the angle strain and torsional strain. Draw the structures to explain these factors. 7. The conformation of cyclobutane is slightly folded. Folding gives partial relief from the eclipsing of bonds, as shown in the Newman projection. Compare this actual structure with the hypothetical planar structure. Draw the relevant structures. 8. trans-1,2-Dimethylcyclobutane is more stable than cis-1,2-dimethylcyclobutane, but cis-1,3- dimethylcyclobutane is more stable than trans-1,3-dimethylcyclobutane. Use the molecular models to find the reasons for...
b. Which of the following alkanes has the highest bolling point? 2,3-dimethylbutane: 2-methylpentane; 3-methylpentane; hexane c. Which of the following compounds can adopt a chair conformation in which there are no axial methyl groups? 1,1-dimethylcyclohexane; cis-1,2-dimethylcyclohexane; trans-1,2-dimethylcyclohexane; trans-1,3-di methylcyclohexane d. Which of the following compounds can adopt a chair conformation which there are no axial methyl groups? cis-1,2-dimethylcyclohexane; cis-1,3-dimethylcyclohexane; trans-1,3-dimethylcyclohexane; cis-1.4-dimethylcyclohexane cis-1,2-dimethvcyclohexane (Enter the numerical value only, without any units)? e. What is the approximate di hedral angle between the...
Identify and count the interactions that destabilize the following conformation, and compute its strain energy using the values provided in the table. (Be sure to specify units and to enter zero for interactions not present.) HCH3 Hafa C CH Strain Energy Increments H Interaction Strain (kJ/mol) H eclipsing 4.0 H CH3 eclipsing 6.0 CH3 CH3 eclipsing 11.0 CH3 – CH3 gauche 3.8 H-H eclipsing C H -CH: eclipsing C CH3-CH3 eclipsing C CH3-CH3 gauche Total strain energy is kJ/mol
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