Concept explainers
Interpretation:
The amount of steric strain in each of the chair conformers of
Concept introduction:
Strain energy: Ring strain is a type of instability that exists when bonds in a molecule form angles that are abnormal. Strain is most commonly discussed for small rings such as cyclopropanes and cyclobutanes, whose internal angles are substantially smaller than the idealized value of approximately 109°.
Angle strain of cyclic molecules: The German chemist Adolf van Baeyer, believing that all cyclic molecules like planner, proposed that the stability of a cycloalkane could be predicated by determining the difference between this ideal bond angle and the bond angle in the planner cycloalkane.
We consider the simple example of the bond angle in cyclopropane are 600 degree repressing a 45.50 degree it deviation from 109.50, it is proved from Baeyer this deviation cause angle strain which decrease respective molecules stability.
The corresponding Bond strain formula shown below
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Essential Organic Chemistry (3rd Edition)
- Gibbs free energy differences between axial-substituted and equatorial-substituted chair conformations of cyclohexane were given in Table 2.4. (a) Calculate the ratio of equatorial to axial tert-butylcyclohexane at 25C. (b) Explain why the conformational equilibria for methyl, ethyl, and isopropyl substituents are comparable but the conformational equilibrium for tert-butylcyclohexane lies considerably farther toward the equatorial conformation.arrow_forwardConsider 1-bromo-2-methylpropane and draw the following. (a) The staggered conformation(s) of lowest energy (b) The staggered conformation(s) of highest energyarrow_forwardmyo-Inositol, one of the isomers of 1,2,3,4,5,6-hexahydroxycyclohexane, acts as a growth factor in both animals and microorganisms. Draw the most stable chair conformation of myo-inositol.arrow_forward
- Ketones react with alcohols to yield products called acetals. Why does the all-cis isomer of 4-tert-butyl-1,3-cyclohexanediol react readily with acetone and an acid catalyst to form an acetal, but other stereoisomers do not react? In formulating your answer, draw the more stable chair conformations of all four stereoisomers and the product acetal for each one.arrow_forward6) Draw the energetically favored (more stable) chair conformer of the following cyclohexane. H3C OH 110arrow_forwardIndicate the position, axial or equatorial, of the substituents in the more stable chair conformation. CH3 Methyl is [A] OH is [B] Isopropyl is [C] Cl is [D] HO` CIarrow_forward
- 13 Draw the molecule trans-1-ethyl-3- isopropylcyclohexane conformation. Which is the overall most-stable conformer? Justify your answer. in its chair and its flipped chairarrow_forwardConstruct the chair structures with the molecular models for trans-1-ethyl-3-methylcyclohexane. Find the energy of each conformer, the equilibrium constant Keq, and the percentage of each conformer at 25oC. Indicate which conformer is more stable.arrow_forwardCyclohexane 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.arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning