Quiz - Cycloalkanes - 2 | Cycloalkanes

Organic Chemistry 1 - Quiz - Cycloalkanes - 2


Which conformation of cyclohexane minimizes both torsional and angle strain?

Chair conformation is the most stable conformation of cyclohexane because it has all of the C-H bonds staggered and the bond angles are approximately 109.5 degrees, which minimizes both torsional and angle strain.


What is the result of the ring-flipping process in cyclohexane?

Ring-flipping in cyclohexane results in the conversion of axial substituents to equatorial positions and vice versa, without changing the stability of the molecule or creating new isomers.


Which statement best describes the conformational isomerism in cycloalkanes?

Conformational isomers or conformers are the result of rotation around single bonds, which is usually not restricted. However, in cycloalkanes, particularly in structures like cyclohexane, there is restricted rotation leading to stable conformations, such as the chair conformation.


In the context of cycloalkane strain, what does the term 'pseudorotation' refer to?

Pseudorotation refers to the rapid interconversion between conformational isomers of cycloalkanes, especially in the chair conformation of cyclohexane, where the molecule passes through several different states while maintaining overall stability.


Which of the following is not true about substituents on a cyclohexane ring in the chair conformation?

It is not true that large substituents prefer the axial position due to steric hindrance; in fact, large substituents prefer the equatorial position because it offers less steric hindrance compared to the axial position.


What is the consequence of the presence of a bulky substituent on the conformations of cyclohexane?

A bulky substituent on a cyclohexane ring will prefer the equatorial position, due to less steric hindrance, leading to a preference for one chair conformation over the other where the bulky group is equatorial.


How do gauche interactions differ from anti interactions in cyclohexane conformational analysis?

Gauche interactions relate to the steric strain that occurs when substituents are close to each other (60 degrees apart), while anti interactions are more stable as the groups are directly opposite each other (180 degrees), resulting in less steric hindrance in cyclohexane.


In cycloalkane nomenclature, what does a prefix like 'cis-' or 'trans-' indicate?

'Cis-' or 'trans-' prefixes in cycloalkane nomenclature indicate the geometric configuration of substituents in relation to the ring's plane; 'cis-' means on the same side, while 'trans-' means on opposite sides.


Which factor does not influence the stability of cycloalkane conformations?

Hydrogen bonding between substituents is not typically a factor that affects the stability of cycloalkane conformations. Rather, ring strain, steric effects, and, torsional strain govern the stability.


Which cycloalkane is expected to have the least angle strain?

Cyclohexane is known to have the least angle strain among common cycloalkanes due to its chair conformation, which allows bond angles to approximate the tetrahedral angle of 109.5 degrees, resulting in low angle strain.