Stability of Cis and Trans Isomers

The video tutorial covers the positioning of substituents on cyclohexane rings, emphasizing the preference for equatorial positions to avoid 1,3-diaxial repulsion. It introduces disubstituted cycloalkanes, focusing on dimethylcyclopropanes and their cis and trans isomers. The tutorial explains the stability differences between these isomers, highlighting that trans isomers are generally more stable due to reduced steric strain. The video also explores six-membered rings, discussing the impact of ring flips on stability and the importance of axial and equatorial positions.

Why do substituents on cyclohexane rings prefer equatorial positions?

• To increase torsional strain

• To avoid 1,3-diaxial repulsion

• To enhance eclipsed interactions

• To decrease molecular weight

What distinguishes cis and trans isomers in dimethylcyclopropanes?

• The position of methyl groups

• The number of carbon atoms

• The presence of a double bond

• The type of chemical bonds

Which isomer of dimethylcyclopropane is more stable and why?

• Cis, due to lower steric strain

• Trans, due to lower steric strain

• Cis, due to higher energy release

• Trans, due to higher energy release

What is the main reason for the greater stability of trans isomers compared to cis isomers?

• Higher angle strain

• Lower molecular weight

• Lower steric strain

• Higher torsional strain

What type of strain is minimized in trans isomers?

• Torsional strain

• All of the above

• Angle strain

• Steric strain

How can six-membered rings relieve undesirable interactions?

• By reducing the number of carbon atoms

• By forming more cis isomers

• By increasing torsional strain

• By flipping the ring

What determines the stability of cis and trans isomers in six-membered rings?

• The type of chemical bonds

• The number of hydrogen atoms

• The position of methyl groups

• The presence of a double bond

Which isomer is more stable in a 1,2-dimethylcyclohexane?

• Neither is stable

• Cis isomer

• Trans isomer

• Both are equally stable

What is the effect of axial positions on the stability of cyclohexane isomers?

• Increases stability

• Decreases stability

• Has no effect

• Depends on the substituent

In a 1,4-dimethylcyclohexane, which isomer is generally more stable?

• Both are equally stable

• Cis isomer

• Trans isomer

• Neither is stable