What is a Monosubstituted Cycloalkane?
What is a Monosubstituted Cycloalkane?
MONOSUBSTITUTED CYCLOHEXANES. CONFORMATIONAL ANALYSIS. A substituent group in a substituted cyclohexane, such as the methyl group in methyl cyclo- hexane, can be in either an equatorial or an axial position. These two compounds are not identical, yet they have the same connectivity, so they are stereoisomers.
What is a disubstituted cyclohexane?
In the case of 1,1-disubstituted cyclohexanes, one of the substituents must necessarily be axial and the other equatorial, regardless of which chair conformer is considered. Since the substituents are the same in 1,1-dimethylcyclohexane, the two conformers are identical and present in equal concentration.
Why is it called 1/3-Diaxial?
The energy difference between the two conformations comes from strain, called 1,3-diaxial interactions, created when the axial methyl group experiences steric crowding with the two axial hydrogens located on the same side of the cyclohexane ring.
What is angle strain?
Angle strain is the increase in potential energy of a molecule due to bond angles deviating from the ideal values. In the planar cyclopropane ring the internal bond angle at each carbon atom is 60º.
Why is a 1/3 cis disubstituted cyclohexane?
Cis and trans stereoisomers of 1,3-dimethylcyclohexane The other conformer has both methyl groups in equatorial positions thus creating no 1,3-diaxial interaction. Because the methyl groups are not on adjacent carbons in the cyclohexane rings gauche interactions are not possible.
Which mono substitute is more stable cyclohexane?
equatorial-conformer
For mono-substituted cyclohexane, the equatorial-conformer is more stable than the axial-conformer because of the 1,3-diaxal interaction. Since 1,3-diaxal interaction is essentially the steric strain, so the larger the size of the substituent, the greater the interaction is.