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Tutorial topics: Introduction Viewing Basics Molecular Shapes (VSEPR) Conformations Ethane Butane Cycloalkanes Substituted Cyclohexane Sterochemistry SN2 Reaction SN1 Reaction Aromaticity

Substituted Cyclohexane: Axial vs. Equatorial In substituted cyclohexanes, the substituents can occupy either axial or equatorial position. In general, the larger group tends to prefer the equatorial position in order to avoid 1,3-diaxial interactions, thus leading to a lower energy. In this tutorial, we will examine the mono- and di-substituted cyclohexanes - their conformations as well as their stereochemistry. Methylcyclohexane-axial Methylcyclohexane-equatorial Which methylcyclohexane conformation is of higher energy (less stable)? Di-substituted cyclohexanes cis-1,2-Dimethylcyclohexane cis-1,2-Dimethylcyclohexane (animating) As ring-flip occurs, which conformation of cis-1,2-dimethylcyclohexane is more stable? trans-1,2-Dimethylcyclohexane trans-1,2-Dimethylcyclohexane trans-1,2-Dimethylcyclohexane (animating) Which conformation of trans-1,2-dimethylcyclohexane is more stable? What is the relationship between cis and trans-1,2-dimethylcyclohexane?