For each of the following disubstituted cyclohexanes, indicate whether the substituents in the two chair conformers are both equatorial in one chair conformer and both axial in the other or one equatorial and one axial in each of the chair conformers: c. cis-1,3- d. trans-1,3-

Verified step by step guidance

1. Identify the structure of the cyclohexane ring and the positions of the substituents. For 1,3-disubstituted cyclohexanes, the substituents are on carbon 1 and carbon 3.
2. Determine the stereochemistry of the substituents. For cis-1,3-disubstituted cyclohexanes, both substituents are on the same side of the ring. For trans-1,3-disubstituted cyclohexanes, the substituents are on opposite sides.
3. Draw the two possible chair conformations for the cyclohexane ring. Remember that each carbon in the chair conformation has one axial and one equatorial position.
4. For cis-1,3-disubstituted cyclohexanes, place both substituents in either axial or equatorial positions in one chair conformation. In the other chair conformation, one substituent will be axial and the other equatorial.
5. For trans-1,3-disubstituted cyclohexanes, place one substituent in an axial position and the other in an equatorial position in both chair conformations.

Key Concepts

Chair Conformation

Chair conformation is the most stable form of cyclohexane, allowing for minimized steric strain. In this conformation, carbon atoms are arranged in a staggered manner, which provides two types of positions for substituents: equatorial (pointing outward) and axial (pointing up or down). Understanding chair conformations is crucial for analyzing the spatial arrangement of substituents in disubstituted cyclohexanes.

Substituent Positioning

In disubstituted cyclohexanes, the positioning of substituents (axial or equatorial) significantly affects the molecule's stability and reactivity. Axial substituents can lead to 1,3-diaxial interactions, increasing steric strain, while equatorial substituents are generally more stable. Recognizing how substituents are arranged in different chair conformers is essential for predicting the preferred conformation.

Cis and Trans Isomerism

Cis and trans isomerism refers to the relative positioning of substituents on a cyclohexane ring. In cis isomers, substituents are on the same side of the ring, while in trans isomers, they are on opposite sides. This distinction influences the conformational analysis of cyclohexanes, as it determines whether substituents can occupy equatorial or axial positions in the chair conformers.