Cis and Trans, E and Z for Cyclic Compounds

Key Questions

• What are the stereoisomers of cyclic compounds?

  Just as with acyclic compounds, cyclic compounds can have geometric and optical isomers.

  In general, if any two sp³ carbons in a ring have two different substituent groups (not counting other ring atoms), stereoisomerism is possible.

  Consider, for example, 1,2-dimethylcyclopentane.

  

  Geometric Isomers

  1,2-Dimethylcyclopentane exists as the cis isomer, with both CH₃ groups on the same side of the ring, or as the trans isomer, with the CH₃ groups on opposite sides of the ring.

  

  Optical Isomers

  trans-1,2-Dimethylcyclopentane exists as two optical isomers.

  

  They are nonsuperimposable mirror images of each other.

  Ernest Z. · 7 · May 4 2015

• What are geometric isomers? Give me an example
• How can I draw the structural formulas for all the isomers of #C_4H_7Cl#? Are there any enantiomers or diastereomers?
• What are the stereoisomers of cyclic compounds?
• Why is the free single bond rotation restricted in the case of cyclic compounds?
• How many asymmetric centers and stereoisomers does 1-Bromo-3-methylcyclohexane have?
• How many asymmetric centers and stereoisomers does 1-Bromo-2-methylcyclopentane have?
• How many asymmetric centers and stereoisomers does 1-Bromo-4-methylcyclohexane have?
• Of all the possible cyclooctanes that have one chloro substituent and one methyl substituent, which ones do not have any asymmetric centers?
• How do you draw the cis and trans isomers for 1-bromo-4-chlorocyclohexane?
• How can I draw all possible stereoisomers for 1,3-dibromopentane?
• How do you draw the cis and trans isomers for 1-ethyl-3-methylcyclobutane?
• What are the symmetry elements of the isomers of dichlorocyclobutane?