91Ó°ÊÓ

Draw two constitutional isomers of \(c i s-1,2\) -dibromocyclopentane.

Draw a stereoisomer of trans-1,3-dimethylcyclobutane.

Tell whether the following pairs of compounds are identical, constitutional isomers, stereoisomers, or unrelated. (a) cis-1,3-Dibromocyclohexane and trans-1,4-dibromocyclohexane (b) 2,3 -Dimethylhexane and 2,3,3 -trimethylpentane

Draw three isomers of trans-1,2-dichlorocyclobutane, and label them as either constitutional isomers or stereoisomers.

Draw 1,3,5 -trimethylcyclohexane using a hexagon to represent the ring. How many cis-trans stereoisomers are possible?

A 1,2 -cis disubstituted cyclohexane, such as cis-1,2-dichlorocyclohexane, must have one group axial and one group equatorial. Explain.

A 1,2 -trans disubstituted cyclohexane must have either both groups axial or both groups equatorial. Explain.

Why is a 1,3 -cis disubstituted cyclohexane more stable than its trans isomer?

Assume that you have a variety of cyclohexanes substituted in the positions indicated. Identify the substituents as either axial or equatorial. For example, a 1,2 -cis relationship means that one substituent must be axial and one equatorial, whereas a 1,2 -trans relationship means that both substituents are axial or both are equatorial. (a) 1,3 -Trans disubstituted (b) 1,4 -Cis disubstituted (c) 1,3 -Cis disubstituted (d) 1,5 -Trans disubstituted (e) 1,5 -Cis disubstituted (f) 1,6 -Trans disubstituted

Draw the two chair conformations of cis-1-chloro-2-methylcyclohexane. Which is more stable, and by how much?