13. Alkenes, Alkynes, and Aromatic Compounds

Using condensed structural formulas, draw three conformers of hexane.

Draw a condensed structural formula and give the correct IUPAC name for the three alkane structural isomers with the molecular formula C₅H₁₂ .

How many structural isomers are possible for the molecular formula C₅H₁₁F? Draw the skeletal structure and give the IUPAC name of each compound.

Using wedge-and-dash bonds, draw a cis and a trans stereoisomers for each of the following compounds:

(b) 1-bromo-2-ethylcyclopentane

Using wedge-and-dash bonds, draw both the cis and trans stereoisomers for each of the following compounds:

(b) 1,3-diethylcyclobutane

For each of the following compounds, indicate whether or not it can exist as cis–trans stereoisomers. If it can exist as the two isomers, draw both as a condensed structure.

(a) H₂C=CHCH₂CH₃

For each of the following compounds, indicate whether or not it can exist as cis–trans stereoisomers. If it can exist as the two isomers, draw both as a condensed structure.

(d)

For each of the following compounds, indicate whether or not it can exist as cis–trans stereoisomers. If it can exist as the two isomers, draw both as a condensed structure.

(c)

Determine whether each of the following is the cis or the trans stereoisomer: 

(c)

Determine whether each of the following is the cis or the trans stereoisomer:

(b)

Are the following compounds structural isomers, cis–trans isomers, or enantiomers?

(c) 

For each pair of molecules, identify the pair as:

A. structural isomers.

B. the same molecule (conformational isomers).

C. cis–trans stereoisomers.

D. different molecules.                                                                                                                                                                 

(b)

The structure of vitamin A is shown in Problem 4.54. Is the double bond nearest the ring on the carbon chain cis or trans?

The vision process in animals involves the change of one double bond in retinal from its cis form to its trans form. The structures of cis and trans retinal are shown below. Label which is cis and which is trans.