13. Alkenes, Alkynes, and Aromatic Compounds

Draw a constitutional isomer of butane.

Draw all structural isomers for C₃H₈O.

Provide a cis isomer for the following compound.

If one compound has the formula C₅H₁₀ and another has the formula C₄H₁₀ are the two compounds isomers? Explain.

Write condensed structures for the following molecular formulas. More than one isomer will be required for each.

Isomers of C₈H₁₈ that contain two methyl groups and a longest chain of 4 carbons

How many straight-chain isomers can you write that fit the following descriptions? See Worked Example 12.12 for guidance.

Amines (―NH₂) with a longest chain of 7 carbons

How many isomers can you write that fit the following descriptions? See Worked Example 12.12 for guidance.

Alcohols (―OH) formed from 2-methylhexane

Which of the following pairs of structures are identical, which are isomers, and which are unrelated? <IMAGE>

Draw the condensed structural formulas for all the possible alkane isomers that have a total of six carbon atoms and a four-carbon chain. (11.3)

Give IUPAC names for the five isomers with the formula C₆H₁₄.

Predict the products of the following reactions:

e. <IMAGE>

Draw the structural formulas and name all cyclic isomers with the formula C₅H₁₀.

Which of the following substances exist as can cis–trans isomers? Draw both isomers for those that do.

a. 2,3-Dimethyl-2-pentene (condensed structures only)

b. 2-Methyl-2-hexene (both condensed and line structures)

c. 2-Hexene (line structures only)

Write structural formulas for compounds that meet the following descriptions:

a. An alkene, C₆H₁₂, that cannot have cis–trans isomers and whose longest chain is 5 carbons long

Write structural formulas for compounds that meet the following descriptions:

b. An alkene with a chemical formula of C₁₀H₁₂, that has cis–trans isomers and contains a benzene ring.

Which of the following compounds are capable of cis–trans isomerism?

a. <IMAGE>

b. <IMAGE>

c. <IMAGE>

Why do you suppose small-ring cycloalkenes like cyclohexene do not exist as cis–trans isomers, whereas large ring cycloalkenes like cyclodecene do show isomerism?

Name all unbranched ether and alcohol isomers with formula C₅H₁₂O and write their structural formulas.

Identify the compounds in each of the following pairs as structural isomers or not structural isomers: (11.3)

b. <IMAGE>

Indicate whether each of the following pairs represent structural isomers or the same molecule:

b. <IMAGE>

Identify the following pairs of structures as structural isomers, cis–trans isomers, or the same molecule: (11.5, 11.6)

a. <IMAGE>

Draw the condensed structural formulas for all the possible haloalkane isomers that have four carbon atoms and a bromine. (11.3)

Indicate whether each of the following pairs represent structural isomers or the same molecule:

a. <IMAGE>

What is the difference between a conformational isomer of a compound and a structural isomer of the same compound?

Determine the relationship between each of the pairs of the following compounds. Are they structural isomers (different molecules), conformational isomers (the same molecule), or not related?

(b) <IMAGE> and <IMAGE>

Determine the relationship between each of the pairs of the following compounds. Are they structural isomers (different molecules), conformational isomers (the same molecule), or not related?

(a) <IMAGE> and <IMAGE>

Determine the relationship between each of the pairs of the following compounds. Are they structural isomers (different molecules), conformational isomers (the same molecule), or not related?

(d) <IMAGE> and <IMAGE>

Determine if each of the following cycloalkanes or alkenes can exist as cis–trans stereoisomers. For those that can, draw the two isomers. Label each of the isomers you drew as the cis stereoisomer or the trans stereoisomer.

(b) CH₃CH₂CH₂CH₂CH=CH₂

Alkanes are also referred to as saturated hydrocarbons. Explain the meaning of the term hydrocarbon. Why are alkanes called saturated hydrocarbons?

Draw skeletal structures for each of the following molecules:

(b) cis-1-chloro-3-methylcyclohexane

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) <IMAGE>

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) <IMAGE>

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

(c) <IMAGE>

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

(b) <IMAGE>

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

(c) <IMAGE> and <IMAGE>

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) <IMAGE>

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.

<IMAGE> The retinal molecules