If a hydrocarbon has nine carbon atoms, three double bonds, and one ring, how many hydrogen atoms must it have?

Hint: If you prefer to use a formula, elements of unsaturation = 1/2(2C + 2 - H)

C = number of carbons

H = number of hydrogens

Calculate the number of elements of unsaturation implied by the molecular ­formula C₆H₁₂.

Hint: If you prefer to use a formula, elements of unsaturation = 1/2(2C + 2 - H)

C = number of carbons

H = number of hydrogens

Give five examples of structures with this formula (C₆H₁₂). At least one should contain a ring, and at least one should contain a double bond.

Hint: If you prefer to use a formula, elements of unsaturation = 1/2(2C + 2 - H)

C = number of carbons

H = number of hydrogens

Determine the number of elements of unsaturation in the molecular formula C₄H₆. Give all nine possible structures having this formula. Remember that

a double bond = one element of unsaturation

a ring = one element of unsaturation

a triple bond = two elements of unsaturation

Draw five more compounds of formula C₄H₆NOCl.

For each of the following molecular formulas, determine the number of elements of unsaturation, and draw three examples.

a. C₄H₄Cl₂

b. C₄H₈O

c. C₆H₈O₂

For each of the following molecular formulas, determine the number of elements of unsaturation, and draw three examples. 

d. C₅H₅NO₂

e. C₆H₃NClBr 

Give the systematic (IUPAC) names of the following alkenes.

(a)

(b)

Give the systematic (IUPAC) names of the following alkenes.

(d)

(e)

Give the systematic (IUPAC) names of the following alkenes.

(f)

(g)

1. Determine which of the following compounds show cis-trans isomerism.

2. Draw and name the cis and trans (or Z and E) isomers of those that do.

a. hex-3-ene

b.buta-1,3-diene

1. Determine which of the following compounds show cis-trans isomerism.

2. Draw and name the cis and trans (or Z and E) isomers of those that do.

c. hexa-2,4-diene

d. 3-methylpent-2-ene

1. Determine which of the following compounds show cis-trans isomerism.

2. Draw and name the cis and trans (or Z and E) isomers of those that do.

e. 2,3-dimethylpent-2-ene

f. 3,4-dibromocyclopentene

The following names are all incorrect. Draw the structure represented by the incorrect name (or a consistent structure if the name is ambiguous), and give your drawing the correct name.

a. cis-dimethylpent-2-ene

b. 3-vinylhex-4-ene

For each reaction, decide whether substitution or elimination (or both) is possible, and predict the products you expect. Label the major products.

b. 1-bromo-1-methylcyclohexane + triethylamine(Et₃N:)

The following names are all incorrect. Draw the structure represented by the incorrect name (or a consistent structure if the name is ambiguous), and give your drawing the correct name.

c. 2-methylcyclopentene

d. 6-chlorocyclohexadiene

The following names are all incorrect. Draw the structure represented by the incorrect name (or a consistent structure if the name is ambiguous), and give your drawing the correct name.

e. 2,5-dimethylcyclohexene

Some of the following examples can show geometric isomerism, and some cannot. For the ones that can, draw all the geometric isomers, and assign complete names using the E-Z system.

a. 3-bromo-2-chloropent-2-ene

b. 3-ethylhexa-2,4-diene

Some of the following examples can show geometric isomerism, and some cannot. For the ones that can, draw all the geometric isomers, and assign complete names using the E-Z system.

c. 3-bromo-2-methylhex-3-ene

d. penta-1,3-diene

Some of the following examples can show geometric isomerism, and some cannot. For the ones that can, draw all the geometric isomers, and assign complete names using the E-Z system.

e. 3-ethyl-5-methyloct-3-ene

f. 3,7-dichloroocta-2,5-diene

Some of the following examples can show geometric isomerism, and some cannot. For the ones that can, draw all the geometric isomers, and assign complete names using the E-Z system.

(g)

(h)

Some of the following examples can show geometric isomerism, and some cannot. For the ones that can, draw all the geometric isomers, and assign complete names using the E-Z system.

(i)

How many stereogenic double bonds are in octa-1,3,5-triene? How many stereocenters are there? Draw and name the four stereoisomers of octa-1,3,5-triene.

Draw the six stereoisomers of octa-2,4,6-triene. Explain why there are only six stereoisomers, rather than the eight we might expect for a compound with three stereogenic double bonds.

Teflon-coated frying pans routinely endure temperatures that would cause polyethylene or polypropylene to oxidize and decompose. Decomposition of polyethylene is initiated by free-radical abstraction of a hydrogen atom by O₂. Bond-dissociation energies of C—H bonds are about 400 kJ/mol, and C—F bonds are about 460 kJ/mol. The BDE of the H—OO bond is about 192 kJ/mol, and the F—OO bond is about 63 kJ/mol. Show why Teflon (Figure 7-5) is much more resistant to oxidation than polyethylene is.

For each pair of compounds, predict the one with a higher boiling point. Which compounds have zero dipole moments?

a. cis-1,2-dichloroethene or cis-1,2-dibromoethene

For each pair of compounds, predict the one with a higher boiling point. Which compounds have zero dipole moments?

b. cis- or trans-2,3-dichlorobut-2-ene

For each pair of compounds, predict the one with a higher boiling point. Which compounds have zero dipole moments?

c. cyclohexene or 1,2-dichlorocyclohexene

Use the data in Table 7-2 to predict the energy difference between 2,3-dimethylbut-1-ene and 2,3-dimethylbut-2-ene. Which of these double-bond isomers is more stable?