Chapter 7

The carbon-carbon bond length in ethylene is ________ than the carbon-carbon bond length in ethane, and the HCH bond angle in ethylene is ________ the HCH bond angle in ethane

shorter; larger than

Using Zaitsev's rule, choose the most stable alkene among the following. A) 1,2-dimethylcyclohexene B) 1,6-dimethylcyclohexene C) cis-3,4-dimethylcyclohexene D) They are all of equal stability according to Zaitsev's rule.

1,2-dimethylcyclohexene

Which of the following alkenes has the largest molar heat of hydrogenation (ie, releases the most heat upon hydrogenation)? A) 2,3-dimethyl-2-butene B) 2-methyl-2-butene C) trans-2-butene D) cis-2-butene E) 1-hexene

1-hexene

Which of the following best approximates the CCC bond angle of propene?

120°

Which of the alkyl chlorides listed below undergoes dehydrohalogenation in the presence of a strong base to give pent-2-ene as the only alkene product? A) 1-chloropentane B) 2-chloropentane C) 3-chloropentane D) 1-chloro-2-methylbutane E) 1-chloro-3-methylbutane

3-chloropentane

The compound produced when 3-methylpent-2-ene undergoes hydrogenation in the presence of a platinum catalyst is ________.

3-methylpentane

The steroid testosterone has the molecular formula C19H28O2. Given that there are two P -bond in a molecule of testosterone, how many rings are present in each molecule?

4

Provide an acceptable name for (CH3CH2)2CHCH2CH=CH2.

4-ethylhex-1-ene

The trans isomers of cycloalkenes with rings containing fewer than ________ atoms are unstable at room temperature.

8

What two atomic orbitals or hybrid atomic orbitals overlap to form the C-C π bond in ethylene?

C p + C p

What two atomic orbitals or hybrid atomic orbitals overlap to form the C-C σ bond in ethylene?

C sp2 + C sp2

What two atomic orbitals or hybrid atomic orbitals overlap to form the C-H bond in ethylene?

C sp2 + H s

By what mechanism does cyclohexanol react when treated in sulfuric acid and what compound results?

E1; cyclohexene

Dehydrohalogenation of 2-bromobutane in the presence of a strong base proceeds via which of the following mechanistic pathways?

E2

Dehydrohalogenation of an alkyl halide by treating it with a strong base to yield an alkene product typically occurs by what reaction mechanism?

E2

Provide the structure of the monomer from which PVC or poly(vinyl chloride) is made.

H2C=CHCl

Does the alkene shown below violate Bredt's rule?

No

Which of the following statements applies to the E2 mechanism?

The C-H and C-X bonds that break must be anti.

For which of the following alkenes will cis- and trans- isomers not exist?

a) only

Alkenes ________.

have lower boiling points than alcohols of similar molecular weight

Provide the proper IUPAC name for the alkene shown below. CH2-CHCH2CH2CH2CH3

hex-1-ene

Carbon-carbon single bonds tend to be ________ and ________ than carbon-carbon double bonds.

longer, weaker

Provide the name of the major alkene product that results when (2S,3R)-2,3-dibromopentane is treated with zinc in acetic acid.

(E)-2-pentene

Provide the name of the major alkene product that results when (2S,3S)-2-bromo-3-methylpentane is treated with sodium methoxide in methanol.

(E)-3-methyl-2-pentene

Using Zaitsev's rule, choose the most stable alkene among the following. A) hex-1-ene B) (E)-hex-2-ene C) (Z)-hex-2-ene D) They are all of equal stability according to Zaitsev's rule.

(E)-hex-2-ene

Provide the name of the major alkene product that results when (2R,3R)-2,3-dibromopentane is treated with zinc in acetic acid.

(Z)-2-pentene

Provide the name of the major alkene product that results when (2S,3R)-2-bromo-3-methylpentane is treated with sodium methoxide in methanol.

(Z)-3-methyl-2-pentene

Draw the structure of poly(tetrafluoroethylene) or Teflon.

-[CF2CF2]n-

Draw the structure of polyethylene.

-[CH2CH2]n-

Using Zaitsev's rule, choose the most stable alkene among the following. A) 1-methylcyclohexene B) 3-methylcyclohexene C) 4-methylcyclohexene D) They are all of equal stability according to Zaitsev's rule

1-methylcyclohexene

Provide a series of steps through which 2-methylbutane is converted into 2-methylbut-1-ene?

1. Br2, hn 2. (CH3)3CO-

Provide the reagents necessary for carrying out the transformation of 2-methylheptane to 2-methylhept-1-ene

1. Br2, hν 2. (CH3)3CO-K+, (CH3)3COH

Provide the reagents necessary for carrying out the transformation of 2-methylheptane to 2-methylhept-2-ene.

1. Br2, hν 2. NaOH, acetone

Provide the reagents necessary for carrying out the transformation of cyclopentane to cyclopentene.

1. Br2, hν 2. NaOH, acetone

Consider molecules with the formula C10H16. Which of the following structural features are not possible within this set of molecules?

2 triple bonds

Which of the following alkenes can show geometric isomerism: 2,3-dichloro-2-pentene, 4-chloro-3-ethyl-3-hexene, 3-chloro-2-methyl-2-butene, and 3-chloro-2-methyl-1-butene?

2,3-dichloro-2-pentene

Which of the following alkenes has the smallest molar heat of hydrogenation (ie, releases the least heat upon hydrogenation)? A) 2,3-dimethyl-2-butene B) 2-methyl-2-butene C) trans-2-butene D) cis-2-butene E) 1-hexene

2,3-dimethyl-2-butene

Provide an acceptable name for (CH3)2CHCH=C(CH3)CH2CH3.

2,4-dimethylhex-3-ene

Which of the following alkenes is the major product when 2-bromo-2-methylpentane is treated with potassium tert-butoxide in tert-butanol? A) 2-methylpent-1-ene B) 2-methylpent-2-ene C) (E)-4-methylpent-2-ene D) (Z)-4-methylpent-2-ene E) 4-methylpent-1-ene

2-methylpent-1-ene

Which of the following alkenes is the major product when 2-bromo-2-methylpentane is treated with sodium ethoxide in ethanol? A) 2-methylpent-1-ene B) 2-methylpent-2-ene C) (E)-4-methylpent-2-ene D) (Z)-4-methylpent-2-ene E) 4-methylpent-1-ene

2-methylpent-2-ene

A chemist has isolated a new natural product and determined its molecular formula to be C24H40O4. In hydrogenation experiments the chemist found that each mole of the natural product reacted with two moles of H2. How many rings are present in the structure of the new natural product?

3

Draw the alkene of formula C5H10 which evolves the most heat per mole upon hydrogenation

CH2=CHCH2CH2CH3

Draw all likely alkene products in the following reaction and circle the product you expect to predominate.

No alkene product likely

Consider the constitutional isomers 2-methylbut-1-ene, 2-methylbut-2-ene, and 3-methylbut-1-ene. When each of these alkenes is subjected to catalytic hydrogenation (H2, Pt), a single product results. Which of the following best describes the structural relationship among these products?

The products are identical.

3<1<2

Which sequence ranks the following compounds in order of increasing heat of hydrogenation, ΔHhyd? 1) cis-2-butene 2) 1-butene 3) cyclohexene

Does the alkene shown below violate Bredt's rule?

Yes

What reagent could be used to prepare cyclopentene from trans-1,2-dibromocyclopentane?

Zn/CH3CO2H

What kind of reactive intermediate is present in the mechanism of the following reaction?

allylic radical

In the group shown below, which of the following alcohols is (are) likely to yield a product where skeletal rearrangement has occurred when treated with sulfuric acid? 3-methyl-3-pentanol,3,3-dimethyl-2-butanol,2,2-dimethylcyclohexanol

both 3,3-dimethyl-2-butanol and 2,2-dimethylcyclohexanol

Predict the major product of the reaction shown below. (CH3)3CCH(OH)CH3 →H3PO4,heat→

major product is: 2,3-dimethyl-2-butene

which of the following best describes the relative bond dissociation energies of sigma and pi bonds present in the carbon-carbon double bond of an alkene?

sigma>pi