Reactions of alkenes | Practice Problems, Examples & Solutions

Reactivity of the Carbon-Carbon Double Bond

Introduction to General, Organic and Biochemistry

Four alternatives to the structure of benzene proposed by Kekulé are shown in the text. In this problem, we ask you to propose additional alternatives for compounds with the molecular formula $\mathrm{C}_{6} \mathrm{H}_{6}$ As you think about possible alternatives keep in mind the building blocks available to you. Also keep in mind that carbon must be tetravalent, that is, each carbon must have no more and no fewer than four bonds.
Three- four- , five- , and six-membered rings Carbon-carbon single, double, and triple bonds The possibility for cis$/$trans isomerism for carbon-carbon double bonds

Benzene and Its Derivatives

02:19

Chemistry

Predict products when HBr is added to (a) 1-butene and (b) 2-butene.

Organic Chemistry

01:24

Organic Chemistry

Reaction of 2,3 -dimethyl-1-butene with HBr leads to an alkyl bromide, $\mathrm{C}_{6} \mathrm{H}_{13} \mathrm{Br}$. On treatment of this alkyl bromide with KOH in methanol, elimination of HBr occurs and a hydrocarbon that is isomeric with the starting alkene is formed. What is the structure of this hydrocarbon, and how do you think it is formed from the alkyl bromide?

Alkenes: Structure and Reactivity

Electrophilic Addition to Alkenes

19 Practice Problems

00:34

Biochemistry

Is the conversion of fumarate to malate a redox (electron transfer ) reaction? Give the reason for your answer.

The Citric Acid Cycle

02:02

Introduction to General, Organic and Biochemistry

Draw a structural formula for the product of each alkene addition reaction.

Alkenes and Alkynes

00:52

Organic Chemistry

What stereoisomers are obtained when (S)-3-methyl-1-pentene reacts with $\mathrm{Cl}_{2} ?$

The Reactions of Alkenes • The Stereochemistry of Addition Reactions

Addition of Hydrogen Halides to Alkenes

9 Practice Problems

02:11

Organic Chemistry

a. When HBr adds to a conjugated diene, what is the rate-determining step?
b. When HBr adds to a conjugated diene, what is the product-determining step?

Delocalized Electrons and Their Effect on Stability, $\mathrm{p} K_{\mathrm{a}}$, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene"

01:40

Organic Chemistry

What is the major product obtained from the addition of HBr to the following compound?

Delocalized Electrons and Their Effect on Stability, $\mathrm{p} K_{\mathrm{a}}$, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene"

03:03

Organic Chemistry

a. What five-carbon alkene will form the same product whether it reacts with HBr in the presence of a peroxide or with HBr in the absence of a peroxide?
b. Give three alkenes containing six carbon atoms that form the same product, whether they react with HBr in the presence of a peroxide or with HBr in the absence of a peroxide.

Reactions of Alkenes

Addition of Water: Hydration of Alkenes

4 Practice Problems

00:46

Organic Chemistry

Answer the following questions about the mechanism for the acid-catalyzed hydration of an alkene:
a. How many transition states are there?
b. How many intermediates are there?
c. Which step in the forward direction has the smallest rate constant?

The Reactions of Alkenes • The Stereochemistry of Addition Reactions

06:53

Organic Chemistry

What products are formed from acid-catalyzed hydration of racemic ( $\pm$ )-4-methyl1-hexene? What can you say about the relative amounts of the products? Is the product mixture optically active?

Alkenes: Reactions and Synthesis

02:18

Organic Chemistry

What alkyne gives each set of products after treatment with $O_3$ followed by $H_2O$?

Oxidation and Reduction

Hydration by Oxymercuration–Demercuration

1 Practice Problems

02:53

Organic Chemistry

What products would you expect from oxymercuration-demercuration of the following alkenes?
(a) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}=\mathrm{CH}_{2}$
(b) $\mathrm{CH}_{3}$ $\quad \mathrm{CH}_{3} \mathrm{C}=\mathrm{CHCH}_{2} \mathrm{CH}_{3}$

Alkenes: Reactions and Synthesis

Alkoxymercuration–Demercuration

0 Practice Problems

Hydroboration of Alkenes

6 Practice Problems

01:09

Organic Chemistry

A, a compound with molecular formula $\mathrm{C}_{6} \mathrm{H}_{10},$ contains three methylene units. A reacts with one equivalent of $\mathrm{H}_{2}$ over $\mathrm{Pd} / \mathrm{C}$ to yield $\mathbf{B}$. A reacts with aqueous acid to form a single product, $\mathbf{C},$ and undergoes hydroboration/oxidation to form a pair of enantiomers, $\mathbf{D}$ and $\mathbf{E}$. Ozonolysis of $\mathbf{A}$ followed by reaction with dimethyl sulfide forms $\mathbf{F}$ with molecular formula $\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{O}_{2} .$ Provide structures for $\mathbf{A}-\mathbf{F}$.

The Reactions of Alkenes • The Stereochemistry of Addition Reactions

01:17

Organic Chemistry

What is the major product obtained from hydroboration-oxidation of the following alkenes?
a. 2-methyl-2-butene $\quad$ b. 1 -methylcyclohexene

The Reactions of Alkenes • The Stereochemistry of Addition Reactions

03:21

Organic Chemistry

What product would be obtained from hydroboration-oxidation of the following alkenes?
a. 2 -methyl- 2 -butene
b. 1-methylcyclohexene

Reactions of Alkenes

Addition of Halogens to Alkenes

3 Practice Problems

06:14

Organic Chemistry

Draw the products formed when $CH_3CH_2C= CCH_2CH_3$ is treated with each reagent:
(a) $Br_2 (2 equiv); (b) Cl_2$ (1 equiv).

Alkynes

Addition of Halogen

02:16

Organic Chemistry

Draw the products of each reaction, including stereochemistry.

Alkenes

Halogenation-Addition of Halogen

Formation of Halohydrins

1 Practice Problems

10:13

Organic Chemistry

Draw the products of each reaction and indicate their stereochemistry.

Alkenes

Halohydrin Formation

Catalytic Hydrogenation of Alkenes

14 Practice Problems

03:34

Introduction to General, Organic and Biochemistry

How many moles of $\mathrm{H}_{2}$ are used up in the catalytic hydrogenation of one mole of a triglyceride containing glycerol, palmitic acid, oleic acid, and linoleic acid?

Lipids

02:25

Organic Chemistry

Primary amines can also be prepared by the reaction of an alkyl halide with azide ion, followed by catalytic hydrogenation. What advantage do this method and the Gabriel synthesis have over the synthesis of a primary amine using an alkyl halide and ammonia?

Reactions of Carboxylic Acids and Carboxylic Derivatives

01:05

Organic Chemistry

a. Which is the most stable: 3,4 -dimethyl- 2 -hexene, 2,3 -dimethyl- 2 -hexene, or 4,5 -dimethyl- 2 -hexene?
b. Which compound has the largest heat of hydrogenation?
c. Which compound has the smallest heat of hydrogenation?

Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics

Addition of Carbenes to Alkenes

0 Practice Problems

Epoxidation of Alkenes

5 Practice Problems

01:12

Organic Chemistry

A student added an equivalent of 3,4 -epoxy- 4 -methylcyclohexanol to a solution of methylmagnesium bromide in diethyl ether, and then added dilute hydrochloric acid. He expected that the product would be 1,2 -dimethyl- 1,4 -cyclohexanediol. He did not get any of the expected product. What product did he get?

Organometallic Compounds

04:10

Organic Chemistry

Trans alkenes are converted into their cis isomers and vice versa on epoxidation followed by treatment of the epoxide with triphenylphosphine. Propose a mechanism for the epoxide $\rightarrow$ alkene reaction. (EQUATION CAN'T COPY)

Aldehydes and Ketones: Nucleophilic Addition Reactions

01:21

Organic Chemistry

Dimethyldioxirane (DMDO), whose structure is shown below, is another reagent commonly used for alkene epoxidation. Write a mechanism for the epoxidation of ( $Z$ )- - -butene by DMDO, including a possible transition state structure. What is the by-product of a DMDO epoxidation?

Alcohols and Ethers

Acid-Catalyzed Opening of Epoxides

0 Practice Problems

Syn Dihydroxylation of Alkenes

1 Practice Problems

02:07

Organic Chemistry

Draw the products formed when both cis- and trans-2-butene are treated with $4Os0_4$, followed by
hydrolysis with $NaHS0_3$ $+ H_20$. Explain how these reactions illustrate that syn dihydroxylation is
stereospecific.

Oxidation and Reduction

Dihydroxylation

Oxidative Cleavage of Alkenes

5 Practice Problems

04:02

Organic Chemistry

a. The following product was obtained from the ozonolysis of an alkene followed by treatment with dimethyl sulfide. What is the structure of the alkene?
b. The following products were obtained from the oxidative cleavage of a diene. What is the structure of the diene?
SOLUTION TO 33 a. Because only one product is obtained, the reactant must be a cyclic alkene. Numbering the product shows that the carbonyl groups are at $\mathrm{C}-1$ and $\mathrm{C}-6,$ so the double bond in the alkene must be between $\mathrm{C}-1$ and $\mathrm{C}-6,$.
SOLUTION TO 33 b. The five-carbon product with two carbonyl groups indicates that the diene must contain five carbons flanked by two double bonds.
One of the other two products obtained from ozonolysis has one carbon, and the other has three carbons. Therefore, one carbon must be added to one end of the diene, and three carbons must be added to the other end.

The Reactions of Alkenes • The Stereochemistry of Addition Reactions

06:59

Organic Chemistry

Propose structures for hydrocarbons that give the following products on oxidative cleavage by $\mathrm{KMnO}_{4}$ or $\mathrm{O}_{3}:$
a.(FIGURE CAN'T COPY)
b.(FIGURE CAN'T COPY)
c.(FIGURE CAN'T COPY)
d.(FIGURE CAN'T COPY)
e.(FIGURE CAN'T COPY)

Alkynes: An Introduction to Organic Synthesis

02:42

Organic Chemistry

Using an oxidative cleavage reaction, explain how you would distinguish between the following two isomeric dienes:

Alkenes: Reactions and Synthesis

Polymerization of Alkenes

10 Practice Problems

00:43

Chemistry

Would long-chain hydrocarbons or addition polymers of alkene molecules form liquid crystals? Why or why not?

Modern Materials

00:54

Organic Chemistry

Rank the following groups of monomers from most able to least able to undergo anionic polymerization:

Synthetic Polymers

00:34

Chemistry The Central Science

The polymer Kevlar, a condensation polymer, is used as reinforcement in car tires, strings of archery bows, and as a component of bulletproof vests. Draw the structures of the two monomers that yield Kevlar.

Solids and Modern Materials

Olefin Metathesis

1 Practice Problems

05:29

Organic Chemistry

What products are formed when $cis$-2-pentene undergoes metathesis? Use this reaction to explain
why metathesis of a 1,2-disubstituted alkene (RCH=CHR') is generally not a practical method for
alkene synthesis.

Carbon-Carbon BondForming Reactions in Organic Synthesis

Metathesis

Addition versus elimination

5 Practice Problems

02:03

General Chemistry: Principles and Modern Applications

Write a balanced chemical equation for the reaction that is described and then classify the reaction as
a substitution, an elimination, an addition, or a rearrangement reaction.
(a) 3,3 -dimethylbut-1-ene reacts in acid solution to yield 2,3-dimethylbut-2-ene.
(b) 1 -iodo-2,2-dimethylpropane reacts with water to produce, 2,2 -dimethylpropan- $1-$ ol, and $\mathrm{HI}(\text { aq })$.
(c) 2 -chloro- 2 -methylpropane reacts with $\mathrm{NaOH}(\mathrm{aq})$ to give 2 -methylprop-1-ene, sodium chloride, and water.

Reactions of Organic Compounds

04:35

General Chemistry: Principles and Modern Applications

Describe what is meant by each of the following reaction types, and illustrate with an example: (a) nucleophilic substitution reaction; (b) electrophilic substitution reaction; (c) addition reaction; (d) elimination reaction; (e) rearrangement reaction.

Reactions of Organic Compounds

02:18

Organic Chemistry

Classify each of the following reactions as an addition, elimination, substitution, or rearrangement:
(a) $\mathrm{CH}_{3} \mathrm{Br}+\mathrm{KOH} \rightarrow \mathrm{CH}_{3} \mathrm{OH}+\mathrm{KBr}$
(b) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Br} \rightarrow \mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}+\mathrm{HBr}$
(c) $\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}+\mathrm{H}_{2} \rightarrow \mathrm{CH}_{3} \mathrm{CH}_{3}$

An Overview of Organic Reactions

Hydrohalogenation

0 Practice Problems

Acid-catalyzed hydration

7 Practice Problems

02:29

Introduction to General, Organic and Biochemistry

As we will see in Chapter $16,$ the carbonyl group of aldehydes and ketones reacts with water to form a compound called a hydrate. The hydration of a carbonyl group is catalyzed by acid. Formaldehyde, for example, reacts as shown below. When dissolved in water, formaldehyde exists almost entirely as its hydrate. This aqueous solution is given the name formalin.
The mechanism for this acid-catalyzed hydration is similar to the mechanism for the acid-catalyzed hydration of an alkene to give an alcohol and occurs by the following three steps. Step 1: Add a proton. Step 2: Make a new covalent bond between an electrophile (an electron-seeking species) and a nucleophile (an electron-donating species). Step 3: Take a proton away. Write an equation for each step and show by the use of curved arrows how each of these steps occurs. Show all bond-forming steps and bond-breaking steps.

Alcohols, Ethers, and Thiols

02:23

Introduction to General, Organic and Biochemistry

The mechanism of the acid-catalyzed dehydration of an alcohol to an alkene is the reverse of the acidcatalyzed hydration of an alkene. The dehydration mechanism occurs by the following three steps. Step 1: Add a proton. Step 2: Break a bond to form stable molecules or ions. Step 3: Take away a proton. These three steps are illustrated here by the dehydration of 2 -butanol to give 2 -butene. Use curved arrows to show the flow of electrons in each step; that is, show how each bond-making or bond-breaking step occurs.

Alcohols, Ethers, and Thiols

06:57

Introduction to General, Organic and Biochemistry

Answer true or false.
(a) The two most important reactions of alcohols are their acid-catalyzed dehydration to give alkenes and their oxidation to aldehydes, ketones, and carboxylic acids.
(b) The acidity of alcohols is comparable to that of water.
(c) Water-insoluble alcohols and water-insoluble phenols react with strong bases to give watersoluble salts.
(d) Acid-catalyzed dehydration of cyclohexanol gives cyclohexane.
(e) When the acid-catalyzed dehydration of an alkene can yield isomeric alkenes, the alkene with the greater number of hydrogens on the carbons of the double bond generally predominates.
(f) The acid-catalyzed dehydration of 2-butanol gives predominantly 1-butene.
(g) The oxidation of a primary alcohol gives either an aldehyde or a carboxylic acid depending on experimental conditions.
(h) The oxidation of a secondary alcohol gives a carboxylic acid.
(i) Acetic acid, $\mathrm{CH}_{3} \mathrm{COOH}$, can be prepared from ethylene, $\mathrm{CH}_{2}=\mathrm{CH}_{2}$, by treatment of ethylene with $\mathrm{H}_{2} \mathrm{O} / \mathrm{H}_{2} \mathrm{SO}_{4}$, followed by treatment with $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7} / \mathrm{H}_{2} \mathrm{SO}_{4}$
(j) Treatment of propene, $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}$, with $\mathrm{H}_{2} \mathrm{O} /$
$\mathrm{H}_{2} \mathrm{SO}_{4}$ followed by treatment with $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{2} / \mathrm{H}_{2} \mathrm{SO}_{4}$
gives propanoic acid, $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH}$

Alcohols, Ethers, and Thiols

Oxymercuration-demercuration

0 Practice Problems

Hydroboration-oxidation

7 Practice Problems

05:59

Organic Chemistry

Specify the appropriate alkene and reagents for synthesis of each of the following alcohols by hydroboration-oxidation.
(EQUATION CAN'T COPY)

Alkenes and Alkynes II

05:39

Organic Chemistry

Which alcohols can be prepared as a single product by hydroboration-oxidation of an alkene? Which alcohols can be prepared as a single product by the acid-catalyzed addition of H2O to an alkene?

Alkenes

03:16

Organic Chemistry

Draw the products formed when the following alkynes are treated with each set of reagents:
[1) $H_20, H_2S0_4, HgS0_4; or [2] R_2BH$ followed by $H_20_2, ^-OH$.

Alkynes

Hydroboration-Oxidation

Anti versus syn additions

1 Practice Problems