Chapter 13 Alcohols, Phenols, and Thiols - Alcohol… · More Names of Alcohols In IUPAC names for...

Chapter 13 Alcohols, Phenols,

and Thiols

13.1

Alcohols, Phenols, and Thiols

Copyright © 2007 by Pearson Education, Inc.

Publishing as Benjamin Cummings

Alcohols and PhenolsAn alcohol contains

• A hydroxyl group

(—OH) attached to

a carbon chain.

A phenol contains

• A hydroxyl group

(—OH) attached to

a benzene ring. Copyright © 2007 by Pearson Education, Inc.


Alcohols are classified

• By the number of alkyl groups attached to the carbon bonded

to the hydroxyl.

• As primary (1°), secondary (2°), or tertiary (3°).

Primary (1º) Secondary (2º) Tertiary (3º)

1 group 2 groups 3 groups

H CH3 CH3

| | |

CH3—C—OH CH3—C—OH CH3—C—OH| | |H H CH3

Classification of Alcohols

Classify each alcohol as

(P) primary, (S) secondary, or (T) tertiary.OH|

1. CH3—CH—CH2—CH3

2. CH3—CH2—CH2—OH

OH |

3. CH3—CH2—C—CH2—CH3|

CH3

Learning Check

OH|

1. CH3—CH—CH2—CH3 (S) secondary

2. CH3—CH2—CH2—OH (P) primary

OH |

3. CH3—CH2—C—CH2—CH3 (T) tertiaryCH3

Solution

Naming Alcohols

The names of alcohols

• In the IUPAC system replace -e of alkane name with -ol.

• that are common names use the name of the alkyl group

followed by alcohol.

Formula IUPAC Common Name

CH4 methane

CH3─OH methanol methyl alcohol

CH3─CH3 ethane

CH3─CH2─OH ethanol ethyl alcohol

More Names of AlcoholsIn IUPAC names for longer carbon chains, the chain is

numbered from the end nearest the ─OH group.

CH3─CH2─CH2─OH 1-propanol

OH│

CH3─CH─CH2─CH3 2-butanol

CH3 OH│ │

CH3─CH─CH2─CH2─CH─CH3 5-methyl-2-hexanol

6 5 4 3 2 1

Some Typical AlcoholsOH|

“rubbing alcohol” CH3—CH—CH3

2-propanol (isopropyl alcohol)

antifreeze HO—CH2—CH2—OH

1,2-ethanediol (ethylene glycol)

OH

|

glycerol HO—CH2—CH—CH2—

OH

1,2,3-propanetriol



Learning Check

Give the IUPAC name for each of the following:

1. CH3—CH2—CH2—CH2—OH

OH CH3

| |

2. CH3—CH—CH—CH2—CH3

3.

OH

Solution1. CH3—CH2—CH2—CH2—OH 1-butanol

OH CH3

| |

2. CH3—CH—CH—CH2—CH3 3-methyl-2-pentanol

3. cyclopentanol OH

Write the structure of the following:

A. 3-pentanol

B. ethyl alcohol

C. 3-methylcyclohexanol

Learning Check

SolutionWrite the structure of the following:

A. 3-pentanol OH

|

CH3—CH2—CH—CH2—CH3

B. ethyl alcohol CH3 —CH2 —OH

C. 3-methylcyclohexanol

CH3

OH

Phenols in Medicine

Phenol

• Is the IUPAC name for benzene with a

hydroxyl group.

• Is used in antiseptics and disinfectants.

phenol resorcinol 4-hexylresorcinol

OH

OH

CH2CH2CH2CH2CH2CH3

OH OH

OH

Derivatives of Phenol• Compounds of phenol are the active ingredients in

the essential oils of cloves, vanilla, nutmeg, and mint.



Learning Check

Name each of the following compounds:

OH

|

A. CH3—CH2 —CH—CH3

CH3

|

B. CH3—CH2—CH—CH2—CH2—OH

C. CH3—CH2—CH2—SH

Solution

Name each of the following compounds:

OH|

A. CH3—CH2 —CH—CH3 2-butanolCH3

| B. CH3—CH2—CH—CH2—CH2—OH

3-methyl-1-pentanol

C. CH3—CH2—CH2—SH1-propanethiol


Ethers, and Thiols

13.2

Ethers

Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings

Ethers

Ethers

• Contain an ─O─ between two carbon groups.

• That are simple are named by listing the alkyl names in alphabetical order followed by ether

CH3─O─CH3 CH3─CH2─O─CH3

IUPAC Names for Ethers

• In the IUPAC system, the shorter alkyl group and the oxygen are named as an alkoxy group attached to the longer alkane.

methoxy propane

CH3—O—CH2—CH2—CH31 2 3

• Numbering the longer alkane gives

1-methoxypropane

Ethers as Anesthetics

Anesthetics

• Inhibit pain signals to the brain.

• Such as ethyl ether CH3─CH2─O─CH2─CH3 were used for

over a century, but caused nausea and were flammable.

• Developed by 1960s were nonflammable.

Cl F F Cl F H

│ │ │ │ │ │H─C─C─O─C─H H─C─C─O─C─H

│ │ │ │ │ │F F F H F H

Ethane(enflurane) Penthrane

MTBEMethyl tert-butyl ether

CH3

│CH3─O─C─CH3

│CH3

• Is one of the most produced organic chemicals.

• Is a fuel additive

• Is used to improve gasoline combustion.

• Use is questioned since the discovery that MTBE has

contaminated water supplies.

Learning Check

Draw the structure of each compound.

A. diethyl ether

B. ethyl methyl ether

C. 2-methoxybutane

Solution

Draw the structure of each compound.

A. diethyl etherCH3—CH2—O—CH2—CH3

B. ethyl methyl ether CH3—CH2—O—CH3

C. 2-methoxybutane

O—CH3

|CH3—CH—CH2—CH3

Cyclic Ethers

A cyclic ether

• Contains an O atom in a carbon ring.

• Is called a heterocyclic compound.

• Typically has 5 (furan) or 6 atoms (pyran) in the ring.

O O O

furan tetrahydrofuran pyran 1,4-dioxane

O

O

Dioxins

Dioxins are

• A group of ethers that are highly toxic.

• Formed during forest fires and as industrial by-products.

• Often carcinogenic.

Cl

Cl Cl

OCH2 OHC

O

Cl

Cl

O

O

Cl

Cl

2,4,5-trichlorophenoxyacetic acid 2,3,7,8-tetrachlorodibenzodioxin

(2,4,5-T; agent orange) (TTCC, “dioxin”)

Learning Check

Name each of the following:

1.

2.

O

O

OCH3

Solution

1. methoxy cyclopentane

(cyclopentyl methyl ether)

2. 1,4-dioxaneO

O

OCH3

Chapter 13 Alcohols, Phenols, Ethers,

and Thiols

13.3 Physical Properties of Alcohols,

Phenols, and Ethers



Boiling Points of Alcohols

Alcohols

• Contain a strongly electronegative O in the OH groups.

• Form hydrogen bonds between alcohol molecules.

• Have higher boiling points than alkanes and ethers of similar mass.



Boiling Points of Ethers

Ethers

• Have an O atom, but no H is attached.

• Cannot form hydrogen bonds between ether molecules.

• Have boiling points similar to alkanes of similar mass.



Solubility of Alcohols and

Ethers in Water• Alcohols and ethers are more soluble in water than alkanes

because the oxygen atom hydrogen bonds with water.

• Alcohols with 1-4 C atoms are soluble, but alcohols with 5

or more C atoms are not.

Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

Comparing Solubility and Boiling

Points

Compound Molar Boiling Soluble

Mass Point (°C) in Water?

Alkane CH3─CH2─CH3 44 -42 No

Ether CH3─O─CH3 46 -23 Yes

Alcohol CH3─CH2─OH 46 78 Yes

Solubility of Phenol

Phenol

• Is soluble in water.

• Has a hydroxyl group that ionizes slightly (weak

acid).

• Is corrosive and irritating to the skin.OH O-

+ H2O + H3O+

Learning Check

Which compound would have the higher

boiling point? Explain.

ethyl methyl ether or 1-propanol

Solution

1-propanol would have the higher boiling

point because an alcohol can form hydrogen

bonds, but the ether cannot.

Learning Check

Which compound would be more soluble in

water?

Explain.

ethanol or 2-pentanol

Solution

Ethanol. An alcohol with two carbons in its

carbon chain is more soluble than one with

5 carbons. The longer alkyl chain

diminishes the effect of the –OH group.


Ethers, and Thiols

Reactions of Alcohols and Thiols



Combustion of Alcohols

Combustion is the reaction of an alcohol

with O2 to produce CO2 and H2O.

2CH3OH + 3O2 2CO2 + 4H2O + Heat



Dehydration of an alcohol occurs

• When heated with an acid catalyst.

• With the loss of —H and —OH from adjacentcarbon atoms.

H OH| | H+, heat

H—C—C—H H—C=C—H + H2O| | | |H H H H

alcohol alkene

Dehydration of Alcohols

Learning Check

Write the equations for the reactions when

2-propanol undergoes:

1. combustion

2. dehydration

Solution

OH

│CH3─CH─CH3 = 2-propanol = C3H8O

1. combustion

2C3H8O + 9O2 6CO2 + 8H2O

2. dehydration

OH

│ H+

CH3─CH─CH3 CH3─CH=CH2 + H2O

Formation of Ethers

• Ethers form when dehydration takes place at low temperature.

H+

CH3—OH + HO—CH3 CH3—O—CH3 + H2O

two methanol dimethyl ether

Oxidation and Reduction

In the oxidation of an organic compound

• There is an increase in the number of C—O bonds.

• There is a loss of H.

In the reduction of an organic compound

• There is an decrease in the number of C—O bonds.

• There is a gain of H.

Oxidation and Reduction

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Chapter 13 Alcohols, Phenols, and Thiols - Alcohol… · More Names of Alcohols In IUPAC names for...

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