1 Lecture 4 Alcohols, Phenols, and Thiols Alcohols, Phenols, and Thiols Copyright © 2007 by Pearson...

1

Lecture 4 Alcohols, Phenols, and Thiols

Alcohols, Phenols, and Thiols

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

2

Midterm II Outcome

0%

5%

10%

15%

20%

25%

30%

> 90 80-90 70-79 50-70 < 50

Score on Test

% S

tuden

t

Class Average: 75High Score: 103Low Score: 32

3

Alcohols and Phenols

An alcohol contains A hydroxyl group

(—OH) attached to a carbon chain.

A phenol contains A hydroxyl group

(—OH) attached to a benzene ring.


4

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

5

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

6

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

7

More Names of Alcohols

In 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-

hexanol6 5 4 3 2 1

8

Some Typical Alcohols

OH |“rubbing alcohol” CH3—CH—CH3

2-propanol (isopropyl alcohol)

antifreeze HO—CH2—CH2—OH

1,2-ethanediol (ethylene glycol) OH

| glycerolHO—CH2—CH—CH2—OH

1,2,3-propanetriol


9

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

10

Write the structure of the following:

A. 3-pentanol

B. ethyl alcohol

C. 3-methylcyclohexanol

Learning Check

11

Naming Phenols

To name a phenol with two substituents, Assign C-1 to the carbon attached to the –OH. Number the ring to give the lowest numbers. Use prefixes o, m, and p for common names.

OH

Cl

OHOH

Br

Phenol 3-chlorophenol 4-bromophenol (m-chlorophenol) (p-bromophenol)

12

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

13

Derivatives of Phenol

Compounds of phenol are the active ingredients in the essential oils of cloves, vanilla, nutmeg, and mint.

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

14

Write the structure of each of the following:

A. 3-pentanol

B. ethyl alcohol

C. p-methylphenol

Learning Check

15

Thiols

Thiols Are carbon compounds

that contain a –SH group.

Are named in the IUPAC system by adding thiol to the alkane name of the longest carbon chain.

16

In thiols with long carbon chains, the chain is numbered to locate the –SH group.

CH3—CH2—CH2—SH 1-propanethiol

SH |

CH3—CH—CH3 2-propanethiol

Naming Thiols

17

Thiols

Thiols Often have

strong odors. Are used to

detect gas leaks. Are found in

onions, oysters, and garlic.


18

Learning Check

Draw the structure of each compound.

A. 2-butanethiol

B. 2-methyl-1-butanol

19

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

20

Pause: Group Activity

Do the following problems on ALE 4 Problem # 1, parts A to F Problem # 2, parts A to D

21

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

dimethyl ether ethyl methyl ether

22

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—CH3

1 2 3

Numbering the longer alkane gives

1-methoxypropane

23

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

24

MTBE

Methyl 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.

25

Learning Check

Draw the structure of each compound.

A. diethyl ether

B. ethyl methyl ether

C. 2-methoxybutane

26

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

27

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”)

28

Learning Check

Name each of the following:

1.

2. O

O

OCH3

29


Do the following problems on ALE 4 Problem # 1, parts G to I Problem # 2, parts E to F

30

Lecture 4

13.3

Physical Properties of Alcohols,

Phenols, and Ethers


31

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.


32

Boiling Points of Ethers

Ethers Have an O atom, but

no H is attached. Cannot form hydrogen

bonds between ether molecules.


33

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.


34

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

35

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+

36

Learning Check

Which compound would have the higher boiling

point? Explain.

ethyl methyl ether or 1-propanol

37

Learning Check

Which compound would be more soluble in water?

Explain.

ethanol or 2-pentanol

38


Do the following problems on ALE 4 Problem # 3 Problem # 4

39

Lecture 4

13.4

Reactions of Alcohols and Thiols


40

Combustion of Alcohols

Combustion is the reaction of an alcohol

with O2 to produce CO2 and H2O.

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


41

Dehydration of an alcohol occurs When heated with an acid catalyst. With the loss of —H and —OH from adjacent carbon

atoms. H OH

| | H+, heatH—C—C—H H—C=C—H + H2O

| | | | H H H H

alcohol alkene

Dehydration of Alcohols

42

Learning Check

Write the equations for the reactions when

2-propanol undergoes:

1. combustion

2. dehydration

43

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

44

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.

45

Oxidation and Reduction


46

When a primary alcohol is oxidized [O], One H is removed from the –OH. Another H is removed from the carbon bonded to the OH. An aldehyde is produced.

[O] Primary alcohol Aldehyde

OH O | [O] ||

CH3—C—H CH3—C—H + H2O |

H Ethanol Ethanal (ethyl alcohol) (acetaldehyde)

Oxidation of Primary (1) Alcohols

47

Oxidation of Secondary (2) AlcoholsWhen a secondary alcohol is oxidized [O], One H is removed from the –OH. Another H is removed from the carbon bonded to the OH. A ketone is produced. [O] secondary alcohol ketone OH O

│ [O] ║ CH3—C—CH3 CH3—C—CH3 + H2O

│ H

2-propanol (isopropyl alcohol) 2-propanone(dimethyl ketone, “acetone”)

48

Oxidation of Tertiary (3)Alcohols

Tertiary alcohols do not readily oxidize. [O]

Tertiary alcohol no reaction OH │ [O]

CH3─C─CH3 no product │ CH3 no H on the C-OH to oxidize

2-methyl-2-propanol

49

Select the compound that would result for each reaction

of CH3—CH2—CH2—OH.

O

||1) CH3—CH=CH2 2) CO2 + H2O 3) CH3—CH2—C—H

A. H+, heat

B. [O]

C. O2, heat

Learning Check

50

Oxidation of Ethanol in the Body

In the body, Ethanol is oxidized by enzymes in the liver. Aldehyde product impairs coordination. O O ║ ║

CH3─CH2─OH CH3─C─H CH3─C─OH ethyl alcohol acetaldehyde acetic acid

2CO2 + H2O

51

Ethanol Acts as a depressant. Kills or disables more

people than any other drug. Is metabolized at a rate of

12-15 mg/dL per hour by a social drinker.

Is metabolized at a rate of 30 mg/dL per hour by an alcoholic.

Ethanol CH3─CH2─OH


52

Effect of Alcohol on the Body

TABLE 13.2


53

Learning Check

Select the product for the oxidation of OH │ [O]

CH3—CH—CH2—CH3

O ║

1) CH3—CH=CH—CH3 2) CH3—C—CH2 —CH3

OH │

3) CO2 + H2O 4) CH3—CH—CH2—CH3

54

Oxidation of Thiols

When thiols undergo oxidation, An H atom is lost from each of two –SH groups. The product is a disulfide.

[O]

CH3—SH + HS—CH3 CH3—S—S—CH3 + H2O

55


Do the following problems on ALE 4 Problem # 5

1 Lecture 4 Alcohols, Phenols, and Thiols Alcohols, Phenols, and Thiols Copyright © 2007 by Pearson...

Documents

Transcript of 1 Lecture 4 Alcohols, Phenols, and Thiols Alcohols, Phenols, and Thiols Copyright © 2007 by Pearson...