1 Chapter 12 Organic Compounds w/ Oxygen & Sulfur 12.1 Alcohols, Phenols, and Thiols Copyright ©...

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Chapter 12 Organic Compounds w/ Oxygen & Sulfur

12.1

Alcohols, Phenols, and Thiols

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

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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.


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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

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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

5

OH |

1. CH3—CH—CH2—CH3 (S) secondary

2. CH3—CH2—CH2—OH (P) primary

OH |

3. CH3—CH2—C—CH2—CH3 (T) tertiary |

CH3

Solution

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 IUPACCommon Name

CH4 methane

CH3─OH methanol methyl alcohol

CH3─CH3 ethane

CH3─CH2─OH ethanol ethyl alcohol

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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

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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


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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

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Solution

1. CH3—CH2—CH2—CH2—OH 1-butanol

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

3. cyclopentanol OH

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Write the structure of the following:

A. 3-pentanol

B. ethyl alcohol

C. 3-methylcyclohexanol

Learning Check

12

Solution

Write 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

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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)

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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

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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

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Write the structure of each of the following:

A. 3-pentanol

B. ethyl alcohol

C. p-methylphenol

Learning Check

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Solution

Write the structure of each of the following:A. 3-pentanol OH

|CH3—CH2—CH—CH2—CH3

B. ethyl alcohol CH3—CH2—OH

C. p-methylphenol OH

CH3

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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.

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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

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Thiols

Thiols Often have

strong odors. Are used to

detect gas leaks. Are found in

onions, oysters, and garlic.


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Learning Check

Draw the structure of each compound.

A. 2-butanethiol

B. 2-methyl-1-butanol

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Solution

Draw the structure of each compound.A. 2-butanethiol

SH|

CH3—CH—CH2—CH3

B. 2-methyl-1-butanol

CH3

| HO—CH2—CH—CH2—CH3

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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

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Solution

Name each of the following compounds:

OH | A. CH3—CH2 —CH—CH3 2-butanol

CH3

| B. CH3—CH2—CH—CH2—CH2—OH

3-methyl-1-pentanol

C. CH3—CH2—CH2—SH

1-propanethiol

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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

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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

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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

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Learning Check

Draw the structure of each compound.

A. diethyl ether

B. ethyl methyl ether

C. 2-methoxybutane

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Solution

Draw the structure of each compound.A. diethyl ether

CH3—CH2—O—CH2—CH3

B. ethyl methyl ether CH3—CH2—O—CH3

C. 2-methoxybutane

O—CH3

| CH3—CH—CH2—CH3

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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”)

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Learning Check

Name each of the following:

1. O

CH3

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Solution

1. methoxy cyclopentane

(cyclopentyl methyl ether)O

CH3

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12.2

Physical Properties of Alcohols,

Phenols, and Ethers


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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.


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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.


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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.


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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

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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+

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Learning Check

Which compound would have the higher boiling

point? Explain.

ethyl methyl ether or 1-propanol

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Solution

1-propanol would have the higher boiling point because

an alcohol can form hydrogen bonds, but the ether

cannot.

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Learning Check

Which compound would be more soluble in water?

Explain.

ethanol or 2-pentanol

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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.

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12.3

Reactions of Alcohols and Thiols


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Combustion of Alcohols

Combustion is the reaction of an alcohol

with O2 to produce CO2 and H2O.

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


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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

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Learning Check

Write the equations for the reactions when

2-propanol undergoes:

1. combustion

2. dehydration

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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

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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.

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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

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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”)

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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

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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

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CH3—CH2—CH2—OH

A. H+, heat 1) CH3—CH=CH2

O ||

B. [O] 3) CH3—CH2—C—H

C. O2, heat 2) CO2 + H2O

Solution

57

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

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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


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Effect of Alcohol on the Body

TABLE 13.2


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Learning Check

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


O ║

1) CH3—CH=CH—CH3 2) CH3—C—CH2 —CH3

OH │

3) CO2 + H2O 4) CH3—CH—CH2—CH3

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Solution

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


O ║

2) CH3—C—CH2—CH3

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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

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12.4

Aldehydes and Ketones


64

Carbonyl Group in Aldehydes and Ketones

A carbonyl group In an aldehyde is

attached to at least one H atom.

In a ketone is attached to two carbon groups.

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Naming Aldehydes

An aldehyde Has an IUPAC name in which the -e in the alkane

name is changed to -al. Has a common name for the first four aldehydes that

use the prefixes form (1C), acet (2C), propion (3C), and butyr (4C), followed by aldehyde.

O O O

║ ║ ║

H−C−H CH3−C−H CH3−CH2−C−H

methanal ethanal propanal

(formaldehyde) (acetaldehyde) (propionaldehyde)

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Naming Aldehydes


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Aldehydes in Flavorings

Several naturally occurring aldehydes are used as flavorings for foods and fragrances.

H

O

C

H

O

CCH=CH

Benzaldehyde(almonds)

Cinnamaldehyde (cinnamon)


68

Naming KetonesKetones are named In the IUPAC system by replacing the -e in the alkane

name with one. The carbonyl carbon is indicated by a number.

With a common name by indicating the alkyl groups attached to the carbonyl group in alphabetical order

followed by ketone.

O O

║ ║

CH3−C−CH3 CH3−C−CH2−CH3

propanone 2-butanone

(dimethyl ketone) (ethyl methyl ketone)

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Ketones in Common Use

Nail polish remover, Solvent

Propanone, Dimethylketone, Acetone

Butter flavoring


70

Classify each as 1) aldehyde or 2) ketone. O O

|| ||A. CH3—CH2—C—CH3 B. CH3—C—H

CH3 O | ||

C. CH3—C—CH2—C—H D. | CH3

Learning Check

O

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A. 2) ketone

B. 1) aldehyde

C. 1) aldehyde

D. 2) ketone

Solution

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Learning Check

Classify each as an aldehyde (1), ketone (2), alcohol (3),or ether (4). O ║ A. CH3─CH2─C─CH3 B. CH3─O─CH3

CH3 O OH

│ ║ │C. CH3─C─CH2─C─H D. CH3─CH─CH3

│ CH3

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Solution

Classify each as an aldehyde (1), ketone (2),

alcohol (3), or ether (4).

O ║ A. CH3─CH2─C─CH3 B. CH3─O─CH3

(2) ketone (4) ether CH3 O OH

│ ║ │C. CH3─C─CH2─C─H D. CH3─CH─CH3

│ CH3

(1) aldehyde (3) alcohol

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Learning Check

Name each of the following: O ║1. CH3─CH2─CH2─CH2─C─H

O

║ 2. Cl─CH2─CH2─C─H O ║ 3. CH3─CH2─C─CH3

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Solution

O ║

1. CH3─CH2─CH2─CH2─C─H pentanal

O ║

2. Cl─CH2─CH2─C─H 3-chloropropanal

O ║

3. CH3─CH2─C─CH3 2-butanone;

ethyl methyl ketone

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Name the following compounds. O

||A. CH3—CH2—CH2—C—CH3 B.

CH3 O

| ||C. CH3—C—CH2—C—H

| CH3

Learning Check

O

77

A. 2-pentanone; methyl propyl ketone

B. cyclohexanone

C, 3,3-dimethylbutanal

Solution

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Learning Check

Draw the structural formulas for each:

A. 4-methylpentanal

B. 2,3-dichloropropanal

C. 3-methyl-2-butanone

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Solution

CH3 O │ ║

A. 4-methylpentanal CH3─CH─CH2─CH2─C─H

Cl O │ ║

B. 2,3-dichloropropanal Cl─CH2─CH─C─H

CH3 O │ ║

C. 3-methyl-2-butanone CH3─CH─C─CH3

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12.5

Properties


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Polar Carbonyl Group

The polar carbonyl group Provides dipole-dipole interactions.

+ - + -

C=O C=O

Does not have H on the oxygen atom. Cannot form hydrogen bonds.

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Boiling Points

Aldehydes and ketones have Polar carbonyl groups (C=O).

+ -

C=O Attractions between polar groups.

+ - + -

C=O C=O Higher boiling points than alkanes and ethers of

similar mass. Lower boiling points than alcohols of similar mass.

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Comparison of Boiling Points

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Aldehydes and ketones have Higher boiling points than alkanes and ethers of

similar mass. Lower boiling points than alcohols of similar mass.

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Learning Check

Select the compound in each pair that would have the

Higher boiling point.

A. CH3—CH2—CH3 or CH3—CH2—OH

B.

C. CH3—CH2—OH or CH3—O—CH3

or

O

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Solution

A. CH3—CH2—OH

B.

C. CH3—CH2—OH

O

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Solubility in Water

The electronegative O atom of the carbonyl group in aldehydes and ketones forms hydrogen bonds with water.


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Learning Check

Indicate if each is soluble or insoluble in water.A. CH3—CH2—CH3

B. CH3—CH2—OH O

||C. CH3—CH2—CH2—C—H

O ||

D. CH3—C—CH3

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Solution

A. CH3—CH2—CH3 insoluble

B. CH3—CH2—OH soluble O ||

C. CH3—CH2—CH2—C—H soluble

O ||

D. CH3—C—CH3 soluble

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90

Oxidation

Aldehydes are easily oxidized to carboxylic acids. O O

|| [O] || CH3—C—H CH3—C—OH Acetaldehyde Acetic acid

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Tollens’ Test

Tollens’ reagent, which contains Ag+, oxidizes aldehydes, but not ketones.

Ag+ is reduced to metallic Ag, which appears as a “mirror” in the test tube.


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Benedict’s Test

In the Benedict’s Test,

Cu2+ reacts with aldehydes that have an adjacent OH group.

Aldehydes are oxidized to carboxylic acids.

Cu2+ is reduced to give Cu2O(s).


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Learning Check

Write the structure and name of the oxidized product

when each is mixed with Tollens’ reagent.

1. butanal

2. acetaldehyde

3. ethyl methyl ketone

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Solution

1. butanal O ||

CH3—CH2—CH2—C—OH butanoic acid

2. acetaldehyde O ||

CH3—C—OH acetic acid

3. ethyl methyl ketone None. Ketones are notoxidized by Tollen’s reagent.

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Addition Reactions

| + - + - | —C=O + X—Y —C—O—X

| Y

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Chiral Molecules


97

Chiral Compounds

Chiral compounds Have the same number of atoms

arranged differently in space. Have one or more chiral carbon

atoms bonded to four different groups.

Are mirror images like your hands. Try to superimpose your thumbs, palms, back of hands, and little fingers. Copyright © 2007 by Pearson Education, Inc.

Publishing as Benjamin Cummings

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Mirror Images

The mirror images of Chiral compounds cannot be superimposed. Two compounds of bromochloroiodomethane can align

the H and I atoms, which places the Cl and Br atoms on opposite sides.

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

99

Achiral Structures are Superimposable

When the mirror image of an achiral structure is rotated, the structure can be aligned with the initial structure. Thus this mirror image is superimposable.


100

Some Everyday Chiral and Achiral Objects

101

Enantiomers

Have same mp, bp, same chemistry

Except: reaction with other chiral molecules

102

Smell:Smell:S-(+)-carvoneS-(+)-carvone

Caraway(Dill)(Manderine Orange Peel)

Caraway(Dill)(Manderine Orange Peel)

R-(-)-carvoneR-(-)-carvone

SpearmintSpearmint

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Have same mp, bp, same chemistry

Except: reaction with other chiral molecules

Enantiomers

•Except: rotation of plane of polarized light

104

Learning Check

Identify each as a chiral or achiral compound.

A

CH2CH3

H CH3

Cl

C

B

H

H CH3

Cl

C

C

Br

H CH3

Cl

C

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Solution

Identify each as a chiral or achiral compound.

chiral achiral chiral

A

CH2CH3

H CH3

Cl

C

B

H

H CH3

Cl

C

C

Br

H CH3

Cl

C

106

Fischer Projections

A Fischer projection

Is a 2-dimensional representation of a 3-dimensional molecule.

Places the most oxidized group at the top.

Uses vertical lines in place of dashes for bonds that go back.

Uses horizontal lines in place of wedges for bonds that come forward.

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Drawing Fischer Projections


108

D and L Notations

By convention, the letter L is assigned to the structure with the —OH on the left.

The letter D is assigned to the structure with the —OH on the right.


109

Learning Check

Indicate whether each pair is a mirror image that

cannot be superimposed.

B.

A.

and

and

Br

CH3 H

CH2OH

C

H

CH3 H

Cl

C

Br

H CH3

CH2OH

C

H

H CH3

Cl

C

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Solution

Indicate whether each pair is a mirror image that

cannot be superimposed

Yes

No

B.

A.

and

and

Br

CH3 H

CH2OH

C

H

CH3 H

Cl

C

Br

H CH3

CH2OH

C

H

H CH3

Cl

C

1 Chapter 12 Organic Compounds w/ Oxygen & Sulfur 12.1 Alcohols, Phenols, and Thiols Copyright ©...

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Transcript of 1 Chapter 12 Organic Compounds w/ Oxygen & Sulfur 12.1 Alcohols, Phenols, and Thiols Copyright ©...