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Organic ChemistryChapter 24b-c

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Aromatic Hydrocarbons

C

CC

CC

C

H

H

H

H

H

H

C

CC

CC

C

H

H

H

H

H

H

Electron micrographof benzene

resonance structure ?

delocalized molecular orbitals

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Other Representations of Benzene

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Aromatic Compound Nomenclature

CH2CH3

ethylbenzene

Cl

chlorobenzene

NH2

aminobenzene

NO2

nitrobenzene

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3

4

5

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Br

Br

1,2-dibromobenzene

Br

Br

1,3-dibromobenzene

o-dibromobenzene m-dibromobenzene

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Aromatic Compound Nomenclature

phenyl group

benzene minus one hydrogen

CH3 – CH – CH3

2-phenylpropane

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Aromatic Compound Reactions

H

H

H

H

H

H

Br

H

H

H

H

H

+ HBr+ Br2

FeBr3

catalyst

H

H

H

H

H

H

CH2CH3

H

H

H

H

H

+ HCl+ CH3CH2ClAlCl3

catalyst

Substitution reaction (atom or group of atoms replaces a H)

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Polycyclic Aromatic Hydrocarbonsbenzene rings fused together

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Functional Group Chemistry

Alcohols contain the hydroxyl functional group and have the general formula R−OH.

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C6H12O6 (aq) 2CH3CH2OH (aq) + 2CO2 (g)enzyme

CH2 CH2 (g) + H2O (g) CH3CH2OH (g)H2SO4

Biological production of ethanol

Commercial production of ethanol

Metabolic oxidation of ethanol

CH3CH2OH CH3CHO + H2

alcohol dehydrogenase

acetaldehyde

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Functional Group Chemistry

Ethers have the general formula R−O−R′.

CH3OH + HOCH3 CH3OCH3 + H2OH2SO4

catalyst

Condensation Reaction

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Functional Group Chemistry

Aldehydes and Ketones contain the carbonyl ( ) functional group.

O

C

R C H

O

• aldehydes have the general formula

R C R′

O

• ketones have the general formula

H C H

O

H C

O

CH3 C

O

CH3H3C

formaldehyde acetaldehyde acetone

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Functional Group Chemistry

Carboxylic acids contain the carboxyl ( −COOH ) functional group.

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• Generally weak acids• React with alcohols to form esters

• Neutralization

• Production of acid halides (intermediates in syntheses)

Properties and Reactions of Carboxylic Acids

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Functional Group Chemistry

Esters have the general formula R′COOR, where R is a hydrocarbon group.

Hydrolysis

Alkaline hydrolysis (saponification)

Characteristic odors and flavors

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Functional Group Chemistry

Amines are organic bases with the general formula R3N (RNH2).

CH3NH2 + H2O RNH3+ + OH-

CH3CH2NH2 + HCl CH3CH2NH3+Cl-

Neutralization

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Some Aromatic Amines

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Example

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24.5

Cholesterol is a major component of gallstones, and it is believed that the cholesterol level in the blood is a contributing factor in certain types of heart disease. From the following structure of the compound, predict its reaction with (a) Br2, (b) H2 (in the presence of a Pt catalyst), (c) CH3COOH.

HO

CH3

CH3C8H17

Example

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24.5

Strategy To predict the type of reactions a molecule mayundergo, we must first identify the functional groups present (see Table 24.4).

Solution There are two functional groups in cholesterol: thehydroxyl group and the carbon-carbon double bond.

(a)The reaction with bromine results in the addition of bromineto the double-bonded carbons, which become single-bonded.

HO

CH3

CH3C8H17

HO

CH3

CH3C8H17

BrBr

(a)

HO

CH3

CH3C8H17

(b)

CH3

CH3C8H17

H3C C O

O

(c)

Example

HO

CH3

CH3C8H17

BrBr

(a)

HO

CH3

CH3C8H17

(b)

CH3

CH3C8H17

H3C C O

O

(c) 20

24.5

Strategy To predict the type of reactions a molecule mayundergo, we must first identify the functional groups present (see Table 24.4).

Solution There are two functional groups in cholesterol: thehydroxyl group and the carbon-carbon double bond.

(b) This is a hydrogenation reaction. Again, the carbon-carbondouble bond is converted to a carbon-carbon single bond.

HO

CH3

CH3C8H17

Example

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24.5

(c) The acid reacts with the hydroxyl group to form an ester andwater. Figure 24.10 shows the products of these reactions.

HO

CH3

CH3C8H17

BrBr

(a)

HO

CH3

CH3C8H17

(b)

CH3

CH3C8H17

H3C C O

O

(c)HO

CH3

CH3C8H17

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Chemistry In Action: The Petroleum Industry

Crude Oil

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