Penamaan 2

Timberlake LecturePLUS

1999 1

Aromatic Hydrocarbons


1999 2

Aromatic Compounds and

Benzene

Aromatic compounds contain benzene.

Benzene, C6H6 , is represented as a six carbon

ring with 3 double bonds.

Two possible can be drawn to show benzene in

this form.

H

H

H

H

H

H

H

H

H

H

H

H


1999 3

Benzene Structure

The structures for benzene can also be written

as a single structure where the alternating

double bonds are written as a circle within the

ring.

Benzene

structure


1999 4

Aromatic Compounds in Nature and

Health

Many aromatic compounds are common in nature

and in medicine.

COOH

COOCH3

CHO

OCH3

OH

Aspirin Vanillin

CHCOOH

CH3

CH3CHCH2

CH3

Ibuprofen


1999 5

Naming Aromatic Compounds

Aromatic compounds are named with benzene as the parent chain.

One side group is named in front of the name benzene.

methylbenzene chlorobenzene

(toluene)

CH3 Cl

6

Monosubstituted Benzenes

are named using benzene as the parent name preceded

by the substituent name (as a prefix; all one word):

F NO2 CH2CH3

fluorobenzene nitrobenzene ethylbenzene

7

Alkyl-substituted Benzenes

Alkyl substituted benzenes are named according to

the length of the carbon chain of the alkyl group.

With six carbons or fewer in the alkyl chain, they

are named as alkylbenzene.

e.g., propylbenzene:

CH2CH2CH3

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Alkyl-substituted Benzenes

With more than six carbons in the alkyl chain, they are

named as a phenylalkane, where the benzene ring is named as a substituent (phenyl) on the alkane chain

e.g., 4-phenylnonane

CHCH2CH2CH2CH2CH3

CH3CH2CH2

CHCH2CH2CH2CH2CH3

CH2CH2CH3

CH3CH2CH2CHCH2CH2CH2CH2CH3=

4-phenylnonane

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Common Names of Subs.

Benzenes

There are a number of nonsystematic (common)

names commonly used for certain

monosubstituted benzenes

These common names should be memorized.

These common names are used as base names

when naming di- or trisubstituted aromatic

compounds derived from them.

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Common Names of Subs. Benzenes Do you still remember ?

Toluene

(an alkybenzene)

Anisole

(an eter)

benzaldehyde

benzoic acid

benzonitrile

Cumene

(an alkylbenzene)

Acetophenone

(a keton)

Styrene

(an alkylene Benzene)

Phenol

(an alcohol)

Aniline

(amine)

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Common Names of Subs. Benzenes

C H 3 O H

O C H 3

N H 2

C C H 2

H

C

O

H C

O

O H

C N

C

O

C H 3

C H C H 3

C H 3

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Common Names of Subs. Benzenes

CH3 OH

OCH3

NH2

CCH2

H

C

O

HC

O

OH

C N

C

O

CH3

CHCH3

CH3

toluene phenol aniline

anisolestyrene

benzaldehyde benzoic acid acetophenone

benzonitrile cumene

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Disubstituted Benzenes

ortho- = o- = 1,2-disubstituted

(two groups on adjacent carbons on the

ring)

F

F

o-difluorobenzene or1, 2-difluorobenzene

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meta- = m- = 1,3-disubstituted

(two groups having one unsubstituted

carbon between them)

BrBr

m-dibromobenzene or1, 3-dibromobenzene

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para- = p- = 1,4-disubstituted

(two groups on opposite sides of the ring)

Cl

Cl

p-dichlorobenzene or1, 4-dichlorobenzene

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Disubstituted Benzenes When one of the substituents changes the base name,

o-, m-, and p- can be used to indicate the position of the other substituent.

Br

NH2

OH

Cl

p-bromoaniline

or

4-bromoaniline

o-chlorophenol

or

2-chlorophenol

1 2

3 4 1

2

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The Phenyl Group

When a benzene ring is a substituent, the term phenyl is

used (for C6H5 )

You may also see Ph or f in place of C6H5

Benzyl refers to C6H5CH2

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Relative positions on a benzene ring

ortho- (o) on adjacent carbons (1,2)

meta- (m) separated by one carbon (1,3)

para- (p) separated by two carbons (1,4)

Describes reaction patterns (occurs at the para position)

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Common Names of Disubs. Benzenes

There are a few nonsystematic (common) names for

disubstituted benzenes that you should be familiar with:

CH3

CH3

CH3

CH3

CH3

CH3o-xylene m-xylene p-xylene

CH3

OH

CH3

OH

CH3

OHo-cresol m-cresol p-cresol

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Polysubstituted Benzenes

The ring is numbered in a direction to

encounter the next substituent with the

lowest number.

The substitutents are listed in alphabetical

order when writing the name.

Common names of the monosubstituted

benzenes are used as parent names for

polysubstituted aromatics.

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Polysubstituted benzenes are named by numbering the

position of each substituent on the ring (with more than

two substituents, numbering must be used rather than o-

, m-, and p-.)

The numbering is carried out to give the substituents the

lowest possible numbers.

Carbon #1 is always a carbon bearing a substituent.

For rings with common names, the carbon bearing the

substituent responsible for the common name is always

carbon #1.

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Benzenes With More Than Two

Substituents

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Br

CH2CH3

NO2

OH

Cl

Br1 2

3 4

5

1

2

3 4

4-bromo-2-ethyl-1-nitrobenzene 5-bromo-2-chlorophenol

25


CH3

Cl

Br

O2N

CH2CH3

Cl

Br

O2N

1 3

4 5

6

6

5 4

3

2 2

1

2-bromo-6-chloro-4-nitrotoluene 1-bromo-3-chloro-2-ethyl-5-nitrobenzene

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Polycyclic Aromatic Hydrocarbons (PAH)

anthracene

phenanthrene

naphthalene

pyrene benzo [a] pyrene

27

Aromatic Hydrocarbons

From high temperature distillation of coal tar

28

Problem

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