Polycyclic Aromatic Compounds

Polycyclic  Aromatic  Compounds Polycyclic  Aromatic  Compounds - Start

2018-03-15 22K 22 0 0

Polycyclic Aromatic Compounds - Description

1. Nomenclature . of Polycyclic Aromatic Compounds. Polycyclic . aromatic compounds have two or more benzene rings fused together. 2. Naphthalene, anthracene and phenanthrene are obtained from . coal tar. ID: 651502 Download Presentation

Download Presentation

Polycyclic Aromatic Compounds




Download Presentation - The PPT/PDF document "Polycyclic Aromatic Compounds" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.



Presentations text content in Polycyclic Aromatic Compounds

Slide1

Polycyclic Aromatic Compounds

1

Slide2

Nomenclature of Polycyclic Aromatic Compounds

Polycyclic

aromatic compounds have two or more benzene rings fused together

2

Naphthalene, anthracene and phenanthrene are obtained from

coal tar

, naphthalene being the

most abundant

(5%) of all constituents of coal tar.

Uses: moth balls, which contain naphthalene, are used as insect repellants (naphthalene is

very

volatile

).

Many

synthetic dyes

contain naphthalene moiety.

Slide3

MonosubstitutedNaphthalene is often designated by Greak Letter

3

Slide4

More Naming

4

Slide5

Bonding in Polycyclic Aromatic Compounds

In

benzene, all C-C bond lengths are equal ( equal distribution of

pi

electrons

around the benzene ring).In the polycyclic aromatic compounds, the C-C bond lengths are notthe same ( e,g. the distance between carbon 1 and 2 =1.36 A°in naphthalene is smaller than the distance between Carbon 2 and 3 = 1.40 A°) there is no equal distribution of pielectrons

around naphthalene

5

Slide6

Resonance Energy of Polycyclic Aromatic Compounds

6

Slide7

Bonding

in Polycyclic Aromatic Compounds

The resonance energy per ring is less than that of

benzene suggest

the

polycyclic aromatic compounds are more reactive than

benzene.

reaction

at one ring loses less energy because the product still have one or more intact

benzenoid

rings

.

7

Slide8

Example

The

product still has two benzene rings ; it loses only 20 Kcal/

mol

8

Slide9

Oxidation of Naphthalene

Naphthalene can be oxidized to products in

which much of the

aromaticityi

s retained.

9

Vitamin K

Slide10

10

Reduction of Polycyclic Aromatic Compounds

The polycyclic aromatic compounds (unlike benzene) can be hydrogenated without heat or pressure , or they can be reduced with sodium and

ethanol

Slide11

11

Hydrogenation of Polycyclic Aromatic Compounds

Hydrogenation

of Polycyclic Aromatic Compounds requires heat and pressure just as it does for benzene

Slide12

12

Electrophilic Aromatic

Substitution of Naphthalene

Naphthalene

undergoes

electrophilic aromatic substitution predominately at the 1-position (α-position)

Slide13

13

More Electrophilic Aromatic

Substitution

Reactions

Slide14

14

Position of Substitution of Naphthalene

1-substitution Mechanism

Resonance

structures for the 1-substitution

intermediate

7 resonance structures; 4 aromatics (major)

Slide15

15

Sulfonation of

Naphthalene

Slide16

16

1-naphtalenesulphonic acid

2-naphtalenesulphonic acid

Less stable

More

stable

Slide17

17

Kinetic vsThermodynamic

Control

Slide18

18

2-position mechanism

Resonance structures for the2-substitution intermediate

Only 6 resonance structures;

2

aromatics

Slide19

19

19

Substituted naphthalene

Activating groups direct the electrophile to the same ring, while deactivating groups direct it to the other ring.

Elctrodonating

group (EDG):

NH

2

, OH, OR, alkyl

Electrowithdrawing

group

(EWG):

NO

2

, CO, COOH, CN, SO

3

H

Slide20

20

Substituted naphthalene

Slide21

21

Slide22

22

Howarth

method

Naphthalene Synthesis

Slide23

23

Other way of cyclization

Slide24

24

Synthesis of 1-alkyl naphthalene

Slide25

25

Naphthalene derivatives

Naphthols

Preparation:

Slide26

26

Reaction of

 and -

naphthols

with aryl

diazonium salt

Naphthols

Slide27

27

Reaction

of

 and -

naphthols

with nitrous acid

Slide28

28

Conversion of

 and -

naphthols

to

naphthyl ether

Slide29

29

Naphthaquinones

There are six possible

naphthaquinones

, but only common are 1,2; 1,4; 2,6-

naphthaquinones

Slide30

30

Preparation of naphthaquinones

1,4-

Naphthaquinone

Slide31

31

31

Preparation of naphthaquinones

1,2-

Naphthaquinone

Slide32

32

32

32

Preparation of naphthaquinones

2,6-

Naphthaquinone

Slide33

33

Anthracene

Slide34

34

Synthesis

Slide35

35Chemistry

Reactions

Slide36

36

Slide37

Slide38


About DocSlides
DocSlides allows users to easily upload and share presentations, PDF documents, and images.Share your documents with the world , watch,share and upload any time you want. How can you benefit from using DocSlides? DocSlides consists documents from individuals and organizations on topics ranging from technology and business to travel, health, and education. Find and search for what interests you, and learn from people and more. You can also download DocSlides to read or reference later.