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Aromatic. Compounds. Good Aromatics. cinnamon. O ║. CH ═ CH – C – H . cinnamaldehyde. coffee. O ║. CH3. 3HC. N. N. O ║. N. N. CH3 . caffeine. vanilla. OH. OCH3. H – C ═ O. vanillin. Filipino BBQ goodness: puto (rice muffins). a niseed/anise. OCH3. CH ═ CH – CH3.

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Aromatic

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Aromatic

Aromatic

Compounds


Aromatic

Good

Aromatics


Aromatic

cinnamon

O

CH ═ CH – C – H

cinnamaldehyde


Coffee

coffee

O

CH3

3HC

N

N

O

N

N

CH3

caffeine


Vanilla

vanilla

OH

OCH3

H – C ═ O

vanillin


Aromatic

Filipino BBQ goodness: puto (rice muffins)

aniseed/anise

OCH3

CH ═ CH – CH3

ANETHOlE


Cloves

cloves

OH

OCH3

CH2 – CH ═ CH2

eugenol


Wintergreen

wintergreen

O

C – O – CH3

OH

Methyl salicylate


Chamomile

chamomile

O

O

COUMARIN


Aromatic

Bad

Aromatics


Benzene

benzene

benzene


Naphthalene

naphthalene

nApHthalENE


Burnt meat

burnt meat

PHEnANTHRENE


Smoke belchers

smoke belchers

BEnZOPYRENE


Smoke belchers1

smoke belchers

PYRENE

CORONENE


Cigarettes

cigarettes

BEnZanthRacENE

diBEnZanthRacENE


Cigarettes1

cigarettes

NO

N

N

nITROSONORNICOTINE


Lets try to find out the missing piece of the puzzle that leads to that occurrence

Lets try to find out the missing piece of the puzzle that leads to that occurrence…


Aromatic

HISTORY


Let us learn to dream gentlemen and then perhaps we shall learn the truth 1890 kekul

“ Let us learn to dream, gentlemen, and then perhaps we shall learn the truth.” -1890 Kekulé -


Aromatic

Some of the early researchers in organic chemistry became intriguedby fragrant oils that could be extracted from certain plants. The compounds responsible for thearomas, had similar chemical properties. As a result, they weregroupedtogether and calledAROMATICS COMPOUNDS.


Aromatic

As more and more aromatic compounds wereisolated and studied, chemist gradually realized that aromatic contained six carbon atoms and had low hydrogen – to – carbon ratios (relative to other hydrocarbon). They also realized that the term aromatic was not always accurate. Because there are many fragrant compounds do not have aromatic properties.


Aromatic

1825 – Michael Faradaydiscovered BENZENE in whaleoil.When BENZENE was found to have the formula C6H6, scientist was puzzled.They tried unsuccessfully to draw a straight – line structure for BENZENE.


Benzene s possible structures

BENZENE’s possible structures

CH3— C ≡ C ─ C ≡ C — CH3

2,4 – hexadiyne

CH2═ CH ─ C ≡ C ─ CH ═ CH2

1,5 – hexadien – 3 – yne


Aromatic

Kekule was to say later that he must have dozed off at this point. In his dreamthe black balls of carbon turned into black impswith forked tails that began racing around the room and would soon be upsetting the apparatus of the laboratory. He was ready to run the rascals out. Then, almost suddenly, the confusion died away as each imp grabbed the tail of the one ahead of him, the six forming a whirling circle. One hand of each imp held a tail, the other a white handkerchief--and they waved to him as the group whirled by. He said that he came awake with a start, realizing that the imps were acting out the formula for benzene. As his hand grabbed the sketching pencil, the imps were back to black balls again and the handkerchiefs had changed to hydrogen atoms. How simple the arrangement turned out to be. “The carbon atoms of benzene form a ring."


Aromatic

1858 – Friedrich August von StradonitzKekulé.Suggested that the six carbon atoms formed a cyclic structure having three sets of alternating double bonds.1865 – Kekulé proposed that BENZENE had two structural formulas and that is alternated between them.


Aromatic

1931 – Linus Pauling To help explain molecules like benzene, he proposed resonance theory. (Pauling also gave us hybrid orbitals, electronegativity, and valence bond theory).That gave birth to the modern structure of BENZENE.


Modern benzene structure

Modern benzene structure


Nomenclature

Nomenclature


Rule 1

Rule # 1

  • When a single hydrogen of the benzene ring is replaced, the compound can be named as a derivative of benzene.


Examples

Examples:

Cl

chlorobenzene

CH2CH3

Br

NO2

ethylbenzene

nitrobenzene

bromobenzene


Rule 2

Rule # 2

  • A number of benzene derivatives are known by common names that are also IUPAC – accepted and are used preferentially over other possibilities.


Examples1

Examples:

CH3

NH2

O

OH

C — OH

Aniline

Toluene

Benzoic Acid

Phenol


Aromatic

O

C – H

EXAMPLES

O

C – CH3

benzaldehyde

acetophenone

O

C

benzophenone


Rule 3

Rule # 3

  • Compounds formed by replacing a hydrogen of benzene with more complex hydrocarbon group can be named by designating the benzene ring as substituent.

  • We called them phenyl group.

  • benzyl


Examples2

Examples:

3HC

CH3CHCH ═ CH2

Br

ا

ا

ا

CH3— C — C — C — CH3

ا

ا

ا

Br

3HC

3 – phenyl – 1 – butene

2,2 – dibromo – 4,4 – dimethyl – 3,3 – diphenylpentane


Aromatic

OH

CH2

2 – benzyl – 4 – chlorophenol

Cl


Rule 4

Rule # 4

  • When two groups are attached to a benzene ring, three isomeric structures are possible. They can be designated by the prefixes ortho (o), meta (m), and para (p):


Examples3

Examples:

CH3

CO2H

Cl

Br

NO2

O - bromochlorobenzene

Cl

m – nitrobenzoic acid

p - chlorotoluene


Examples4

Examples:

CH3

CH3

CH3

CH3

CH3

1,2 – dimethylbenzene

1,4 - dimethylbenzene

CH3

p - xylene

O – xylene

1,3 - dimethylbenzene

m – xylene


Rule 5

Rule # 5

  • When two or more groups are attached to a benzene ring, their positions can be indicated by numbering the carbon atoms of the ring so as to obtain the lowest possible numbers for the attachment positions.

  • Group that comes first in alphabeticalorder is given the lower number.


Examples5

Examples:

CH3

Br

Cl

OH

O2N

NO2

Br

NO2

I

3 – bromo – 5 - nitrotoluene

1 – bromo – 2 – chloro – 4 – iodobenzene

NO2

2,4,6 – trinitrophenol


Examples6

Examples:

CH3

NO2

NO2

2ON

TNT

NO2

NO2

NO2

1,3,5 – trinitrobenzene

2,4,6 - trinitrotoluene


Preparation

Preparation

  • Major sources of aromatic compounds are petroleum and coal tar – (a sticky, dark – colored material derived from coal.

  • Natural sources

  • Can be synthesize synthetically


Physical

Physical

Properties


Physical properties

Physical Properties

  • Similar to those of ALKANES & ALKENES

  • Non – Polar

  • Insoluble in water (hydrophobic)

  • Flammable

  • Low density in water


Chemical

Chemical

Properties


Benzene reactions

Benzene Reactions

  • Halogenation

  • Nitration

  • Sulfonation

  • Alkylation


Aromatic

Industrial

Applications


Medicine

Medicine


Medicine1

Medicine


Antiseptic

Antiseptic


Consumer products

Consumer Products


Disinfectant

Disinfectant


Synthetic fiber

Synthetic Fiber


Plastic

Plastic


Preservatives

Preservatives


Aromatic

Dyes


Fuel additives

Fuel Additives


Aromatic

– fin –


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