Chemistry 2100 Lecture 3. Discovering Aromatics C6H6C6H6 1.54 Å 1.33 Å 1.39 Å.

Chemistry 2100

Lecture 3

Discovering Aromatics

C6H6 Ladenburg 1878

Dewar 1867CH3C C C C CH3

CHH2C C C CH CH2 Br 2 / Fe

(- HBr )C6H6 C6H5Br

Br 2 / Fe

(- HBr )C6H4Br2

1.54 Å 1.33 Å 1.39 Å

CH3 CH3 CH2 CH2 C6H6

Aromatics H H

H

H

H

H H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H H

H H

H H

Resonance

H H

H H

H H

Resonance

H H

H H

H H

Resonance

H H

H H

H H

Resonance

H H

H H

H H

Resonance

H H

H H

H H

Resonance

H H

H H

H H

Resonance

H H

H H

H H

Resonance

Resonance

Graphene

Carbon Nanotubes

Nomenclature for Arenes

• Many common names retained• Blah• PAH

PhenanthreneAnthraceneNaphthalene Benzo[a]pyrene

Aromatic Reactions

Noteworthy Phenols hexachlorophene

OHCl

Cl Cl

CH2

Cl

ClCl

HO eugenol

HO

CH3O hexylresorcinol

OH

HO OH

Cl

O

CH3HO

OHOH

HN(CH3)2

OH

O

CONH2

aureomycin

O

HO

tetrahydrocannabinol

Phenol Acidity

>>

acids > thiols ~ phenols > water ~ alcohols

C OHCH3

O

OH CH3 OH

Acidity:

acids > phenols ~ thiols > water ~ alcohols

Ka % ionized [H3O+], M pH

~1 107 ~100 ~0.1 1.00

1.8 10–5 1.3 1.3 10–3 2.88

3.3 10–10 0.0036 3.6 10–6 5.44

2.5 10–11 0.0016 1.6 10–6 5.80

1.3 10–16 0.0001 1.0 10–7 7.00

HCl

HOAc

PhOH

EtSH

EtOH

HOH

Comparative acidities of 0.1 M aqueous solutions of representative acids HA

1.8 10–16 0.0001 1.0 10–7 7.00

Phenols as AntioxidantsAutoxidation

CH2CH=CH-CHH

CH2CH=CH-CHSection of a fatty

acid hydrocarbon chainA carbon radical

lightor heat

CH2CH=CH-CH-CH2

O-O-H

A hydroperoxide

CH2CH=CH-CHO-O

CH2CH=CH-CH

H+

+ CH2CH=CH-CH A new carbon radical

Section of a new fattyacid hydrocarbon chain

CH2CH=CH-CH O-O CH2CH=CH-CHO-O

A hydroperoxy radical

+Oxygen is adiradical

Natural Phenolic Antioxidants

HO

O

CH3

CH3CH3CH3

CH3

CH3CH3 CH3

Vitamin E ( tocopherol)Vitamin E tocopherol) OH

OH

HO

Resveratrol

Man-made Phenolic Antioxidants

OH

CH3

BHT

OH

OCH3

BHA

methyl paraben

OC

OCH3

OH

Phenols as… Weapons?

CH2 CH NH2

COOH

phenylalanine

CH2 CH NH2

COOH

phenylalanine

[O]

tyrosine

CH2 CH NH2

COOH

HO

CH2 CH NH2

COOH

phenylalanine

[O]

L-DOPA

CH2 CH NH2

COOH

HO

HO

[O]

tyrosine

CH2 CH NH2

COOH

HO

CH2 CH NH2

COOH

phenylalanine

[O]

L-DOPA

CH2 CH NH2

COOH

HO

HO

[O]

tyrosine

CH2 CH NH2

COOH

HO

CH2 CH NH2

COOH

phenylalanine

[O]

L-DOPA

CH2 CH NH2

COOH

HO

HO

[O]

tyrosine

CH2 CH NH2

COOH

HO

CH2 CH NH2

COOH

phenylalanine -CO 2

CH2 CH2 NH2

HO

HO

dopamine

[O]

L-DOPA

CH2 CH NH2

COOH

HO

HO norepinephrine

CH CH2 NH2

HO

HO

OH

[O]

[O]

tyrosine

CH2 CH NH2

COOH

HO

CH2 CH NH2

COOH

phenylalanine -CO 2

CH2 CH2 NH2

HO

HO

dopamine

epinephrine

"CH 3"CH CH2 NH

HO

HO

OH

CH3

[O]

L-DOPA

CH2 CH NH2

COOH

HO

HO norepinephrine

CH CH2 NH2

HO

HO

OH

[O]

[O]

tyrosine

CH2 CH NH2

COOH

HO

CH2 CH NH2

COOH

phenylalanine -CO 2

CH2 CH2 NH2

HO

HO

dopamine

epinephrine

"CH 3"CH CH2 NH

HO

HO

OH

CH3

[O]

L-DOPA

CH2 CH NH2

COOH

HO

HO norepinephrine

CH CH2 NH2

HO

HO

OH

[O]

[O]

tyrosine

CH2 CH NH2

COOH

HO

CH2 CH NH2

COOH

phenylalanine -CO 2

CH2 CH2 NH2

HO

HO

dopamine

CH CH NH

"phenethylamine"

CH CH NH

ephedrine (ephedra) / pseudoephedrine

OH

CH3 CH3

ephedrine (ephedra) / pseudoephedrine

OH

CH3

CH CH NH

CH3

CH CH NH 2

CH3

methylenedioxymethamphetamine / MDMA / Ecstacy

CH3

CH CH NH 2

O

O

CH3

methylenedioxymethamphetamine / MDMA / Ecstacy

CH3

CH CH NH 2

O

O

CH3

methylenedioxymethamphetamine / MDMA / Ecstacy

CH3

CH CH NH 2

O

O

CH3

methylenedioxymethamphetamine / MDMA / Ecstacy

CH3

Organic Food Dye: Carminic Acid

carminic acid

O

O

OH

COOH

OH

OH

HO

HO

OH

Aromatic Heterocycles

nicotineniacin (B3) / nicotinamide

thiamine (B1)

N

NCH3

N

C NH2

O CH3

NH2

CH3

N

N

CH2

N

S

CH2CH2OHCl

caffeine(theobromine)

CH3

N

N

CH3

N

N(H) CH3

O

O• •

••

Heterocycles store life’s information

(U) T = A

N

N

O

O

H

(H) CH3

Sugar

(U) T = A

Sugar

H

H N N

NN

N

N

N

O

O

H

(H) CH3

Sugar

(U) T = A

Sugar

H

H N N

NN

N

N

N

O

O

H

(H) CH3

Sugar

(U) T = A

Sugar

H

H N N

NN

N

N

N

O

O

H

(H) CH3

Sugar

(U) T = A

Sugar

H

H N N

NN

N

N

N

O

O

H

(H) CH3

Sugar

(U) T = A

Sugar

H

H N N

NN

N

N

N

O

O

H

(H) CH3

Sugar

(U) T = A

Sugar

H

H N N

NN

N

N

N

O

O

H

(H) CH3

Sugar

1.085 nm

(U) T = A

Sugar

H

H N N

NN

N

N

N

O

O

H

(H) CH3

Sugar

1.085 nm

(U) C = G

H

Sugar

H

H

O

N

N

N

N

N

N

N

N

OSugar

H

H