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Organic Chemistry II

University of Lincoln presentation

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• Contain double or triple bonds, but do not show the same reactivity as other unsaturated hydrocarbons

• Benzene: C6H6

• Used mainly as solvents• Substitution rather than Addition is favoured

H

H

H

H

H

H

Aromatic Hydrocarbons

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Delocalisation, Resonance:Stabilise molecules, so make them less reactive

Three sp2 hybrid orbitals arrange themselves as far apart as possible-which is at 120° on a plane. The remaining p orbital is at right anglesto them.

Each carbon atom uses the sp2 hybrids to form σ-bonds with two other carbons and one hydrogen atom.

Delocalised or Conjugated System: π-bonding electrons can move within the molecule

Resonance Structure:Rearrange the bonding

electrons

HHH

HH

HH

HHH

6 p-orbitalsDelocalised orbital clouds

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Flurobenzene

Toluene

Ethylbenzene

2,4,6-Trinitrotoluene (TNT)

Aniline

1,2-Dichlorobenzene

Phenol

1,3-Dichlorobenzene

1,4-Dichlorobenzene

o-Xylene

m-Bromostyrene

Benzoic acid

-ortho

-para

-meta

FCH3 CH3 NH2

Cl

Cl

O

OHOH Cl

Cl

Cl

Cl

CH3

CH3

CH2

Br

N+

O-

O

N+

O-

O

N+

O-

O

CH3

Naming Aromatic Hydrocarbons

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Substitution

• Aromatic Substitution reaction – Aromatic compound loses a hydrogen atom and another atom or group takes its place.

• It is possible for substitution to occur in more than one place on the ring.

+ HNO3

H2SO4H2O

N+ O

-O

+

N+ O

-O

N+

O-

O

otha-Dinitrobenzene

para-Dinitrobenzene

meta-Dinitrobenzene

N+ O

-O

N+

O-

O

N+ O

-O

N+

O-

O

Cl2 AlCl3Cl BrFeBr3Br2

Reactions of Aromatic Hydrocarbons

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• –OH group (hydroxyl group)• Replace -e with -ol

• CH3OH, methanol, simplest

alcohols are classified as primary (1°), secondary (2°), or tertiary (3°) depending on the number of carbon atoms bonded to the carbon bearing the -OH group

OHCH3 H

H

CH3

OH

CH3

H

CH3

CH3CH3

OH

Primary Alcohol (1o)

Secondary Alcohol (2o)

Tertiary Alcohol (3o)

Alcohols

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Polyhydroxy alcohols are alcohols that possess more than one hydroxyl group

methanol

ethanol propanol

2-propanol or propan-2-ol or isopropyl alcohol

2-ethyl-1-butanol or 2-ethyl-butan-1-ol

CH3 OH CH3

OH

CH3

OH

CH3 CH3

OH

CH3 CH3

OH

1,2-Ethanediol (ethylene glycol)

1,2-propanediol (propylene glycol)

1,2,3-propanetriol (glycerol)

OHOH

CH3

OH

OH

OH

OH

OH

Naming Alcohols

CH3 OH

CH3 CH3

CH3

O

H CH3

O

OH

Oxidation Oxidation

Reduction

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■ Reaction with acids to produce Esters

■ Redox reaction (Reduction and oxidation)

Ethanol

Acetic Acid(ethanoic acid)

Ethyl acetate

CH3

O

OH

+CH3

OH

HCl or H2SO4 (H+ Catalyst) CH3

O O CH3

OH2+

Acetaldehyde

Alcohol Dehydrogenase

Acetic Acid

Reactions of Alcohols

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• –O- group (ether group)

• CH3OCH3, dimethyl ether simplest

• Soluble in water- H-bonding to water - Polar• Flammable – Ether can cause flash fires• Low Reactivity – Make Good Reaction Solvents• Naming: alkyl groups in alphabetical order followed by

ether

Ethers

Naming Aldehydes Change -e ending to –al

ethane ethanal (acetaldehyde)

Ketones Change -e ending to –onepropane propanone

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• Both contain a carbonyl group (C=O)

Aldehyde Ketone

R

H

O

R

R

O

CH3

H

O

CH3 CH3

O

Aldehydes and Ketones

Reactions of Aldehydes and ketones

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Synthesis: produced by oxidation of alcohol

Reduction of carbonyl group to produce alcohols

OH

CH3 H

H

O

CH3

H

PrimaryAlcohol

Oxid

atio

n

Reduct

ion

CH3

OH

CH3

H

CH3

O

CH3

SecondaryAlcohol

Oxid

atio

n

Reduct

ion

TertiaryAlcohol

Cannot be oxidised

CH3

CH3CH3

OH

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CH3

H

O

CH3

CH3

O

CH3

OH

O

OH

H

O

OH

CH3

O+

Oxid

atio

n

Stro

ng

Oxid

atio

n

Reduct

ion

Reduct

ion

Carboxylic acid

Oxidation of carbonyl group

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• Contains C=O and –OH group on same carbon

• Change -e to -oic acid• Acetic acid: acid in vinegar• Simplest: methanoic acid (formic acid)

Methanoic acid Ethanoic acid Propanoic acid

O

OH H CH3

O

OH

O

OHCH3

Carboxilic acids

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■ Esterification reactions

■ Reduction to aldehydes

Acetic Acid(ethanoic acid)

Ethyl acetate

CH3

O

OH

+CH3

OH

HCl or H2SO4 (H+ Catalyst) CH3

O O CH3

OH2+

Reactions of Carboxilic acids

CH3H

O

CH3OH

OO xid a tion

R ed u ction

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• Derived from carboxylic acids and alcohols• Tend to be fragrant

– Methyl butyrate apple– Ethyl butyrate pineapple

• An ester name has two parts - the part that comes from the acid (propanoate) and the part that shows the alkyl group (methyl).

Example: Methyl propanoate CH3

O

OCH3

Ester

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Substitution Reduction of esters

Hydrolisis of esters (basic)

Ester

Acid

Amide

O

ORR

1

O

ORR2

O

ORH

O

NHRR2

R2OH

R+

H2O

R2NH

base

LiAlH4 +R1

R2

O

R1

OH

H

H OHR2+

Carboxylate ester

Sodiumhydroxide

SodiumCarboxylate

Alcohol

R

O R1

O

+ NaOHsaponification

or hydrolysisR

O-

O

Na+

+ R1OH

Reactions of Esters

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• Derived from ammonia by substituting H for alkyl groups. It is an alkali

• We have primary, secondary or tertiary amines depending on the number of H substituted

N

HH

H

N

HH

R

N

HR1

R

N

R2R1

R

Amines

AmmoniaPrimary amine (1o)

Secondary amine (2o)

Tertiary amine (3o)

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1,4-butanediaminePutrescine (found in decaying meat) (1o) Amphetamine

(dangerous stimulant) (1o)

PiperidineTriethylamine (3o)

Isopropylamine (1o)

1,5-pentanediamineCadaverine (found in the putrefaction of cadavers

NH2

NH2CH3

NH2

N

H

N

CH3 CH3

CH3 CH3 CH3

NH2

NH2 NH2

Amines

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Alkylation

Oxidation reduction

R X R1 NH22+ N

R1

R

H + N+

H

H

HR1 Na+

Phenylamine

N+ O

-O

NH2

Reduction

Oxidation

Reactions of Amines

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Acknowledgements

• JISC• HEA• Centre for Educational Research and Developmen

t• School of natural and applied sciences• School of Journalism• SirenFM• http://tango.freedesktop.org