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Chapter 15 Amine and Nitriles

I Classification and nomenclature of amines

II physical properties

III Basicity of amines

IV Preparation of amines

V Reactions with inorganic acids

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I. Classification and nomenclature of aminesAmine: derived fromNH3

Primary amines: RNH2

Secondary amines: RNHR 〞Tertiary amines: 　　　 RNR′R 〞 Quaternary ammonium compounds:

XNR4

（氨）伯胺仲胺叔胺

季铵盐

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Examples:CH3NH2 CH3CH2NH2

methylamine ethylamine tert-butylamine

C NH2CH3

CH3CH3

CH3NHCH2CH3NH2 (CH3CH2)2NH

diethylamineaniline methyethylamine

(CH3CH2)3NH

Triethylaminemethylethylpopylamine

CH3 N CH2CH2CH3

CH2CH3

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p-minobengoic acid

(CH3)4N+Cl-

Tetramethyl ammonium chloride

NH2CH3

CH3CHCH2CHCH2CH3

2-methyl-4-aminohexane

H2N COOH

回目录

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II physical properties

Polarity: moderately polar Hydrogen bond: Primary and secondary amines can form strong

hydrogen bonds to each other and to water. Tertiary amines cannot form hydrogen bonds to

each other but they can form hydrogen bonds to water.

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III Basicity of amines

similar to NH3 ， sp3 hybtidized.

1.Structure feature of amines.

N

H

HH

NH3

CH3CH3

NH3C

N

H

HH3C

CH3NH2 (CH3)3N

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(1) Lone pair of electrons.

a. Arimary amines

Secondary amines

Tertiary amines

CH3CH2NH2

(CH3CH2)2NH

(CH3CH2)3N and ammonia

2. Basicity

(2) Compairison of basicity.

NH3

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b. Aliphatic amines

Aromatic amines

CH2NH2

NH2

NO2

NH2

CH3

NH2

Consider from:

a. Inductive effectb. Conjugative effectc. Steric effect

Conclusion? Consider (F3C)3N?

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IV Preparation of amines

1.Alkylation of ammonia.

BrHNHCBrHC 35252

BrHNNHHCNHBrHNHC 42523352

BrHNHCBrHCNHHC 225252252 )(

BrHNNHHCNHBrHNHC 425232252 )( )(

HBrNHCBrHCNHHC 35252252 )( )(

BrHNNHCNHHBrNHC 43523352 )( )(

BrNHCBrHCNHC 45252352 )( )(

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3.Reduction of nitriles and amides.

Specially suitable for preparing secondary and tertiary amine.

NC-CH2CH2CH2CH2-CN H2N-CH2 (CH2)4CH2NH2

H2/Ni

hexadiamineRCH2NH2RCONH2

LiAlH4 H2O

LiAlH4 H2O

LiAlH4 H2O

RCONHR'

RCON R'R''

RCH2N R'R''

RCH2NHR'

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4. Reduction of nitro compounds

Discuss different reductants used in reduction.

HNO3

H2SO4

NO2Fe / HCl

or H2 / Ni

NH2

Specially suitable for preparing aromatic amines.

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5.Hofmann degradation(降级 )

RNH2 　　

Producing amines with one less carbon.

RCONH2

NaOX / 2NaOH　　+Na2CO3 　　

+NaX+H2O

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V. Reactions with inorganic acids

CH3CH2NH2 CH3CH2 N+H3Cl-

(CH3CH2) 2 NH (CH3CH2) 2 N+H2Cl-

(CH3CH2) 2 N (CH3CH2) 3N+H2Cl-

1. Reactions with inorganic acids

HCldil

HCldil

HCldil

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Applications:

1.Distinguishing amines from nonbasic compounds that are water insoluble.

2.Separating amines from nonbasic compounds that are water insoluble.

Examples:

1.Distinguish from

NH2

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2. Separate CH3 (CH2)10 CH3(b.p.221 。 C)

with CH3 (CH2)9NH2 (b.p.216 。 C)

CH3 (CH2)10 CH3

CH3 (CH2)9NH2

dilHCl

Organic Layer

Water LayerCH3 (CH2)10 CH3

Water Layer(NaCl)

Organic Layer

Water Layer

CH3 (CH2)9NH2NaOH

CH3 (CH2)9NH2·HCl

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2.Acylation (with acid chloride or anhydride)

CH3COCl RNH2 CH3CONHR HCl++

CH3COCl RNHR'+ CH3CONHR HClR'

+

CH3COCl R N R''R'

+ no reactionNH2

(CH3CO)2O+NHCOCH3

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Applications:

(2) Protect-NH2 from oxidation

(1) Prepare one amine form another amine.

NHCH 23 )( 233 )(CHCONCH

2323 )(CHNCHCH

COClCH 3 41 LiAlH)OH22)

NO2

NH2NH2

Example:

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NH2 NHCOCH3HNO3

NHCOCH3H2O / H+

NO2

NH2

CH3COCl

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4.Sulfonylation

RNH2 + SO2Cl RNHSO2NaOH

H2ORN- SO2

Na+

RNHR'+ R N SO2

R'

SO2ClCH3NaOH

R'R N R''

(Similar to alylation)

soluble

unchanged (oil-like makerial)

Separating and distinguishing three types of amine.

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XRNXNR 22 ][RNH2NaNO2 / HCl

0~5℃

5.Nitrosation

(1)With primary amines

a. Primary aliphatic amines

Alkene,alkyl halide

or alcohol etc.

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NH2NaNO2 / HCl

N2Cl-+

b.Primary aromatic amines.

(stable if keept below 5 )℃Diazonium salt