Bài giảng hoá học hữu cơ amine

cyclohexylamine 1o Complex amines are named by prefixing "amino"-" or N-methylamino, N,N-dimethyl amino-, etc.. NH2 NH2 NH2 NH2CH3 CH3 CH3aniline o-toluidine m-toluidine p-toluidine N

Amines

II Synthesis III Reaction

Neurotransmitter

Mushroo m

Amines

Neurotransmitter Hallucinogenic

Ecstasy drug

Dopamine

2o

(CH3)3N trimethylamine

cyclohexylamine

1o

Complex amines are named by prefixing

"amino"-" ( or N-methylamino, N,N-dimethyl

amino-, etc.) to the parent chain:

CH3CH2CHCH2CH2CH3

NH23-aminohexane

NH2 NH2 NH2 NH2

CH3

CH3

CH3aniline o-toluidine m-toluidine

p-toluidine

N CH3

H3C

H N

Nomenclature

Aromatic amines

amine  ammonium + anion aniline  anilinium + anion

CH3CH2CH2NH3+Cl

-n-propylammonium chloride

(C6H5NH3)2SO4anilinium sulfate

Salts of amines

C O

C

cocaine.HCl HCl salt of 3o amine

m 195o C water soluble non-volatile

"powder", "blow"

"snow"

snorted longer "high"

O OCH3O

H

Cl

CH3N

C O

NaHCO3

II Synthesis of amines

1 Reduction of nitro compounds Ar-NO 2 + H 2 ,Ni  Ar-NH 2

2 Ammonolysis of 1 o or methyl halides

Reduction of nitro compounds

Ammonolysis of 1 o or methyl halides

Ammonolysis of alkyl halides is an SN2 reaction The

alkyl halide must be primary or methyl If the alkyl halide

is secondary or tertiary, then an E2 reaction will take place and the product will be an alkene!

Br

+ NH3

NH2

2o RX

H3C C

O

CH3acetone

Hofmann degradation of amides

Synthesis of amines

1 Reduction of nitro compounds 1 o Ar

Ar-NO 2 + H 2 ,Ni  Ar-NH 2

2 Ammonolysis of 1 o or methyl halides R-X = 1 o ,CH 3

Syntheses for each of the following

amines, starting with toluene?

III Reactions of amine

1 Basicity: react with acids

NH2 + HCl NH3+ Cl

-(CH3CH2)2NH + CH3COOH (CH3CH2)2NH2+, -OOCCH3

anilinium chloride

diethylammonium acetate

Basicity

Aliphatic amines Ammonia Aromatic amines

NH3 + H2O  NH4+ + OH

-R-NH2 + H2O  R-NH3+ + OH

-The alkyl group, -R, is an electron donating group -The

donation of electrons helps to stabilize the ammonium ion

by decreasing the positive charge, lowering the ΔH, shifting the ionization farther to the right and increasing the basicity

Aromatic amines are less basic

than aliphatic amines?

Effect of substituent groups on basicity

Electron donating groups make the compounds a stronger base

Electron withdrawing groups make the compounds a weaker base

Common substituent groups:

-NH2, -NHR, -NR2-OH

-OR-NHCOCH3 electron donating

-R

-H

-X-CHO, -COR-SO3H electron withdrawing-COOH, -COOR groups

-CN-NR3+

-NO

Decreasing order of basicity

NH3

4 1 5 3 2

3 Reductive amination

or NaBH3CN CH NHR+ RNH2

or NaBH3CN CH NR2

2o amine

CCH2CH3O

4.Conversion into amides

N N

N OH

5.Electrophilic Aromatic Substitution

-NH 2 , -NHR, -NR 2 are powerful activating groups and

NH3 HSO4

H C C

O

O

h) coupling with diazonium salts  azo dyes

an azo dye

6.Hofmann elimination

step 1, methylation  4o salt

step 2, reaction with Ag2O  4o hydroxide + AgX

step 3, heat to eliminate  alkene(s) + R3N

7 Reactions with nitrous acid

R-NH2 + HONO N2 + mixture of alchols & alkenes

R N

O

p-nitrosocompound