Amines, Nomenclature, Physical properties and Chemical reaction

Presentation by: Md. Shabab Mehebub

ID: 2015-1-77-004

Amines

•Amines are organic derivatives of ammonia (NH3), in which one or more alkyl, cycloalkyl, or aromatic groups replace hydrogen and bond to the nitrogen atom.

Methylamine Trimethylamine Methylpropylamine

Methylphenylamine Cyclohexyldimethylamine

Classification of Amines

Classified as primary, secondary and tertiary[according to the number of groups attached to the nitrogen atom].

1o amine 2o amine 3o amine

Nomenclature for amines

• Common and IUPAC systems are used extensively for naming amines.

• In the common system, rules similar to what we have seen for ethers are employed, naming the alkyl/aromatic groups attached to the functional group, and then following these with “amine”

Methylamine Trimethylamine Methylpropylamine

Methylphenylamine Cyclohexyldimethylamine

Nomenclature for amines

• The IUPAC system for naming amines is as follows:

– Select the longest carbon chain bound to the nitrogen as the parent chain

– Name the chain by changing the alkane name for this chain: drop the “e” and add “amine”

– Number the chain to give the nitrogen the lowest numbering

– The number and identity of other substituents (including any on the main chain) are indicated at the beginning of the amine name (some are attached to N)

• Some examples-

2-Butanamine

1-Butanamine

# to indicate placement of NH2 group4-C chain (“butane”; - “e” + “amine”)

3-Aminobutanoic acid4-Amino-4-chloro-2-pentanone

• Where NH2-substituted alcohols or other compound cases are involved, the NH2-group is called an “amino” substituent.

Functional group priority

• Aromatic amines involve an amine-type nitrogen bound to an aromatic ring. The simplest case for these is aniline.

Aniline 3-Bromo-2-chloroaniline

• For substituted anilines, the substituent names are treated in a manner similar to what was shown for substituted parent chain cases

Aniline 3,N-DimethylanilineN-Ethyl-N-methylaniline

Physical properties of amines

• Amines tend to be gases for low molecular weight cases (e.g. up to (CH3)3N, trimethylamine) and many heavier ones are liquids at room temperature.

• One very noticeable thing about amines is that they tend to exhibit strong odors. For example, some have a “fishy” smell

Cadaverine(1,5-Pentanediamine)

Putrescine(1,4-Buntanediamine)

Physical properties of amines• Amine boiling points are intermediate of those for alcohols

and alkanes of similar molar mass.

• Because of the presence of N-H bond(s) in primary and secondary amines, hydrogen-bonding is sometimes possible; however, because N is not as electronegative as O, the N-H bond is not as polar as an O-H bond (weaker H-bonding).

Physical properties of amines

• Amines tend to be water-soluble because of H-bonding interactions with water molecules. In fact, amines having fewer than six carbon atoms are infinitely water-soluble.

• Water-solubility decreases as:– Chain length increases, and,

– The degree of N-substitution increases

Chemical reaction of Amines

• Amines are similar to ammonia in their reactions.

• Like ammonia, amines are basic.

• Like ammonia, amines are nucleophilic and react with alkyl

halides, acid chlorides, and carbonyl compounds.

• The aromatic amines are highly reactive in electrophilic

aromatic substitution.

Amine gives this Chemical reactions:

1. As bases

2. Alkylation

3. Conversion into amides

4. Hofmann elimination from quaternary ammonium salts

5. Reactions with nitrous acid

6. Carbylamines Reaction

7. Oxidation of Amines

8. Substitution in Benzene ring of Aniline

NH2 + HCl NH3+Cl-

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

anilinium chloride

diethylammonium acetate

1. Amines reaction as Base

Amine react as base and formed salt.

aniline

Diethylamine

2. AlkylationRNH2

R-XR2NH

R-XR3N

R-XR4N+X-

1o 2o 3o 4o salt

SN2: R-X must be 1o or CH3

CH3CH2CH2CH2BrNH3

CH3CH2CH2CH2NH2

n-butylamine

Amines react as a

nucleophiles with alkyl

halides via substitution

reaction SN2 .

3o Amines make

Quaternary Ammonium

salt.

Example

CH3CH2CH2NH2

CH3ClCH3CH2CH2NHCH3

n-propylamine methyl-n-propylamine

NH2

2 CH3CH2BrN

Et

Et

aniline N,N-diethylaniline

H2C NH2

benzylamine

(xs) CH3I H2C N

CH3

CH3

CH3 I

benzyltrimethylammonium iodide

R-NH2 + RCOCl RCONHR + HCl

1o N-substituted. amide

R2NH + RCOCl RCONR2 + HCl

2o N,N-disubstituted. amide

R3N + RCOCl No reaction

[ cause No Substitution Hydrogen]

3o

3. Conversion into Amide

NH2 + (CH3CO)2OHN C CH3

O

N-phenylacetamide

C

O

Cl

(CH3CH2)2NH + C

O

N CH2CH3

CH2CH3

N.N-diethyl-m-toluamide

N CH3

CH3

+ CH3CO

Cl

NR

H3C H3C

DEET

Example

4. Hofmann elimination from quarternary hydroxides

step 1, exhaustive methylation 4o salt

step 2, reaction with Ag2O 4o hydroxide + AgX

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

Mechanism:

CH3CH2CH2CH2

(xs) CH3I

CH3CH2CH2CH2NH2 N

CH3

CH3

CH3 I-

CH3CH2CH2CH2 N

CH3

CH3

CH3 I-Ag2O

CH3CH2CH2CH2 N

CH3

CH3

CH3 OH- + AgI

CH3CH2CH2CH2 N

CH3

CH3

CH3 OH

CH3CH2CH=CH2 + (CH3)3N

Example -

5. Reactions with nitrous acid

NH2 + HONO N N diazonium salt

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

primary amines

secondary amines

HN R + HONO N R

NO

N-nitrosamine

tertiary amines

N R

R

+ HONO N R

R

N

Op-nitrosocompound

6. Carbylamine reaction

• Primary amine reaction with CHCl3 and KOH under the 60 0-70 0 degree temperature. Then isocyanide[Carbyl-amine] with unpleasent smell found.

• Aliphatic Amine-

• Aromatic Amine-

• Secondary and tertiary amines have no reaction.

7. Oxidation of Amines

Oxidation with KMnO4 : H

• CH3-CH2-NH2 + [O] H2SO4KMnO4 CH3-CH=NH H+ CH3-C=O +NH3

ethylamine ethanal

Primary aliphatic amines oxidation by KMnO4 and produce ethanal.

Oxidation with H2O2 :

-NH2 + 3 H2O2 -NO2 + 4H2O

Aniline oxidation with hydrogen peroxide; produce nitro benzene and water.

8. Substitution in Benzene ring of Aniline

• In benzene ring , amine group increase the density of Electron at Ortho, pera position. So the next group will attach to the benzene ring at the Ortho, pera position.

• Halogenations of Aniline:

• 2,4,6- tribromo aniline

• React fast

• It is very active. So the two ortho group and pera group attach at same time.

Nitration of Aniline:

Though -NH2 group is a ortho, pera indicator but, when it react with acid it

produce meta-Nitroaniline because of Anilinium ion.

• Sulphonation of Aniline:

Aniline react with Sulphuric acid and produce 4-amino benzene sulphonic acid.

Wgic gives ‘zwitter aion’ in aqueous solution.

Thank

you

Everyone