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Amines
Alcohols Phenols Ethers Thiols Dissulfides Amines
-O- -S- -N-
OC
Alkanes Alkenes Alkynes Aromatics
Aldehydes Ketones Acids Esters Anhydrides Amides
OC-N
OC-O
Hydrocarbons
All Classes of Organic Compounds
Functionalized Hydrocarbons
Halides
F,Cl,Br O,S,N
OC
Amines - “Derivatives of Ammonia”
ethylamine diethylamine triethylamine
Classification by the number of attached groups
H
N HH
H
N HH
H
N HH
H
N HH
a “primary” amine a “secondary” amine a “tertiary” amine
H
N HH
H
Quartenary Ammonium Ions
CH2CH3
N CH2CH3CH3CH2
CH2CH3
ammonium ion
“tetraethyl ammonium…..”
(part of a name)
H
N HH
[ ]
a “quaternary” ammonium salt
NR
N
H
N
N
H
N
N
N
N
H
N
N
Cyclic Amines
“ ”
pyrrolidine
imidazole
pyrimidine
purine
Amines - Classification
Classification by the type of attached groups
aromatic amines
aliphatic aminesCH2 NH
H3C CH2H3C
H3C NH2
NH
H
NH2
N
H
H
NH2
Amines - Nomenclature
Amines containing simple groups are named with common nomenclature.
Simple groups include: Unbranched alkyl groups: methyl, ethyl, propyl, butyl, …., decyl Branched 3- and 4-carbon alkyl groups: isopropyl, isobutyl, s-butyl, t-butyl Unsubstituted cycloalkyl groups: cyclohexyl and cyclopentyl
NCH3 CH2CH3ethylmethylamine
N CHCH3
H
H
CH3isopropylamine
cyclohexylmethylamine
N HCH3
NCH3 CH2
CH3CH3
ethyldimethylamine
H
2º 1º
2º 3º
Amines - Nomenclature
NH2 NH2
CH3
aniline 4-methyl aniline p-methyl aniline
NH
H3C
N-methyl aniline
Amines - Nomenclature
H2N CH2 CH2 CH2 COOH
CH3 CH CH2 CH2 OH
NH3C CH3
4-aminobutanoic acid
3-(dimethylamino)-1-butanol
3,N-dimethyl-2-pentanamineCH3 CH CH CH2 CH3
HNCH3
CH3
Worksheet on
Amines
CH3 NCH2CH2CH3
CH CH3
CH3
Br
N
CH3CH2CHCH2CHCH3
CH2CH3H
Br NCH2CH2CH3
H
amine
-3-hexanamine
-aniline
1.
2.
3.
Amines - Heterocyclic Nitrogen Compounds
Amines - Physical Properties
NH
HR N
H
RR N
R
RR
1º amine 2º amine 3º amine
1) Both 1º and 2º amines exhibit strong secondary forces (hydrogen bonding), primary amines slightly more so than secondary amines.
2) Hydrogen bonding involving nitrogen atoms is weaker than that involving oxygen atoms because nitrogen is less electronegative than oxygen.
a) The secondary forces in primary and secondary amines are weaker than those in alcohols.
b) The strength of N-H hydrogen bonding in amines is comparable to the dipole-dipole forces in aldehydes and ketones.
Amines - Physical Properties
1) Tertiary amines do not possess an N-H bond and therefore exhibit only weak secondary forces.
2) The strength of the weaker secondary forces in tertiary amines is comparable to those in ethers and hydrocarbons.
3) Tertiary amines have melting and boiling points considerably lower than those of primary and secondary amines, comparable to those of ethers and hydrocarbons.
Amines - Physical Properties
NH
HR N
H
RR N
R
RR
1º amine 2º amine 3º amine
Amines - Physical Properties
Amines - Physical Properties
Amines - “Basic” Compounds
When dissolved in water, amines generate hydroxide ions.
NR
RR
R=H, alkyl, aryl
NH
RR + HO-+ H2O R
+
The product of the reaction is a salt and it is named from the name of the starting amine.
NH
HCH3 N
H
H+ HO-+ H2O H
+CH3
methylamine a solution of methylammonium hydroxide
NH4+
Acidities and Basicities of Organic Compounds
Compound Structure [OH-] [H3O+] pH Ionization (%)
sodium hydroxide NaOH 1.0 x 10-1 1.0 x 10-13 13.00 100
methyl amine CH3NH2 6.8 x 10-3 1.5 x 10-12 11.82 6.8
aniline C6H5NH2 6.5 x 10-6 2.4 x 10-9 8.62 0.0065
water H2O 1.0 x 10-7 1.0 x 10-7 7.00 0.0001
ethanol CH3CH2OH 1.0 x 10-7 1.0 x 10-7 7.00 0.0001
phenol C6H5OH 3.0 x 10-9 3.3 x 10-6 5.48 0.0033
acetic acid CH3COOH 7.7 x 10-12 1.3 x 10-3 2.89 1.3
benzoic acid C6H5COOH 4.0 x 10-12 2.5 x 10-3 2.60 2.5
hydrochloric acid HCl 1.0 x 10-13 1.0 x 10-1 1.00 100
Values for 0.10 M aqueous solution
Amines - “Basic” Compounds
An amine may be reacted with a strong acid to quantitatively yield an amine salt.
NH
HCH3 N
H
H Cl-+ HCl H
+CH3
methylamine methylammonium chloride
NH3 + HCl NH4Cl
Ammonia may be reacted with a strong acid to quantitatively yield an amonium salt.
ammonia hydrogen ammonium chloride chloride
Amines - Properties of Amine Salts
NH
HCH3 N
H
H Cl-+ HCl H
+CH3
methylamine methylammonium chloride
mp -94ºC, bp -6ºC mp 232ºC
The melting and boiling points of amine salts are much higher than those of the corresponding amines.
All amine salts are solids at room temperature.
Amine salts are much more soluble in water than amines due to the strong interaction of water molecules with ions.
Amines are soluble in neutral or lower pH where they are converted into their salt forms.
Amines - Amine Based Drugs
HO CHCH2NH
CH3HCl
phenylephrine hydrochlorideNEOSYNEPHRINE
R-NH
CH3H
+
Cl-
phenylephrine hydrochloride NEOSYNEPHRINE
CH2CH2
N
H
CH3
HClHO
procaine hydrochloride NOVACAINE
diphenehydramine hydrochloride BENADRYL
H2N
C
O
OCH2
CH2N
CH2CH3
CH2CH3
HClCH
OCH2
CH2N
CH3
CH3HCl
3-(2-(methylamino)ethyl)phenol hydrochloride
2-(diethylamino)ethyl 4-aminobenzoate hydrochloride 2-(benzhydryloxy)-N,N-dimethylethanamine hydrochloride
Biologically Interesting Amines
Biologically Interesting Amines
Interconversion of Amine Forms
H+
Cl-
Cocaine (Free Base) Cocaine hydrochloride
HCl
Base
Worksheet on
Amines
CH3 NCH2CH2CH3
CH CH3
CH3HCl
aminepropylisopropyl methyl
4.
NCH2
CH3
CH3
CH2CH3
H
Cl
NaOH
dimethylpropyl ammonium chloride
5.
NCH2
CH3
CH3
CH2CH3
CH2
Cl
CH2
CH3
NaOH
6.