ORGANIC CHEMISTRY 354

AMINES

NOMENCLATURE

STRUCTURE

PHYSICAL PROPERTIES

BASICITY

AMINES

DERIVATIVES OF AMMONIA

ORGANIC BASES

OCCUR WIDELY IN NATURE

CLASSIFICATION

PRIMARY (RNH₂)

SECONDARY (R₂NH)

TERTIARY (R₃N)

DIFFERENT THAN ALCOHOL CLASSIFICATION

NOMENCLATURE

PRIMARY AMINES

SECONDARY AMINES

TERTIARY AMINES

ARYLAMINES

HETEROCYCLIC AMINES

STRUCTURE

NITROGEN IS sp³ HYBRID

TETRAHEDRAL GEOMETRY

IF THREE DIFFERENT GROUPS

MOLECULE IS CHIRAL

MOST SUCH AMINES CAN'T BE RESOLVED DUE TOINVERSION

TAKES ABOUT 6 KCAL/MOL

PHYSICAL PROPERTIES

CAN HYDROGEN BOND

LOW MOLECULAR WEIGHT AMINES ARE WATER SOLUBLE

BOILING POINTS ARE HIGHER THAN ALKANES

CH₃CH₂NHCH₂CH₃

MW = 71, BP = 56^o

CH₃CH₂CH₂CH₂CH₃

MW = 72, BP = 36^o

ODOR

LOW MOLECULAR WEIGHT FISH-LIKE AROMA

DIAMINES REALLY BAD AROMA

BASICITY

MUCH MORE BASIC THAN ALCOHOLS

pK_a OF CONJUGATE ACIDS (RNH₃⁺) ABOUT 10-11

pK_a OF NH₄⁺ ABOUT 9

ALIPHATIC AMINES SLIGHTLY MORE BASIC THAN AMMONIA

BOTH INDUCTIVE AND SOLUBILITY EFFECTS AFFECT BASICITY (HARD TO COMPARE)

ARYLAMINES ARE WEAKER BASES THAN ALIPHATIC AMINES.

ELECTRON DONATING GROUPS ON THE RING INCREASE BASICITY.

AMIDES EVEN LESS BASIC.

WHY?

DUE TO AMINE BASICITY

• CAN USE EXTRACTION TO SEPARATE
• HAVE A SIMPLE CHEMICAL TEST