1. Structure and Properties a. Boiling points b. Pyrimidal structure

CHAPTER TWENTY-THREE: AMINES
1. Structure and Properties
a. Boiling points
b. Pyrimidal structure and chirality
c. Basicity (pKa conjugate acid is 10; pKa amine is 35-40)
o Trends among structural categories
2. Preparation
a. Via SN2 with Ammonia (not preparative)
b. Via SN2 via azide or cyanide followed by reduction with LAH
c. Via reduction of Nitro group with Sn/HCl
3. Reactivity
4. With Nitrous Acid HNO2 in H2SO4 (NO+)
o mechanism of formation
a. 3° aliphatic amines to form salts
b. 2° aliphatic amines to form N-nitrosamines R2N-N=O
c. 1° aliphatic amines to form diazonium ions RN2+ which immediately decompose
d. 1° aromatic amines to form diazonium ions which are stable enough to react
further
o Diazonium Ion Reactivity
1. Sandmeyer Reaction: CuCl and HCl, CuBr and HBr, CuCN
and KCN
2. Hydrolysis: H2O (formation of phenol)
3. KI
4. H3PO2
5. Hoffman Elimination:
Exhaustive methylation to 4° ammonium halide, reaction with Ag2O to form hydroxide
salt and β-elimination
a. Mechanism
b. Product selectivity: Hoffman’s rule: less substituted alkene formed
preferentially
LEARNING OUTCOMES:
 Formulate the optimal preparation method for a target organic amine.
 Predict the missing product and/or reactants in a chemical reaction involving amines.
 Predict the relative acidity of amines of various structures
 Devise a strategy for synthesizing substituted benzene given limitations of various
substitution reactions.
 Use curved-arrow formalism to depict the known mechanism of an organic reaction.
 Devise multi-step syntheses of molecular targets using comprehensive knowledge of
functional group transformations.
SAMPLE EXAM PROBLEMS:
1. Provide the structure of the missing reagents and/or products A and B in each of the
following reaction sequences: (8 points each)
+
N2
CN
H2
A
B
Ni
2. Rank the basicity of the following amines:
NH
A
N
B
________
Most basic
________
N
C
________
Least basic
3. Propose a sequence of steps to produce the product shown (on left) from benzene.
You may use any organic or inorganic reagents necessary.
OH

Download Report