3. WOODWARD FIESER RULES
For
α,β Unsaturated Carbonyl compounds
• Acyclic or six membered cyclic α,β Unsaturated Ketone compounds
basic λmax value is --- 215 nm
Acyclic ketone compound Six membered cyclic ketone compound
• Five membered cyclic α,β Unsaturated Ketone compounds
basic λmax value is --- 202 nm
• Acyclic or cylic α,β Unsaturated Aldehyde compounds
basic λmax value is --- 207 nm
O
O
O
O
4. WOODWARD FIESER RULES
For
α,β Unsaturated Carbonyl compounds
Increments or substituents:
• Ring Residue or Alkyl substitute at each position of double bond;
•
• β position have one alkyl substituent - 12nm
• β position have one alkyl substituent - 12nm
δ position have one alkyl substituent -18nm
δ position have one -OH substituent - 50nm
O
O
OH
5. WOODWARD FIESER RULES
For
α,β Unsaturated Carbonyl compounds
• Exocyclic double bond basic value – 05nm
The double bond present in the out side of the ring with conjugation is called
Exocyclic double bond.
Only one exocyclic double bond No exocyclic One exocyclic
• Extended conjugated Double bond basic value : 30nm
The double bond is a part of the conjugation which is extension the
conjagated system.
One Extended double bond Only one extended Only one extended
double bond double bond
O
A B
O
A
B
O
O
O
6. WOODWARD FIESER RULES
For
α,β Unsaturated Carbonyl compounds
• Homoannular conjugated diene basic value – 39nm
The Conjugated double bonds present in the same ring is called Homoannular
Homo annular is present No Homoannular
O
O
7. WOODWARD FIESER RULES
For
α,β Unsaturated Carbonyl compounds
Examples:
1.
Acyclic α,β Unsaturated ketone compounds basic value – 215nm
Alkyle substitute at only δ position – 1 X 18 = 18nm
Extended conjugated double bond – 1 X 30 = 30nm
-----------------
λmax value = 263nm
------------------
2. cyclic α,β Unsaturated ketone compounds basic value – 215nm
Alkyle substitute at only β position – 1 X 12 = 12nm
Alkyle substitute at only δ position – 1 X 18 = 18nm
Exocyclic double bond – 1 X 05 = 05nm
Extended conjugated double bond – 2 X 30 = 60nm
Homoannular conjugated diene -- 1 X 39 = 39nm
-----------------
λmax value = 349nm
------------------
O
O
