Woodward Fieser Rules for UV spectrometry

* Brief description of Woodward Fieser Rules.
* Examples for all te 3 rules

1. Assignment on ‘Woodward Fieser Rules’
Advanced Pharmaceutical Analysis (PHR 410)

Submitted by,
Md. Azamu Shahiullah
Department of Pharmacy
BRAC University.
Assignment on ‘Woodward Fieser Rules’
Advanced Pharmaceutical Analysis (PHR 410)
Submitted to,
Ridwan Islam
Department of Pharmacy
BRAC University.
1


Department of Pharmacy
BRAC University.

2. 2


Index

1. Introduction
2. dwwadrFaR uil’lF Fvcl’
3.1 Woodward Fieser rule for Conjugated Dienes and Polyenes
3.2 Parent values and increments for different Substituents or Groups
3.3 Example of Woodward Fieser rule for Conjugated Dienes and Polyenes
4.1 deetPhmt uWy(ym moHy 4em fBC R og(hnomhnyt 1hm.egyl compounds.
4.2 Parent values and increments for different Substituents or Groups
4.3 Example of Woodward Fieser rule for α,β unsaturated hydrocarbon
5.1 Woodward Fieser rule for Aromatic compounds or Benzoyl derivatives.
5.2 Parent values and increments for Benzoyl Derivatives
5.3 Example of Woodward Fieser rule for Benzoyl derivatives

3. 1. Introduction
In 1945 Robert Burns Woodward gave certain rules for correlating λ
structure. In 1959 Louis Frederick Fieser modified these rules with more experimental data,
and the modified rule is known as Woodwar
and λmax for a given structure by relating the position and degree of substitution of
chromophore.



2. WOODWARD3 FIESER RULES
Each type of diene or triene system is having a certain fixed value at which absorption takes
place; this constitutes the Base value or Parent value
alkyl substituents or ring residue, double bond extendi
h( j1HB RBr etc are added to the basic value to obtain λ
According to Woodward’s rules the λ
λmax = Base value + Σ Su

In 1945 Robert Burns Woodward gave certain rules for correlating λmax
structure. In 1959 Louis Frederick Fieser modified these rules with more experimental data,
and the modified rule is known as WoodwartRFieser Rules. It is used to calculate the position
for a given structure by relating the position and degree of substitution of

FIESER RULES
Each type of diene or triene system is having a certain fixed value at which absorption takes
Base value or Parent value. The contribution made by various
alkyl substituents or ring residue, double bond extending conjugation and polar groups such
Br etc are added to the basic value to obtain λmax for a particular compound.
According to Woodward’s rules the λmax of the molecule can be calculated using a formula:
= Base value + Σ Substituent Contributions + Σ Other Contributions
3
max with molecular
structure. In 1959 Louis Frederick Fieser modified these rules with more experimental data,
Fieser Rules. It is used to calculate the position
for a given structure by relating the position and degree of substitution of

Each type of diene or triene system is having a certain fixed value at which absorption takes
. The contribution made by various
ng conjugation and polar groups such
for a particular compound.
of the molecule can be calculated using a formula:
bstituent Contributions + Σ Other Contributions

4. 4

There are three sets of rules
1. deetPhmtRuWy(ym moHy 4em 1eg0o)hnyt tWygy( hgt DeHbenes.
2. uem R og(hnomhnyt 1hm.egbH ‘eMDeogt(U
3. For Aromatic compounds or Benzoyl derivatives.

3.1 Woodward Fieser rule for Conjugated Dienes and Polyenes
a. Homoannular Diene:3 Cyclic diene having conjugated double bonds in same ring.

1
2
3
4
5
6

b. Heteroannular Diene:3 Cyclic diene having conjugated double bonds in different rings.

1
2
3
4
5
6
7
8
9
10

5. 5

c. Endocyclic double bond:3 Double bond present in a ring.

1
2
3
4
5
6

d. Exocyclic double bond: 3 Double bond in which one of the doubly bonded atoms is a
part of a ring system.

1
2
3
4
5
6
7
8
9
10
A B

Here Ring A has one exocyclic and endocyclic double bond. Ring B has only one endocyclic
double bond.
e. Double bond extending :3 When more double bonds are present other than conjugations.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
O
18
OH
19

6. 6

3.2 Parent values and increments for different Substituents or Groups
Parent Value
Acyclic conjugated dienes and Heteroannular conjugated dienes 215 nm
Homoannular conjugated dienes 253 nm
Acyclic trienes 245 nm
Increments
Each alkyl substitute or ring residue 5 nm
Exocyclic double bond 5 nm
Double bond extending conjugation 30 nm
Auxochromes
nl1( <(,$(
n/1( :=(,$(
nob*n.d( 2(,$(
n>1)( <=(,$(
nlolo;:( =(,$(

3.3 Example of Woodward Fieser rule for Conjugated Dienes and Polyenes
1. Example 1

                             (3E)-3,5-dimethylhexa-1,3-diene—ethane (1/2) 
Here,
Parent value for Acyclic conjugated diene = 215 nm

7. 7

ab4zb(/e%r5h5e59(id(1h,p(d9rhme9(85((on:(8,m(on2(?(5+5= 10 nm
So, λ
max would be = (215+10) nm = 225 nm
l%r9d#9m(#8be9(?())2(A(n(2(,$(

2. Example 2


                      4a,7,8,9-tetramethyl-2,3,4,4a,4b,5,6,8a-octahydrophenanthrene 
Here,
Parent value for Heteroannular conjugated diene = 215 nm

8. 8

Alkyl substitute or Ring residue = (5 x 4) nm = 20 nm
Exocyclic double bond (in respect of B ring) = 5 nm
So, λ
max would be = (215+20+5) nm = 240 nm
l%r9d#9m(#8be9(?()1=(A(n(2(,$((
3. Example 3


1,2,4b,10-tetramethyl-1,2,3,4,4b,5,6,7-octahydrophenanthrene 

9. 9

Here, Parent value Homoannular conjugated diene = 253 nm
Alkyl substitute or Ring residue = (5 x 6) nm = 30 nm
Exocyclic double bond (in respect with ring B) = 5 nm
Double bond extending conjugation = 30 nm
So, λ
max would be = (253+30+30+5) nm = 318 nm
Observed value would be = 318 + 5 nm

10. 10

4.1 Woodward Fieser rule for α,β 3 unsaturated Carbonyl compounds.
deetPhmtRuWy(ym moHy( ‘hg .y ypnygtyt ne ‘hH‘oHhny nIy 3Mhp e4 fBCRog(hnomhnyt ‘hm.egbH
compounds. In a similar manner to Woodward rules for dienes discussed previously, there is
base value to which the substituent effects can be added and the λmax can be calculated using the
formula:

λmax = Base value + Σ Substituent Contributions + Σ Other Contributions




Acyclic Enones

Acyclic Dienone

53membered cyclic
α
β
α β
α β γ ȣ α
β
γ
ȣ

11. 11


63membered cyclic


4.2 Parent values and increments for different Substituents or Groups
Parent Value
α,β Rog(hnomhnyt h‘b‘HW‘ em (Wp MyM.ymyt
ring ketone
215 nm
α,β Rog(hnomhnyt 4W,y MyM.ymyt mWg) Eynegy 202 nm
α,β Rog(hnomhnyt hHtyIbty
207 nm
Increments
Each alkyl substitute or ring residue
At position α
10 nm
At position β 12 nm
At γ position and higher position 18 nm
Each Exocyclic double bond 5 nm
Double bond extending conjugation 30 nm
Homoannular conjugated diene 39 nm
Auxochromes α β γ
Rwβ αO α6 O6
RwF αO α6 A@
R’F R DO R
Rw1w1βα γ γ γ

12. 12

4.3 Example of Woodward Fieser rule for α,β unsaturated hydrocarbon
1. Example 1
  
 
 
 
           4a,7,8,9-tetramethyl-4,4a,4b,5,6,7,8,8a-octahydrophenanthren-2(3H)-one 

Here,
Parent value for
α,β unsaturated cyclohexen base = 215 nm

Double bond extending conjugation = 30 nm
Exocyclic double bond (in respect to ring B) = 5 nm
α
β γ
ȣ

13. 13

Alkyl substitute or Ring residue at β position = 12 nm

Alkyl substitute or Ring residue at ȣ position = (18 x 2) nm= 36 nm
So, λ
max would be = (215+30+5+12+36) nm = 298 nm
w.(ym,yt ,hHoy PeoHt .y ? s3D A R O gM
2. Example 2


Here,
Parent value for
α, β unsaturated 6 membered enone = 215 nm

α
β
γ
ȣ
β

14. 14

Double bond extending conjugation = 30 nm
Alkyl substitute or Ring residue at
β position = 12 nm

Alkyl substitute or Ring residue at
ȣ position = 18 nm

Exocyclic double bond (in respect to ring A) = 5 nm

So, λ
max would be = (215+30+5+12+36) nm = 298 nm
w.(ym,yt ,hHoy PeoHt .y ? s3D A R O gM




β
ȣ

15. 15

3. Example 3

1-methyl-1,4,5,6,7,7a-hexahydro-2H-inden-2-one 
Here,
Parent value for
α, β unsaturated 5 membered enone = 202 nm

β ring residue = (12 x 2) nm = 24 nm
Exocyclic double bond (in respect of ring B) = 5 nm
So, λ
max would be = (202+24+5) nm = 231 nm
l%r9d#9m(#8be9(7iebm(%9(?():3(A(n(2(,$(((
α β
β

16. 16

5.1 Woodward Fieser rule for Aromatic compounds or Benzoyl derivatives.
5.2 Parent values and increments for Benzoyl Derivatives
Parent Value
X = alkyl / ring residue, ArCOR 246 nm
X = H, ArCHO 250 nm
F(?(l;(G(ln8b4zb*(adol2H, ArCO2R 230 nm
Increments
R = alkyl / ring residue o, m = 3 nm
p = 10 nm
1(?(l;(G(ln8b4zb( o, m =7 nm
p = 25 nm
R = NH
2
o, m = 23 nm
p = 58 nm


5.3 Example of Woodward Fieser rule for Benzoyl derivatives

1. Example 1

                                    1-(5,6,7,8-tetrahydronaphthalen-1-yl)ethan-1-one 
 
 

17. 17

Here,
Parent value for Benzoyl group (aliphatic methyl group) = 246 nm


Auxochrome at Ortho Position = 3 nm

Auxochrome at Meta position = 3 nm

So, λ
max would be = (246+3+3) nm = 252 nm
Observed value would be = 252 + 5 nm

18. 18

2. Example 2

                                        3,4,5-trihydroxybenzoic acid 
Here,
08d9,5(#8be9(6id(.9,/izb(pdie'(Binab4zbC(?():=(,$
Auxochrome –OH at Meta position = (7 x 2) nm = 14 nm
Auxochrome –OH at Pera position = 25 nm

19. 19

So, λ
max would be = (230+25+14) nm = 269 nm
l%r9d#9m(#8be9(7iebm(%9(?()<0(A(n(2(,$(((
3. Example3


                                                         methyl 3-nitrobenzoate 
Here,
08d9,5(#8be9(6id( r59d(6e,t5hi,8bh5z(Bnl1C(?():=(,$
There is no value listed for a Meta nitro group.
So, λ
max would be more than 230 nm.