WOODWARD– FIESER RULES.pdf

WOODWARD– FIESER RULES

1. WOODWARD –FIESER
RULES
PRESENTING BY-INDRAJIT SAMANTA
ENROLLMENT ID-2022-518-002
M.PHARM; 1ST YEAR; 2ND SEMISTER
DEPARTMENT OF PHARMACEUTICAL CHEMISTRY
SCHOOL OF PHAMACEUTICAL EDUCATION & RESEARCH,
JAMIA HAMDARD.
SUBMITTED TO-Dr.NADEEM SIDDIQUI
ASSOCIATE PROFESSOR, DEPARTMENT OF
PHARMACEUTICAL CHEMISTRY;
SCHOOL OF PHAMACEUTICAL EDUCATION & RESEARCH,
JAMIA HAMDARD.

2. LIST OF
CONTENTS
Introduction
WOODWARD -FIESER RULES
Woodward -Fieserrules for
Conjugateddienes
Woodward -Fieserrules for α,β
unsaturated Carbonyl compounds
Woodward -Fieserrules for
Aromatic compounds or Benzoyl
derivatives

3. Introduction
a.In1945RobertBurnsWoodwardgavecertainrulesforcorrelatingλstructure.
b.In1959LouisFrederickFiesermodifiedtheseruleswithmoreexperimental
data,andthemodifiedruleisknownasWoodwardFieserruleandλmaxfora
givenstructurebyrelatingthepositionanddegreeofsubstitutionof
chromophore.Woodwardrulesworkwellfordienesandpolyeneswithupto4-
doublebondsorless.
c.Thesesetsofrulestocalculatethewavelengthofmaximumabsorption(λmax)
ofacompoundintheultraviolet-visiblespectrum,basedempiricallyhavebeen
calledtheWoodward-FieserRulesorWoodward’sRules.
d.Thismaybediffersfromobservedvalueby4-5nm.
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4. 4 Presentation title 20XX
•Eachtypeofdieneortrienesystemishavingacertainfixedvalueatwhichabsorptiontakesplace;this
constitutestheBasevalueorParentvalueThecontributionmadebyvariousalkylsubstituentsorringresidue,
doublebondextendingconjugationandpolargroupssuchas–Cl,-Bretcareaddedtothebasicvaluetoobtain
λmaxforaparticularcompound.AccordingtoWoodward’srulestheλmaxofthemoleculecanbecalculatedusing
aformula:
λmax=Basevalue+Σsubstituentcontribution+ΣOtherContributions
There are three sets of rules
•1.Woodward-Fieser rule for Conjugated dienes and polyenes.
•2. For -unsaturated Carbonyl compounds.
•3.For Aromatic compounds or Benzoyl derivatives.
WOODWARD-FIESER RULES

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❖HomoannularDiene:-Cyclic diene having conjugated double bonds in
same ring.
❖HeteroannularDiene:-Cyclic diene having conjugated double bonds in
different rings.
Woodward -Fieserrule for
Conjugated Dienes

6. Woodward -Fieserrule
❖Endocyclic double bond:-Double bond present in a ring.
❖Exocyclic double bond: -Double bond in which one of the doubly
bonded atoms is apart of a ring system. Here Ring A has one exocyclic
and endocyclic double bond. Ring B has only one endocyclic double
bond.
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7. Woodward -Fieserrule
•Acyclic diene:
•Double bond extending conjugation:
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8. Woodward -Fieserrule
❖Woodward -Fieserrules are used for calculation of absorption maximum λmax
wavelength in conjugated dienes and trienes
The diene absorption is influenced by its structure
✓Woodward gave rules for calculating λmaxwhich was improved by Fieser.
✓Unlike the base value 217 nm used for predicting the λmaxvalues (1,3-butadiene)
Woodward -Fieserfix this value at 214 nm.
✓Calculated and experimental values of λmaxmatch within 5 nm
✓In case of acyclic diene such as myrcene there is only alkyl i.e., C-substituent on
the dienes system
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9. WOODWARD_FIESER RULE FOR
CONJUGATED DIENES AND TRIENES
❖Conjugated diene: Organic compound containing two or more double bonds each separated
from other by a single bond.
❖Base/Parent value: It means that each type of diene or triene system is having a certain fixed
values at which absorption takes place; this constitutes the Base value or Parent value.
❖The contribution made by various alkyl substituents or ring residue, double bond extending
conjugation and polar groups such as -Cl,-Br etc. are added to the base value to obtain λmaxfor
a particular compound.
❖Longer the conjugated system greater the wavelength of absorption maximum.
❖According to Woodward’s rules the λmaxof the molecule can be calculated using a formula:
λmax= Base value + Σ Substituent Contributions + Σ Other Contributions
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10. Table A: Parent values and increments for different
substituents /groups for calculating maximum wavelength
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12. Example 1:
•Base value for Heteroannularconjugated diene = 214 nm
•3 Ring residues (3×5) = 15 nm
•1 Exocyclic double bond = 5 nm
λmax = 234 nm
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13. Example 2:
•Base value for homoannularconjugated diene = 253 nm
•3 Ring residues (3×5) = 15 nm
•1 Exocyclic double bond = 5 nm
λmax = 273 nm
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14. EXAMPLE:3
•Base value for Heteroannularconjugated diene = 214 nm
•3 Ring residues (3×5) = 15 nm
•1 Exocyclic double bond = 5 nm
λmax = 234 nm
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15. EXAMPLE:4
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Base value for Heteroannularconjugated diene = 214 nm
3 Ring residues (3×5) = 15 nm
1 Exocyclic double bond = 5 nm
-OR (Alkoxy group) = 6 nm
λmax = 240 nm

16. EXAMPLE:5
Base value for Homoannularconjugated diene = 253 nm
5 Ring residues (5×5) = 25 nm
2 Double bond extending conjugation (2×30) = 60 nm
3 Exocyclic double bond (3×5) = 15 nm
-OCOCH3 = 0 nm
λmax = 353 nm
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17. EXAMPLE
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18. WOODWARD -FIESER RULE FOR α,β -
UNSATURATED CARBONYL COMPOUNDS
(ENONES)
•Woodward and Fieserframed certain empirical rules for estimating the
absorption maximum for α,β-unsaturated carbonyl compounds. The
rules later modified by Scott.
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19. Table C: Parent values
and increments for
different substituents
or groups for
calculating maximum
wavelength

20. Values for substituents or groups:
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21. Values for Solvent content:
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22. Example 1:
22
α, β-unsaturated acyclic ketone = 215 nm
2 alkyl groups at β-position (2×12) = 24 nm
λmax = 239 nm

23. Example 2:
23
Base value for α, β-unsaturated six membered ring ketone
= 214 nm
β-ring residue (1×12) = 12 nm
δ-ring residue (1×18) = 18 nm
1 Double bond extending Conjugation (1×30) = 30 nm
1 Exocyclic double bond = 5 nm
λmax = 279 nm

24. Example 3:
24
base value for α, β-unsaturated six
membered ring ketone = 215 nm
Substitution of alkyl groups at α-
position = 10 nm
Ring residue at β-position = 12 nm
λmax = 237 nm

25. Example 4:
25
Basic value = 215 nm
ά-ring residue = 10 nm
δ-ring residue = 18 nm
1 Exocylicdouble bond = 5 nm
1Homoannular conjugated diene = 39 nm
1 Double bond extending conjugation = 30 nm
λmax = 317 nm

26. Examples:
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27. WOODWARD_FIESER RULEFORCYCLIC
DIENES(orAROMATICCOMPOUNDS)
Like Woodward fieserrules, Scott devised a set of rules for
calculating the absorption maximum for the derivatives of
Acyl benzenes.
These rules help in estimating the position of absorption
maximum (λmax) in ethanol in a number of mono substituted
aromatic ketones, aldehydes, acids, and esters.
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28. Table C: Parent values and increments
for different substituents/groups for
calculating maximum wavelength
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29. Values for substituents or groups:
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30. Example 1: Solution:
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Base value for Aromatic ketone = 246 nm
Hydroxyl group at meta position = 7 nm
Hydroxyl group at para position = 25 nm
λmax = 278 nm

31. Example 2: Solution:
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Base value for Ar-COOH = 230 nm
Hydroxyl groups at meta positions (2×7) = 14 nm
Hydroxyl group at para position = 25 nm
λmax = 269 nm

32. Example 3: Solution:
Base value = 246 nm
•Ring residue = 3 nm
•-OCH3 at paraposition = 25 nm
λmax = 274 nm
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33. Examples:
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34. FIESER-KUHN RULE
If the number of conjugated double bonds is more than 4, the Woodward
and Fieserrules may not be applicable and hence Fieserwith Kuhn has
derived an equation for predicting the λmax.
a.M = No. of alkyl substituents,
b.N = No. of conjugated double bonds,
c.Rendo= No. of rings with endocyclic double bonds,
d.Rexo= No. of rings with exocyclic double bonds,
Equation:
λmax= 114 + 5(M) + n(48-1.7n) -16.5 Rendo-10 Rexo
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35. FIESER-KUHN RULE
•εmax = (1.74 x 104) y
Where,
•εmaxis the maximum absorptivity
•y is the number of conjugated double bonds
•We can use this equation to calculate wavelength of maximum absorbance (λmax) and the
•maximum absorptivity (εmax) for polyene such as β-carotene, Lycopheneetc.
•Let us take β-carotene as an example. The observed λmaxof β-carotene is 452 nm, while theobservedεmaxis 15.2
x 104
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36. Example:1
No. of alkyl substituents = 10,
No. of rings with endocyclic
double bond=2
λmax=114+5(M) + n(48-1.7n) -
16.5 Rendo-10 Rexo
λmax= 114 + 5(10) +11(48-
1.7×11) -(16.5×2) -(10×0) = 453.3
nm

37. Steric Inhibition of
Resonance
1) In alkenes, trans
isomers exhibit absorption
at longer wavelength
and high intensity.
(2) Woodward rules are
applicable only if there is
no strain around
chromophore.
(3) If calculated and
experimental values of
λmaxdo not match,
one can say that the
molecule must have some
strain.
(4) Thus UV can be used
indirectly to determine if
the molecule
has any strain
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38. REFERENCES
•1) Donald L. Pavia, Gary M. Lampman, George S. Kriz, “ Spectroscopy”, published by Cengage
Learning, 2010. Pp. (379-387)
•2) SHARMA Y.R., “Elementary Organic Spectroscopy”, published by S. Chand & Company Ltd. 1st
edition, 2006. Pp. (31-49)
•3) CHATWAL G.R., ANAND S.K., “Instrumental Methods Of Chemical Analysis”, published by
Himalaya Publishing House, 5th edition, 2008. Pp. ( 2.162-2.167)
•4) KALSI P.S., “A Text Book Of Organic Spectroscopy”, published by NEW AGE INTERNATIONAL
PUBLISHERS, 6th edition. 2007. Pp. (40)
•5) RAJASHEKARAN, “A Text Book Of UV-Visible and Infrared Spectroscopy”, Pp. (88-100)
•6) Woodward, Robert Burns (1941). "Structure and the Absorption Spectra of α,β-Unsaturated
Ketones". J. Am. Chem. Soc. 63(4): 1123. doi:10.1021/ja01849a066.
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39. continue...
➢Woodward, Robert Burns (1941). "Structure and the Absorption Spectra of α,β-Unsaturated Ketones".J. Am. Chem.
Soc.63(4): 1123.doi:10.1021/ja01849a066.
➢^Louis F. Fieser; Mary Fieser; Srinivasa Rajagopalan (1948). "Absorption Spectroscopy and the Structures of the
Diosterols".J. Org. Chem.13(6): 800–6.doi:10.1021/jo01164a003.PMID18106021.
➢^Jump up to:
abcde
Mehta, Akul(5 Aug 2012)."Ultraviolet–Visible (UV–Vis) Spectroscopy –Woodward–FieserRules
to Calculate Wavelength of Maximum Absorption (Lambda-max) of Conjugated Carbonyl Compounds".
PharmaXChange.info.
➢^Neil Glagovich(2007-07-19)."Woodward's Rules for Conjugated Carbonyl Compounds".Central Connecticut State
University. Archived fromthe originalon April 10, 2008. Retrieved2008-05-05.
➢^Jump up to:
ab
William Reusch."UV–Visible Spectroscopy".VirtualTextof Organic Chemistry.Michigan State
University.
➢^Neil Glagovich(2007-07-19)."Woodward–FieserRules for Dienes".Central Connecticut State University. Archived
fromthe originalon April 10, 2008. Retrieved2008-05-05.
➢^Spectroscopic Determination of Organic Compounds, 5th Edition, Silverstein, Bassler, Morrill 1991
➢^Organic spectroscopyWilliam Kemp
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