This document provides an overview of flavonoids including their introduction, classification, isolation, purification, and methods for structural determination. Flavonoids are polyphenolic plant secondary metabolites with a C6-C3-C6 carbon skeleton found in flowers, leaves, bark, fruits, grains and nuts. They can be isolated from plant material by extracting with hot water or alcohol. Purification involves fractional crystallization or separation in solvent mixtures. Structural determination of flavonoids is done by observing their degradation products when fused with alkali, which produces identifiable phenols and aromatic acids.

1. Flavonoids
Presented by :- Akshaykumar B. Kadam
M.Pharm 1st year
Dept. P’Chemistry
R.C.P. Kasegaon.
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2. Content
 Introduction
 Classification
 Isolation And Purification
 General method of structural determination
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3. INTRODUCTION :-
 Flavonoids are group of polyphenolic compound, and they are a
class of plant secondary metabolites
 The flavonoids are possessing 15 carbon atoms; 2 benzene ring
joined by a 3 carbon chain having carbon skeleton C6 – C3 - C6.
They are plant pigments and having polar nature, soluble in
methanol and water.
 Flavonoids are found in higher vascular plants,particulary in flowers,leaves
and barks.Also in fruits ,grains and nuts.
OCCURRANCE:-
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4. Flavonoids
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5. Classifications -
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6. GENERAL METHOD OF ISOLATION:-
Plant material,
(Flavones /Flavonol)
Extract hot
water Aqueous
extract PPT
Lead acetate
Filtration
Remove tannins
Aqueous phase
Acidified with HCLSugar free
(Flavones /Flavonol)
Extract with alcohol
Alcoholic phase
(Flavones /Flavonol) Flavonoids
Fractional
crystallization
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7. Purification of flavonoids :-
Dried plant material is extracted with either 70% or 80 % Methanol
Aq. Extract is then concentrated to a small volume and filtered if
necessary
An aliquol of this concentration should be applied on whatman filter paper no. 3
Separation of flavones carried out in the solvent mixture BAW (4:1:5)
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8. Individual bands are eluted and concentrated
Further fraction in water, 5% acetic acid .
Purified in n- butanol – ethanol – water (4:1:2.2)
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9. General method of determination flavones:-
On fusion with alkali, flavones are degraded to a phenol and aromatic acids.
e.g.-
Flavones Phenol Aromatic acid
alkali
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10. 1. Salicylic acid
2.Acetophenone
3. Ortho-hydroxy Acetophenone
4.Benzoic acid
Flavones on boiling with KOH gives 4 different product -
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11. Flavones on boiling with KOH gives 4 different
product -
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