Flavones are yellow plant pigments that occur either freely or as glycosides. They are hydroxylated derivatives of 2-phenyl-4-chromone. Flavones are yellow solids that are soluble in water and ethanol. Their structure was determined to be C15H10O2 based on analytical data and molecular weight determination. When boiled with alcoholic KOH, flavones produce a mixture of four compounds: salicylic acid, acetophenone, o-hydroxyacetophenone, and benzoic acid, explaining their core structure. Several methods can be used to synthesize flavones, including Kostanecki's, Robinson's, modified Claisen's condensation, Baker-Ven

1. Flavones
By :- Kakadiya dipesh

2. Defination
• Flavones are yellow pigments which occur in
plant kingdom either in the free state or as
glycosides or assosiated with tannins.
• These are also known as anthoxanthins

3. • Chemically , flavones are hydroxylated
derivatives of 2-phenyl-4-chromone.

4. Properties of flavones
1. Yellow solids.
2. Soluble in water ,ethanol ,and dilute acid.
3. Precipetted by Lead salt.
4. With Ferric chloride , flavones gives dull
green or red brown colour.

5. General methods for the elucidation
of structure of flavones
• From analytical data and molecular weight
determination, the molecular formula of flavone has been
found to be C15H10O2.
• When acetylated, flavone does not yield any acetyl
derivative, indicating the absence of any –OH group.
•When fused with KOH, it yields phenol & benzoic acid.

6. •When flavone is boiled with alcoholic KOH solution, it
yields a mixture of four compound, salicylic acid(II),
acetophenone (III), o-hydroxyacetophenone (IV) and
benzoic acid (v).

7. •The formation of above products could be explained by
assuming the structure (I) as the correct structure of
flavone.

8. • On reaction with alchoholic KOH , the pyrone ring of
flavone are open to produce
o-hydroxydibenzoylmethane (IA) which than
undergoes scission in two different ways to yeilds
two pairs of products.

9. Synthesis of flavone
• Kostanecki’s synthesis :-

10. Robinson’s synthesis :-

11. •Modified claisen’s condensation :-

12. •Baker-Venkatraman Synnthsis :-

13. •Wheeler’s synthesis :-