The document discusses the structural elucidation of quercetin, detailing its sources, molecular structure, and characteristics. It highlights the results of various spectral analyses that confirm the presence of hydroxyl, carbonyl, and aromatic groups, and elaborates on the synthesis methods of quercetin. The conclusion asserts that quercetin's structure is validated through comprehensive spectral data.

1. Structural Elucidation Of Quercetin
Presented By:
•Gandham Malasree
•M Pharmacy
•Regd no: 620209502002
•Dept of Pharmaceutical Chemistry
AU College Of Pharmaceutical Sciences,

2. INTRODUCTION:
 Quercetin is the aglycone form of a number of other flavonoid glycosides, such
as rutin and quercitrin.
 Quercetin is one of the most widely distributed natural pigment and most abundant dietary
flavonoid.
 It occurs as the glycosidic quercetin in the barks of Quercus tinctoria.
 It is naturally occurring polar auxin transport inhibitor.
Sources: Citrus fruit
Buck wheat
Red onions
Red roses
Apples
Honey
Tomatoes
Oak bark

3. STRUCTURE OF QUERCETIN:
Molecular formula: C15
H10O7
Molecular weight: 302gm

4. CONSTITUTION:
• When quercetrin is hydrolysed with HCl it gives quercetin and L - Rhamnose
1. Presence of 5 –OH groups :
• Quercetin forms penta acetyl & penta methyl derivatives, thus the presence of 5 –OH groups are
indicated.
SOLUBILITY
• It is soluble in sodium hydroxide,

5. 2)
3:3’:4’:5:7 – penta hydroxy flavanol
KOH
boiling
6 – hydroxy , ω:2:4- trimethoxy acetophenone

6. 3) Synthesis Of Quercetin
1. Kostaneckis synthesis
1 2
4 3
5
Trimethoxy
phenol
Dimethoxy
benzaldehyde

7. 2. Robinsons method:
Tri hydroxy
acetophenone
1
2
Anhydride

8. Structural relationship between flavanols (quercetin), anthocyanins(cyanidine
chloride) and catechins :
1. They produce same degradation product when fused with KOH

9. 2.

10. • Bauer & his associates in 1954, converted penta acetate of quercetin into cyanidine chloride by
means of LiAlH4
.
3.

11. Spectral Values Of Quercetin
UV spectrum: λmax = 425 nm
IR spectrum: Group Absorption range Strectching/ Bending
2º OH 3282 cm-1 Stretching
C=O 1743 cm-1 Stretching
C=O 1666 cm-1 Stretching
C=C 1610 cm-1 Stretching
-OH 1517 cm-1 Bending
-OH 1430 cm-1 Bending
-OH 1358 cm-1 Bending
C – O 1210 cm-1 Stretching
C – O 1094 cm-1 Stretching
C – O 1001 cm-1 Stretching
C=C 929 cm-1 Bending
C=C 882 cm-1 Bending
C – H 808 cm-1 Bending

12. NMR SPECTRUM
δ - ppm

14. MASS SPECTRUM

15.  Presence of 5,7,3’4’ tetrahydroxy flavonol aglycones were confirmed by the UV spectra.
 The presence of hydroxyl, carbonyl, aromatic and ether group were confirmed by the ir spectra.
 The presence of two meta coupled aromatic protons at h-6,h-8, position confirms the 5,7 di-
substituted ring a were confirmed by H1 NMR.
 The presence carbon atoms were confirmed by C13NMR spectrum .
 Quercetin was confirmed by the all spectral analysis.
CONCLUSION