natural product under terpenoids.and citral is an acyclic mono terpenoids

1. citral
P.Bonehoeffer

2. what is citral?
 Citral, or 3,7-dimethyl-2,6 octadienal is either a pair ,or a
mixture of terpenoides with the molecular formula
C10H16O
 Chemically, citral is a mixture of two aldehyde that have
the same molecular formula but different structures.
 The two compunds are found in citral which are double
bond isomers.
The E- isomer is know as geranial or citral A
The Z- isomer is know as neral or citral B
2

3. • The isomer geranial has strong lemon odor.
• The isomer neral has less lemon odor and
sweeter.
3

4. Physical properties of citral
• Citral is a clear yellow colored liquid with a
lemon –like odor. Less dense(0.9 g/cm-3)
then water and insoluble in water.
• melting point of citral is <-10
• When heated to decomposition it emits
acrid smoke and irritating fumes
4

5. Occurrence
• Citral is present in the oils of several plants
including
Lemon balm (11%) Lemon (2-5%) Lemon iron bark
(26%)
5

6. Lemon verbena (30-35%) Lemon grass (65-85%)
Lemon myrtle (90-98%) 6

7. applications
• It is used in perfumes and flavorings and in the
manufacture of other chemicals.
• Citral also has a significant role in the
production of vitamin A.
• Citral has an effect on some insects. It has a
mild repellent action for some species.
• It also appears to act as a sex pheromone for
the green-veined white butterfly, released by
males to attract mates
• Citral has strong antimicrobial qualities
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8. perfume Insect repellents
pheromones
8

9. Isolation of citral
• Citral is isolated from lemon grass oil which
is obtained from lemon grass by steam
distillation
9

10. Method of steam distillation
• Lemon grass (chopped) is filled in the
distillation flask and fitted tightly ( so the
vapours and oils was not leaked out )
• then the stem is injected in to it so that the
upcoming steam carries away essential oil from
the plant material.
• Then the lemon grass oil as well as the vapours
are passed through the surface of water and it
is then easly separated now .
10

11. 11

12. synthesis methods
12

13. Laboratory synthesis
These two reaction is happen in succession when the two starting
materials are heated together , and the reaction is driven by formation of
conjugated carbonyl group in the product
3methyl-3butenal
3-methyl-2-butenol
13

14. Structure elucidation of citral
• Citral form both mono and bisulfite by addition of
sodium bisulphate to reveal the presences of
conjugated aldehyde group it’s uv spectrum displayed
a band at 238 nm to confirm this.
14

15. • Formation of an oxime of citral indicated
the presences of oxo group in citral
• Citral when heated with potassium hydrogen sulphate afforded
the know aromatic hydrocarbon, p-cymene, which fixed the
position of methyl and isopropyl groups in citral
CHO
Citral (a)
Geranial (trans)
+ NH2OH
CH N OH
Oxim
15

16. • Citral on oxidation with alkaline permanganate,
yielded acetone, oxalic and levulenic acid.
• Citral oxidation with silver oxide afforded an acid geranic
acid, C10H16O2 containing the same number of carbon atoms
suggesting that citral had an aldehyde group.
16
CHO
Citral (a)
Geranial (trans)
i) KMnO4
ii) CrO3
+ +

17. • Citral on reduction with sodium-amalgam citral gave an
alcohol, geraniol, C10H18O.
17

18. Evidents by Mass spectrum
 molecular mass of
citral is 152
It show a peak at
m/Z 29 due to
hemolytic alpha
cleavage
Peak at m/Z 69 due to
beta cleavage
Peak at m/Z 124 due
to heterolytic alpha
cleavage
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19. Evidents by Infrared spectrum
 C=O 1740-1720
 CH2 bending 1475
 C=C 1680-1600
 CH3 bending 1450
& 1375
CH stretch for
alkanes 3000-2850
19

20. Evidents by NmR
• Value of CH2 (A) and CH3 (B) are different
due to different magnetic shielding effect
of the carbonyl double bond in CHO
20

21. References
• Journal of antivirals and antiretrovirals ( synthesis of 3,7-
Dimethyl-2,6-Octadienal Acetlals from citral extracted from
lemon grass , Cymbopogon citrates L
• www.chemical book .com / chemical product property E
N_CB8364074.ht
• Online library .wiley.com/ doi/10.1002/hlca.19760590642/pdf
• www.process-nmr.com/citronella_essential_ oil .htm
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