Zach Wright, Chemistry 213
Synthetic #1 FFR
Steam Distillation of Clove Buds
Introduction
Steam Distillation is widely used for separating compounds that are sensitive to temperature that
would otherwise be degraded at high temperatures.1 The essential oil found in plants can be co-distilled
with water resulting in a non-degraded product. The essential oils derived from many plants have been
used for thousands of years by humans to treat for a variety of afflictions.2 During this experiment the
essential oil from cloves was extricated from clove buds using steam distillation and the resulting oil
was tested for antimicrobial activity.
Clove oil extracted from clove buds contains eugenol, caryophyllene, and eugenyl acetate.3 The
main component eugenol exhibits some very unique properties including the ability to relieve pain,
promote healing. In addition to topical pain relief applications eugenol exhibits antimicrobial
properties.4 Eugenyl acetate can be used as a flavoring agent as well as caryophyllene.5
Natural products are important for understanding exactly why certain compounds exhibit
extraordinary functions like the essential oils found in cloves. The structure of these naturally occurring
compounds can be used as models for other synthetically derived pharmaceutical drugs as well as
precursors for other drugs. The understanding of how components interact with the outside world can be
accelerated through the study of naturally occurring products.
In order to separate the three main temperature sensitive chemical components from the clove
buds steam distillation was utilized. Steam distillation takes advantage of the unique properties of water
and partial pressure. Water boils at about 100C at atmospheric pressure which is low enough as to not
degrade the compounds of the essential oil. The essential oil is immiscible with water and will therefore
form a partial pressure that is independent of all other components in the system. The additional pressure
from the immiscible clove oil allows water to reach atmospheric pressure faster while being heated and
will therefore boil at a temperature slightly below 100C. As water evaporates it van act as a medium of
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transportation for the volatile vapors of the components that have not fully reached the pressure needed
to completely vaporize. Sweeping of the volatile compounds with water as a medium is a slow process
and therefore the solution must be carried out over a long period of time. By using stream distillation
one can isolated the essential oils from cloves though degradation which allows for a simple extraction
for further analysis and identification.
The purpose of this experiment was to isolate the essential oils contained in clove buds and to
analyze their antimicrobial activity. Isolation was performed by steam distillation and the product
composition was analyzed using GC and GC-MS.
Experimental
Cloves (4 g) were ground to a fine powder and suspended in water (50mL). The immiscible solution was
distilled for 2 hours at 100C. The collection flask was kept on ice. The aqueous layer was extracted
using dichloromethane (3x15mL). The organic layer was dried over anhydrous sodium sulfate. The
solvent was evaporated resulting in a small volume of yellow liquid. (0.366, 6%) GC (phenyl methyl
silicone, 40°C to 250°C at 10°C per min) RT 11.62 min, 12.44 min, 13.56 min; GC-MS (phenyl methyl
silicone, 40°C to 250°C at 10°C per min) RT 13.43 min, m/z 164.02, 14.06 min, m/z 204.13, 14.85 min,
m/z 206.1.
Results Discussion and Conclusion
The essential oil from cloves was isolated from clove buds using steam distillation to prevent
degradation of the oil. After the isolation the cloves were analyzed using a bioassay. Although the
percent recovery for this experiment was only 6%, which is not unexpected and correlated well to the
reported 5% found in literature, the oil still showed antimicrobial properties.
After preparing a culture from the [name of bacteria] two disks were sterilized using acetone.
One of the disks was dipped into a solution of the clove oil in acetone and the other was left as it was.
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The disk was left for an incubation period of 120 hours. From figure one there is a clear retardation of
the growth of the bacteria that surrounds the disk that was dipped in the oil from the clove isolation. In
contrast bacterial growth can be seen surrounding the white control disks in the bottom left as well as
through the rest of the plate. The retardation of bacterial growth surrounding the clove oil disk clearly
illustrates the antimicrobial properties of the oil and confirms the numerous reports found in literature.
Figure 1
The antimicrobial properties comes from the main component of the oil eugenol. In order to
confirm that the oil extracted from the cloves contained eugenol and the two other main components
caryophyllene, and eugenyl acetate GC and GC-MS were run on the sample. From the GC(add figure
number) and GC-MS(add figure numbers) the clove oil was found to be composed of eugenol 86%,
caryophyllene 7% and eugenyl acetate 7%. Although the GC-MS retention times did not match up
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perfectly to the GC retention times I was able to determine what retention times matched up, based on
the order that the compounds should move through the column, with the lightest eugenol having the
lowest retention time and eugenyl acetate having the highest retention time. Also the time between the
sample retention times was about the same. Table 1 summarizes the % composition of each component
determined by GC and GC-MS.
Component
RT
Area
m/z
% Composition
Eugenol
11.62
1.072
164
86
β Caryophyllene
12.44
0.092
204
7
Eugenyl Acetate
13.56
0.086
206
7
Table 1
The essential oil from cloves was isolated from clove buds using steam distillation. The mixture
of compounds in the oil was analyzed using GC and GC-MS. The bioassay supported the claims that the
main component of clove oil, eugenol, has antimicrobial properties. Add how these results were
confirmed.
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