Synthesis and Characterization of Myristic Acid (Soap) from Nutmeg
Wooshik Kim
Introduction
Vegetable oils and animal fats are attracting many scientists’ attention because several
studies suggested that they can be used to solve the energy source problems since the energy
sources of transportation and other mechanical objects are depleting. The unique form of
vegetable oils or animal fat called Biodiesel is used as an alternative fuel which can grant
renewable energy.1
Vegetable oils and animals fats can also be used to more general area that people are
more familiar of. They can be used to make soaps. In everyday life, soap is used to clean both
water-soluble compounds and non-polar compounds which are bound to hands, face, and other
objects. The unique characteristics that soap contains help to succeed in this area. The
characteristics contain both hydrophobic and hydrophilic properties. When cleaning, soap creates
a sphere called micelles which have hydrophilic ends pointing to the outside and hydrophilic end
pointing to the interior of the sphere. Since soap has these two properties, when the compounds
make contact with the soap, the properties allow the compounds to mix with polar and nonpolar
parts of the micelle to form emulsions. Therefore, the emulsion can be washed away with stream
of water.
Soap is usually made by mixing large triglycerides which are esters derived from
glycerides and fatty acid with strong base. Under the mechanism of saponification, the strong
base helps the triglycerides to cleave itself into three molecules by attacking the double bond
with carbon and oxygen with its lone pair at OH-. Then, the double bond is reduced to a single
bond with oxygen containing a lone pair. The lone pair tries to make double bond again by
cleaving the bond with ester oxygen. The two other ester functional groups react under this path
to cleave themselves. After the completion, three salt of carboxylic acids and alcohols are
collected. There are several techniques to improve the synthesis of soap which include enzyme
catalyzed hydrolysis, high pressure hydrolysis of fats, and hydrolysis of oils using hydrodynamic
caviation.2
Although the synthesis of soap in this experiment was based on chemical reaction of
hydrolysis to make fatty acid and alcohol, it was studied that instead of chemical hydrolysis,
enzyme catalyzed hydrolysis such as lipase yields better results and more convenient method
because synthesis can occur at atmospheric pressure and approximately in room temperature.3
In this experiment, synthesis of myristic acid was carried out by first making trimyristin
from nutmeg. By refluxing nutmeg and vacuum filtering the product, trimyristin was collected.
The collected trimyristin was recrystallized using ethanol to purify the product. Also, trimyristin
was analyzed with IR spectrum and melting point equipment to confirm the product and
recognize the purity of the compound. Next, trimyristin was refluxed with strong base to yield
sodium myristate. IR spectrum was used to analyze the compound and percent yield was
calculated. Then, myristic acid was made by acidifying the solution with strong acid to add
hydrogen at the lone pair of the oxygen. Then, it was vacuum filtered to collect the final product.
IR spectrum and melting point equipment was used to determine the purity and characteristics of
the compound. The percent yield calculation was used to figure out the successfulness of the
experiment. Along with 60MHz H-NMR for myristic acid, to get more descriptive results,
400MHz H-NMR was also used for myristic acid.
Experimental
1. Trimyristin. Ground nutmeg (20g), diethyl ether (50mL), and magnetic stir bar was inserted
into a 100mL round bottom flask. Heating mantle without the sand was place on the stir plate
with Varistat of 40. Then, reflux condenser with water path was attached to the flask. Water was
turned on to flow from bottom to top of the water condenser. The mixture was refluxed for 30
minutes. The refluxed solution was transferred to large beaker after it was cooled. Vacuum
filtration was performed using Buchner funnel to collect the ether layer from the residual nutmeg
compounds. Additional ether (10mL) was filtered through the nutmeg to collect remaining
product. The collected ether layer was allowed to evaporate using stream of N2 gas. Then, the
product was dissolved in warm ethanol (95%) and recrystallized to purify the compound. The
slush compound from the recrystallization was again vacuum filtered to collect the solids. The
solids were washed with cold ethanol to remove the impurities. Mass (2.352g) and melting point
range (51-53 degree Celsius) (lit: 56-57 degree Celsius) were measured. Also, IR spectrum was
used to confirm the characteristics of trimyristin.
IR Data: Run with solid trimyristin on the solid IR spectrometer
Observed
Significant Signals
Bond Stretch
2913.1 cm-1
1730 cm-1
1171 cm-1
Alkane C-H
Ester C=O
C-O
2. Sodium Myristate. Ethanol (20mL, 95%), Sodium Hydroxide pellets (0.20g) were added into
a 100mL round bottom flask. The solution was stirred until the pellets were dissolved. Collected
trimyristin (1.0g) was added into the round bottom flask. The water condensing refluxer was also
attached to the round bottom flask. The solution was refluxed for 20 minutes. The solution was
cooled then; distilled water (20mL) and saturated Nacl (20mL) were added. The solution was
vacuum filtered to collect the product and additional cold water (25mL) was used to wash
sodium myristate. The mass (5.561g) and percent yields (536%) were calculated. Also, IR
spectrometer was used to confirm the product.
IR Data: Ran with solid sodium myristate on IR spectrometer.
Observed
2919.5 cm-1
1745cm-1
3403.1
Significant Signals
Bond Stretch
Alkane C-H
C=O
O-H water
3. Myristic Acid. The collected sodium myristate (0.5g) was dissolved into distilled water
(40mL). The dissolved solution was distributed into three test tubes (5mL each). The first test
tube contained corn oil (3drops). The second test tube contained aqueous FeCl3 (1%, 10drops)
and third test tube contained aqueous CaCl2 (1%, 10drops). Each test tube was shaken vigorously
and emulsions, brown precipitate (iron III myristate) and white precipitate (calcium myristate)
were observed respectively. The remaining solution was cooled in an ice bath. Then, the solution
was acidified by adding concentrated HCl. pH paper was used to confirm it was below pH of 4.
The white precipitate was observed and vacuum filtration was performed to collect these
compounds. Chilled water (10mL) was used to wash the collected compounds. Mass (0.22g) of
myristic acid was measured and percent yield (74%) was calculated. IR spectrometer was used to
confirm the characteristics of myristic acid. Also, 60MHz and 400MHz H-NMR were performed.
The melting point range was determined to be 46 to 48 degree Celsius (lit: 52 to 54 degree
Celsius)
IR Data: Ran with solid myristic acid on IR spectrometer
Observed
2914 cm-1
1692 cm-1
3372.3 cm-1
Significant Signals
Bond Stretch
Alkane C-H
Ester C=O
O-H
60 MHz H-NMR Data: Ran with solid myristic acid dissolved in D-Chloroform on H-NMR
Observed
11.476ppm
2.348ppm
1.259ppm
0.951ppm
Significant Signals
Splitting, type of hydrogen
S, RCOO-H
T,R-CH2-R
M, R-CH2-R
T,R-CH3
400Mhz H-NMR Data: Ran with solid myristic acid dissolved in D-Chloroform on H-NMR
Observed
11.936ppm
2.325 ppm
1.6104 ppm
1.2575 ppm
0.8622 ppm
Significant Signals
Splitting, type of hydrogen
S, RCOO-H
T,R-CH2-R
M, R-CH2-R
M, R-CH2-R
T,R-CH3
Results and Discussion
For the synthesis of trimyristin, because the molecular formula and the molecular weight
was not given the percent yield could not be calculated. The mass collected was 2.352 grams
which was in the range of 1.5 to 2.5 grams that hand out predicted. Trimyristin is a large
molecule which contains triesters that are connected with glycerides to from triglycerides.
Trimyristin showed three distinct peaks on the IR spectrum. The three significant peaks were
2913.1, 1730, and 1171 cm-1. The results were consistent with the prediction because 2913.1
cm-1 signal represented the long alkane carbons which were bonded to the hydrogen. 1730 cm-1
represented the peaks which ester carbons that are double bonded to the oxygen. Lastly, 1171
cm-1 represented the single ester bond with carbon and oxygen. The theoretical melting point
range for trimyristin is 56 to 57 degree Celsius and the actual melting point range was 51 to 53
degrees Celsius. According to the IR spectrum and the melting point range, it could safely be
concluded that the synthesis of trimyristin was successful.
For the synthesis of sodium myristate, the significance of adding saturated NaCl after the
addition of strong base was to provide the sodium cation to stabilize the lone pair (anion) of
oxygen. The percent yield was 536% which was a very big discrepancy for collected product.
The possible source of error is that even though, sodium myristate was given time to make it dry,
there could have been solution remaining in the product. Also, the two different scales were used
to measure the weight of the watch glass and the mass of the watch glass plus the collected
sodium myristate. The IR spectrum of sodium myristate showed three significant signals which
were 3403.1, 2919.5 cm-1 and 1745 cm-1. The peak around 3403.1 cm-1 represented the bond
between oxygen and hydrogen which are present in water. This supported the theory that water
was still present in the collected product and the reason why the percent yield for sodium
myristate was so high. The signals 2919.5 cm-1 and 1745 cm-1 represented the same alkane group
and ester double bond with carbon and oxygen group that trimyristin had. Unlike trimyristin, the
predicted absorption frequency at ester single bond of carbon was not present on this graph
because sodium myristate no longer has ester group. These results were consistent with the
characteristics of sodium myristate. It could be safely concluded that the experiment was
successful.
To test if the collected sodium myristate showed properties of soap, corn oil, FeCl3, and
CaCl2 were used. Since emulsions, iron myristate and calcium myristate were formed
respectively, it could be concluded that the synthesis of sodium myristate was successful. The
significance of adding strong acid such as Hydrochloric acid into the dissolved sodium myristate
was to add hydrogen to the oxygen which has a lone pair that is stabilized with sodium cation.
While hydrogen is bound to the oxygen to make carboxylic acid, the sodium cation is attached to
the chlorine anion to form salt. pH paper was used to confirm that the acidity of the solution was
below 4.
The melting point of myristic acid showed that although the actual melting point was
lower than the theoretical values, it was similar to the theoretical value and the collected myristic
acid had some amount of imprities which depressed the melting point range. The IR spectrum
showed three different signals which were 3372, 2914, and 1692 cm-1. The peak 3372 cm-1
represented the oxygen and hydrogen bond group which is unique in carboxylic group. Since
carboxylic functional group was present in the IR spectrum, it proved that the acidification of the
sodium myrisistate successfully disconnected the sodium cation bond and added hydrogen to the
remaining oxygen. 2914 cm-1 (C-H) and 1692 cm-1 (C=O) represented the same functional
groups that trimyristin and sodium myristate had.
Also, 60MHz H-NMR was used to analyze myristic acid. Myristic acid has a long alkane
chain group and a carboxylic acid group. It was predicted that 4 significant peaks would be
present. In fact, the prediction was right and four peaks showed on the H-NMR spectrum. The 4
significant peaks were at 11.476ppm, 2.348ppm, 1.259ppm, and 0.951ppm. The singlet peak at
11.476ppm represented the hydrogen A which was attached to the carboxylic group. The integral
number was 0.57 which is very close to 1. In fact, there was only one hydrogen which was
attached to that group. The triplet at 2.348ppm had integral number of 2 which represented the
two hydrogens which were attached to the carbon B. The spectrum was also consistent with the
prediction because the carbon next to the carbon containing hydrogen B had two other hydrogen
so n+1 yielded triplet. The giant peak at 1.259ppm represented the hydrogen which were
contained in long carbon chain. Because all the spectrums were close together, it resulted as one
big singlet peak. Also, the theoretical integral number was 22 and the actual integral number was
24. The triplet peak at 0.951ppm showed the hydrogen D. The theoretical integral number was 3
and the actual number was 3.15. This also confirmed that the product was successfully made
because hydrogen D contained 3 hydrogens.
Myristic acid was further analyzed with 400MHz H-NMR to confirm that the purity of
the product was successful. The significant peaks were 11.936, 2.3258, 1.6104, 1.2575,
0.862ppm. Unlike 60MHz H-NMR, it showed five different peaks in the spectrum. The integral
number of hydrogen bonded to the carboxylic acid was 0.752 (11.936ppm) which was closer to 1
than the result from the 60MHz H-NMR. The splitting pattern of this peak was singlet which was
consistent with the prediction. The peak at 2.3258ppm showed triplet which signified hydrogen
B. The chemical shift of this hydrogen was higher number than other hydrogen which were
attached to alkane carbons because hydrogen B was close to oxygen which tends to increase the
hydrogen near it. The peaks at 1.6104 and 1.2575ppm were multiplets which represented the
hydrogen Cs which were attached to the long alkane chain. Because 400Mhz H-NMR is more
accurate device, it was able to recognize the small chemical shift difference and to separate the
peaks. Also, the addition of integral number of hydrogen Cs was 22.6 which was very close to
the theoretical value of 22. The peak at 0.862ppm showed triplet which represented hydrogen D
which was attached to the last carbon on the long alkane chain. The integral number for this
hydrogen was 2.972 (predicted value of 3).
The goal of this experiment was to synthesize myristic acid from nutmeg by collecting
trimyristin from nutmeg, saponifying trimyristin to collect sodium myristate and finally
synthesizing myristic acid from sodium myristate with strong acid. Melting point, IR spectrum,
H-NMR and various tests results were obtained to confirm the products for each synthesis. The
melting point, IR spectrum and H-NMR showed that each product had the expected
characteristics of the theoretical yield. Therefore, the results obtained supported the predicted
results and it could be concluded that the synthesis of soap from nutmeg was successful.
References
1
Gopinath, A., Sukumar Puhan, and G. Nagarajan. "Theoretical Modeling of Iodine Value and
Saponificationnext Term Value of Biodiesel Fuels from Their Fatty Acid Composition."
Renewable Energy 7th ser. 34 (2009): 1806-811
2
Bhatkhande, B. S., and S. D. Samant. "Ultrasound Assisted PTC Catalyzed Saponification of
Vegetable Oils Using Aqueous Alkali." Elsevier 5.1 (1998): 7-12.
3
M. Virto, I. Agud, S. Montero, A. Blanw, R. Solozabal, J. Lascary, M. Llama, J. Serra, L.
Landeta and M. deRenobales. Enzyme Microb. Technol. 16 (1994), p. 61.
4
https://cms.psu.edu/section/default.asp?id=201011FAUP___RCHEM_213_102 “Soap From
Nutmeg”