Benjamin Sepe, Chem 213 Synthetic #4 FFR

Making Soap from Nutmeg

Introduction

Soap is an essential compound in today’s society. Dating back thousands of

years to its crude synthesis from animal fats mixed with basic salts; the multifaceted

cleanser has since exploded into seemingly every trade.1 Its functions as a detergent

range from the industrial application of alkyl polyethoxylates in paper, textile, and

spermicide production to the world of medicine, where they are used in vaccines

and disease treatment.2, 3 The average person, however, most likely interacts with

soap as a personal hygiene tool or in the act of cleansing fabrics.

Soap is known as an “amphipathic” molecule, meaning that it consists of two

regions that differ in polarity.4 This difference in polarity is a result of the molecule’s

long hydrophobic alkane “tail” and ionic “head” that is, in turn, hydrophilic.4 These

differing polarities are the root of soaps unique ability to removing grease and oils

from solution. As depicted in Figure 1, soap molecules readily form what are

referred to as “micelles” in aqueous solution.5 These micelles often spawn around oil

and grease due to the hydrophobic tail of a soap molecule readily dissolving in

hydrophobic grease.4 The hydrophilic head remains at the surface of the micelle,

however, at it is attracted to the polarity of surrounding water. 4 Thus, when the

soapy solution is rinsed away, the micelle will wash away too, taking the grease with

it and leaving the fabric or dish unsoiled.

Figure 1. A Soap Micelle.5

Soap molecules are synthesized by a mechanism called saponification. The

mechanism of saponification in basic solution is characterized by the SN2 attack of a

hydroxide group on an ester’s carbonyl group, resulting in an electron pushing

mechanism that cleaves the ester bond. This yields a carboxylic acid that is quickly

deprotonated by the removed alkoxide, yielding an enolate and an alcohol. The

negative enolate ion is quenched, in most cases, by the positive sodium ion of

sodium hydroxide. This general mechanism is depicted in Scheme 1.6

Scheme 1. Saponification: General Mechanism6

In naturally occurring fatty oils, the mentioned esters are usually found in

groups of three, referred to as triglycerides. The triglyceride that is used in this lab

is trimyristin. The synthesis calls for three equivalents of sodium hydroxide, and

each molecule of trimyristin yields three molecules of the soap sodium myristate

and one equivalent of glycerol. The complete electron pushing mechanism for the

synthesis of sodium myristate from trimyristin is depicted below in Scheme 2.

Scheme 2. Electron Pushing Diagram for Synthesisof Sodium Myristate from Trimyristin

In this lab, the fatty oil trimyristin is extracted from ground nutmeg.

Saponification of trimyristin yields sodium myristate and glycerol. The extraction of

a fatty oil and successive saponification has been repeated time after time for the

last 5 millennia as a way of producing some of the most versatile compounds known

to man. In this lab, trimyristin and the soap sodium myristate may be analyzed by

melting point and IR analysis to provide evidence that this synthesis was after all

those years, once again, successful.

Experimental

Trimyristin. Nutmeg (5.008 g) and diethyl ether (12.5 mL) were added to a 100 mL

flask, refluxed for 30 minutes, then cooled to room temperature. Vacuum filtration

removed residual Nutmeg from the product. Drying provided crude trimyristin as a

yellow solid. Crude trimyristin was recrystallized in 95% ethanol at 50 OC. Vacuum

filtration afforded pure trimyristin as a white powder (0.333 g, 6.65%) mp 52 – 54

OC; IR (ATR) νmax (cm-1) 2954.8, 2915.4, 2849.2, 1732.3, 1175.7.

Sodium Myristate. 95% Ethanol (4 mL) and NaOH pellets (0.0425 g) were added to

a 50 mL flask and stirred until homogeneous. The solution was combined with

trimyristin (0.2013 g) and refluxed for 15 minutes. To the product, distilled water (4

mL) and saturated NaCl solution (8 mL) were added. Vacuum filtration afforded

Sodium Myristate as a white powder (0.2933 g, 153.8 %); IR (ATR) νmax (cm-1)

2919.7, 2847.2, 1556.6, 1461.4, 1445.5, 1421.3, 722.1, 697.4.

Discussion and Conclusions

The extraction of trimyristin from ground nutmeg utilized reflux in diethyl

ether. The product of this reflux is depicted in Figure 2, below. The result of this

reflux was a separated ether layer that contained trimyristin. After vacuum filtering

out the residual nutmeg and extracting any remaining trimyristin with additional

ether, the product was a thick yellow liquid, depicted in Figure 3.

Figure 2. Reflux Result Figure 3. Crude Trimyristin (Wet)

The crude trimyristin solution was given time to dry as diethyl ether

evaporated and afforded a solid crude trimyristin, depicted on the next page in

Figure 4. In order to purify the crude trimyristin, it was necessary to recrystallize

the solid in 95% ethanol, however due to the relatively low melting point of

trimyristin (lit. 56- 57 0C) extra precaution was taken to be sure ethanol did not

exceed this temperature. After recrystallization, trimyristin was evaluated for purity

by means of Thin Layer Chromatography. The Rf value (lit. 0.5) was matched

identically by the product. The TLC plate, run in an iodine chamber is seen below in

Figure 5.

Figure 4. Crude Trimyristin Solid Figure 5. TLC Analysis Pure

IR analysis of the recrystallized trimyristin provided evidence that the

product had formed according to plan. In the IR spectrum, provided as

supplementary Figure 6, a strong group of peaks in indicated around 2914 cm-1.

These peaks represent the numerous C-H bonds in the long hydrophobic alkane

chains. Additionally, a large singular peak at 1732.3 cm-1 was indicative of the ester

C=O groups. The esters were again represented as a large peak at 1175 cm-1,

signifying the C-O bonds.

Melting point determination also provided insight into the analysis of this

compound. The observed melting point range of 52 – 54 0C was very close to the

literature value of 56-57 0C, representative of a highly pure substance. The percent

recovery from nutmeg, furthermore, was calculated to be 6.65%.

Saponification of the trimyristin compound was carried out by refluxing the

fatty triglyceride with NaOH pellets in 95% ethanol. After workup, the product

resembled a chalky white powder, depicted below as Figure 7.

Figure 7. Sodium Myristate

Melting point analysis provided evidence as to successful soap salt formation,

as the product reached capacity of the Mel-Temp machine without successfully

turning into a liquid. This behavior is characteristic of these salt soaps. Additionally,

IR analysis of the compound, supplementary Figure 8, provided evidence of

successful saponification. The peaks at 2919 cm-1, similarly to trimyristin, were

representative of the C-H bonds in the long saturated alkane chain. Additionally, the

peaks at 1556.6 cm-1 were indicative of the ester bond formed by the salt soap.

Finally, it is important to note that the small alcohol bump at around 3200 cm-1 was

generated by the small amount of product that formed a carboxylic acid in solution.

The product was in larger than expected yield at 153.8%. One possible

reason for this anomaly could be differences in the scales in our laboratory. With

any two scales differing by as much as 30 milligrams, it is more likely than not that

taking an initial measurement at a scale that under-measured my reagent and taking

a final measurement on a scale that over-measured my product. In the future, more

attention should be paid to the specific scale being used. This scale should be kept

constant throughout the experiment to keep at least relative consistency.

The final analysis that was conducted on the synthesized sodium myristate

was a set of tests including sodium myristate solution, vegetable oil, and 1% FeCl3. A

solution of 0.01 g sodium myristate: 1 mL of water was made in excess. To two

reaction tubes, 5 mL of the solution was added. In Tube A, vegetable oil was added.

The effect was dissolution of additional sodium myristate, indicative of the way that

you would expect soap to dissolve oil. In Tube B, %1 FeCl3 was added. The result

was a precipitate forming, likely a salt (NaCl), indicative of the inability of this

compound to dissolve in the soap water. The results are summarized in Figure 9.

TUBE A: Sodium Myristate + Veg. Oil TUBE B: Sodium Myristate + FeCl3

Veg. Oil was dissolved Precipitate formed, likely NaCl

Figure 9. Results of Chemical Analysis

Given the results of this experiment, it is with reasonable confidence that the

appropriate compound, sodium myristate, was isolated. Using saponification, it was

proven possible to take extracted oils and create a soap product. It is important to

take away from this lab the significance of detergents in everyday life. Their

applications are numerous, and processes much like those in this lab are happening

every day to make our world a better, and cleaner, place.

References

1. De Mattos, M.C.S.; Nicoderm, D.E.; Soap from Nutmeg: An Integrated Introductory Organic Chemistry Laboratory Experiment; J. Chem. Ed. [Online] 2002, 79, 94-95, http://pubs.acs.org/doi/pdf/10.1021/ed079p94 (accessed Dec. 7, 2012)

2. Sonnenschein, C.; Soto, A.M.; An updated review of environmental estrogen and androgen mimics and antagonists. The Journal of Steroid Biochemistry and Molecular Biology. [Online] 1998, 65, 143-150, http://www.sciencedirect.com/science/article/pii/S0960076098000272(accessed Dec. 7, 2012)

3. Bayliss, Milward; Effect of the Chemical Constitution of Soaps upon their Germicidal Properties; J. Bacteriol. [Online] 1936, 31(5), 489-504, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC543736/?page=1 (accessed Dec. 7, 2012)

4. Seddon, A.M; Curnow, P; Booth P.J.; Membrane proteins, lipids and detergents: not just a soap opera; Biochimica et Biophysica Acta Biomembranes [Online] 2004, 1666, 105-117, http://www.sciencedirect.com/science/article/pii/S0005273604001610 (accessed Dec. 7, 2012)

5. Furukawa, J.; Comparison of block-copolymer with soap in micelle formation; Colloid Polym. Sci. [Online] 1993, 271, 852-859, http://download.springer.com/static/pdf/705/art%253A10.1007%252FBF00652767.pdf?auth66=1355108716_b42c376771551c1aeb1700a2e61b42c9&ext=.pdf (accessed Dec. 7, 2012)

6. Estrela, C.; Estrela, C; Barbin, E.L.; Spano, J.C.; Machesan, M.A.; Pecora, J.D.; Mechanism of Action of Sodium Hypochlorite, Braz. Dent. J. [Online] 2002, 13(2), 113-117. http://www.scielo.br/pdf/bdj/v13n2/v13n2a07.pdf (accessed Dec. 7, 2012)