Introduction
This experiment is designed to isolate myristic acid from trimyristin through a saponification process. Trimyristin is a lipid found in blood and stored in fat cells; when one eats calories, it does not need to be used immediately. Later, hormones release the product to supply energy between meals. This product is composed of three fatty acids esterified to a glycerol molecule. Myristic acid is one of the fatty acids in the product trimyristin (Padro et al., 2021).
The process of saponification involves the hydrolysis of esters using a solid base. Sodium hydroxide, NaOH, is among the most commonly used compounds for hydrolyzing acids, producing a safe alcohol and a carboxylate salt. For this experiment, trimyristin has an ester bond, which will be hydrolyzed using NaOH to break it into triglycerides composed of myristic acid and glycerol.
The reaction to break down this lipid is carried out under reflux conditions to ensure the reaction mixture remains at a constant pressure. It is worth noting that all the components used in the experiment have a volatile nature and could be lost by slight changes in temperature. After refluxing, the reaction mixture is poured into the beaker containing cold water and saturated NaCl. This step operates on the principle that sodium myristate is not soluble in water but is miscible with ethanol, making it hard to separate from the residues of the reaction mixture (Franco et al., 2021).
Adding NaCl allows myristic acid to precipitate from the rest of the aqueous solution, allowing easier separation from the mixture. Myristic acid is then collected by vacuum filtration and washed with cold water to remove all impurities that may have dissolved upon the addition of NaCl. The solid product is then crushed with a spatula while filtering to remove most of the water, and allowed to dry. Only a thoroughly dried product is weighed.
Procedure
For the experiment, 0.45 g of trimyristin was placed in a 25 ml round-bottomed flask. One pellet of sodium hydroxide (NaOH) was added to this flask. 10 ml of absolute ethanol was poured into the flask containing a mixture of trimyristin and NaOH. The flask was then fitted with a stirring bar and a condenser.
After this preparation, the reflux of the mix was conducted for about 14 minutes. The refluxing process involved heating the mixture to the boiling point and continuously condensing it. The condensed vapor was returned to the flask. After the reflux, the recreated mixture was poured into a clean beaker filled with 10 ml of cold water and 20 ml of saturated aqueous NaCl (sodium chloride) solution.
The whole combination was stirred using a glass rod to break the solid into a clear white product into small pieces. This product was tested and found to be sodium myristate. The resultant solid was collected through vacuum filtration. The filtered product was then rinsed with cold water to remove all impurities. The product was then crushed with a spatula during filtration to remove most of the water from the sample. The isolated sodium myristate was then allowed to dry thoroughly. The mass of the dry solid was determined and recorded for further analysis.
Results
Table 1 – Trial Results
The average mass of sodium myristate is 0.731g.
Discussion
The percentage yield of myristic acid from trimyristin is given by (0.731/0.45) x 100% = 162.44%. Based on these calculation results, the product obtained is more significant than 100%, suggesting some errors in the experiment (Pirzadi & Meshkani, 2022). One potential source of errors is incomplete drying of the product or loss of product during filtration. To some extent, an inadequate wash of impurities contributes to this ambiguous yield percentage.
The purpose of refluxing in this experiment is to ensure that saponification of trimyristin occurs efficiently. Reflux is critical in the investigation as it allows continuous heating at the mixture’s boiling point. As a result, the reaction rate is optimized to yield maximum output (Pirzadi & Meshkani, 2022). Moreover, the step prevents the volatile reactants and products from reacting and ensures that they produce more of the desired product, rather than getting lost in the process.
Absolute ethanol is used in the reaction because it has anhydrous characteristics. The ability to contain water allows complete saponification. Due to the sensitive nature of this reaction, water makes it easy for the base NaOH to hydrolyze the trimyristin, which leads to side reactions and reduced yields (Subroto & Yarlina, 2020). Absolute ethanol helps ensure that the reaction proceeds predominantly through saponification, which results in the extraction of a purer product.
Adding saturated aqueous NaCl after the saponification reaction separates the mixture from the reaction mixture. Ideally, sodium myristate is not soluble in water but can dissolve in ethanol. A saturated NaCl solution precipitates sodium myristate and allows for more accessible collection through vacuum filtration (Subroto & Yarlina, 2020). On the other hand, other components of the reaction mixture remain in an aqueous state and do not interfere with the collected solid.
Rinsing the collected product with cold water is vital in removing all impurities that might have bypassed the filtration stage. Cold water also prevents the dissolution of the sodium myristate and the other contaminants present in the mixture. Moreover, cold water prevents the loss of the collected product by isolating it and ensuring a higher purity. This step provides an accurate yield of the myristic acid from the entire experiment.
Allowing sodium myristate to dry thoroughly before calculating its mass is a step used to increase accuracy. Upon complete drying, the amount of solid collected is not overestimated. Therefore, the group measured represents an accurate yield obtained from the experiment. Active crushing of the solid product with a spatula while filtering is recommended to remove excess water (Pirzadi & Meshkani, 2022). The pressure exerted during the crushing drives the excess water out of the particles and improves the efficiency of the drying process. As a result, the product dries faster and more accurately when the weight is determined.
Conclusion
Overall, the saponification process and role of NaOH are represented by the equation: Trimyristin + 3 NaOH → Glycerol + 3 Sodium Myristate. This reaction involves the hydrolysis of the triglyceride trimyristin in the presence of a strong base. NaOH acts as a catalyst in the reaction, hastening the breakdown of ester bonds.
The reaction results are the formation of glycerol (alcohol) and the product of interest, three molecules of sodium myristate. The sodium salts of myristic acid are insoluble in ethanol, meaning they precipitate out of the reaction mixture. As a result, it can be isolated from the reaction mixture as a solid product and weighed. The experiment is successful and shows that saponification of trimyristin yields myristic acid.
References
Franco, A., Salvia, R., Scieuzo, C., Schmitt, E., Russo, A., & Falabella, P. (2021). Lipids from insects in cosmetics and for personal care products. Insects, 13(1), 41.
Padro, T., Muñoz-García, N., & Badimon, L. (2021). The role of triglycerides in the origin and progression of atherosclerosis. Clínica e Investigación en Arteriosclerosis, 33, 20-28.
Pirzadi, Z., & Meshkani, F. (2022). From glycerol production to its value-added uses: A critical review. Fuel, 329, 125044.
Subroto, S. P., & Yarlina, A. D. (2020). The extraction, purification and the recent applications of coconut oil in food products–A review. International Journal on Emerging Technologies, 11(5), 234-240.