Experiment 5 - Isolation of Trimyristin Post Lab PDF

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Isolation of Trimyristin from Nutmeg and Preparation of Myristic Acid from Trimyristin by Hydrolysis Post lab report. Grade: 40/40...

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Isolation of Trimyristin from Nutmeg and Preparation of Myristic Acid from Trimyristin by Hydrolysis

Introduction Natural products chemistry is the study of a substance that is produced by a living organism. It helps the understanding of biological processes and identifying compounds. This study is typically very complex in plants because of the many compounds1. When working with organic compounds, such as spices like nutmeg, extraction is used. Extraction is the transferring of compounds from one phase, typically solid or liquid, into a different phase2. Extraction requires another separation step, such as distillation afterwards. In this experiment, we conduct extraction in the first week, and hydrolysis in the second week. When an ester is hydrolyzed, it results in an alcohol and a carboxylic acid3. Trimyristin goes through a specific type of hydrolysis to form myristic acid. Once the hydrolysis is finished, a salt acidifies into myristic acid. Once everything is produced, the melting points are measured, first separately and then in a 50:50 ratio (of trimyristin and myristic acid). The mixed melting point range is essentially to clarify the differences between pure and impure samples. The aim of this experiment is to isolate a single pure compound, trimyristin, from a complex mixture of natural products in its source, nutmeg. It is also to synthesize myristic acid from trimyristin by base promoted hydrolysis. Reaction mechanism:

Side reaction mechanism that occurs during the hydrolysis:

Experimental Section Part A – Isolation of Trimyristin

50 mL Conical Flask

+ 2 g of ground nutmeg + 20 mL of diethyl ether + Swirl and stir vigorously for 15 min

Mixture of Nutmeg and Ether

Pasteur Pipet

Collect Fractions into 25 mL Flask Solid

Purification by Recrystallization

Pure Trimyristin Trimyristin Part B – Hydrolysis of Trimyristin

+ Pack with cotton + 2 mm sand + Fill with 1 cm anhydrous sodium sulfate + Clamp over a pre-weighed 10-mL or 25-mL vacuum flask + Transfer contents from conical flask + Rinse with 0.5 mL ether + Remove solvent by evaporation + Weigh + Save a few mgs for m.p. + 0.5 mL of acetone + Dissolve by heating + Cool to R.T., 0oC + Collect crystals by suction filtration + Weigh + Calculate percentage yield + M.p. of both pure and crude

10 mL Vial

Reflux for 1 Hour

Crude Solid Product

Filter Pipet

Myristic Acid

+ 0.2 g of Trimyristin + 2 mL of ethanol + 2 mL of 10% NaOH + Boiling stones + Micro-reflux set up + Pour product to beaker having 10 mL 10% HCl + Swirl + Collect solid by vacuum filtration + Transfer crude product to test tube having 3 mL petroleum ether + Pass solution through filter pipet (pasteur pipet + cotton + celite) + Pass it with petroleum ether + Collect fractions + Evaporate petroleum ether + Weigh + Calculate percentage yield

Pure Myristic Acid

Mixed Melting Point Concept

+ Weigh equal amounts of trimyristin and myristic acid + Measure of m.p. of the mixture + Notice the m.p. value

Chemicals Used Structure

Formula Molar Mass

Boilin

Meltin

g Point g Point (oC)

(oC)

IUPAC Name

C45H86O6

Trimyristin

C14H28O2

Myristic

723.1

311

56-58

2,3-

6

di(tetradecanoyloxy)propy

g/mol

l tetradecanoate

228.3

326.2

54-55

Tetradecanoic Acid

7

Acid

g/mol

Results

Mass (g) Percent Yield (%) Melting Point (oC)

Trimyristin 0.25 25% 40 – 50

Myristic Acid 0.20 10.5% 50 – 52.4

1:1 Mixture of Both NA NA 55 – 58.3

% yield = (actual yield/theoretical yield) x 100% % yield of Trimyristin = (0.25/ 1) x 100% = 25% % Yield of Myristic Acid: Theoretical moles = 2 g Trimyristin x (1 mol/ 723.16 g) = 0.0028 mol 1 mol of Trimyristin – 0.0028 mol (limiting reagent) 3 mol of Myristic Acid – 0.0084 mol 0.20 g Myristic acid x (1 mol/228.37) = 0.00088 mol Myristic acid % yield of Myristic acid = (0.00088 mol / 0.0084 mol) x 100% = 10.5% Discussion The trimyristin melting point literature value was between 56-58 degrees Celsius, and in the lab, we calculated a range of 40-50 degrees Celsius. The myristic acid melting point literature value

was between 54-55 degrees Celsius, and in the lab, we calculated a range of 50-52.4 degrees Celsius. The melting point ranges could be off due to impurities within the sample, or human error in reading the chart correctly. The percent yield for trimyristin was 25% and the percent yield for myristic acid was 10.5%. The percent yields being less than 50% could be due to an incomplete reaction, or even sample loss. We used the mixed melting point concept to determine the preparation of myristic acid. The mixed melting point range is 55-58.3 degrees Celsius, and the range for trimyristin is 56-58 and the range for myristic acid is 54-55. The mixed melting point range quite literally is the combination of the two compounds. Conclusion The objective of this experiment is to isolate a single pure compound, trimyristin, from a complex mixture of natural products in its source, nutmeg. It is also to synthesize myristic acid from trimyristin by base promoted hydrolysis. I believe that the objectives were not fully accomplished – we did complete all the objectives, but since the percent yield is under 50% and the melting point range suggests that the compound is impure, we were not fully successful. The theoretical background and results we got were connected since we did meet most of the objectives and were able to conduct the experiment. Natural product chemistry can be used in the development of new drugs4.

References (1) Welegirma, Solomon. Experimental Organic Chemistry: Laboratory Manual, 10th Ed.; University of South Florida: Tampa, 2021

(2) Nichols, Lisa. “4.2: Overview of Extraction.” Chemistry LibreTexts, Libretexts, 28 May 2021, https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Organic_Chemistry_Lab_Te chniques_(Nichols)/04%3A_Extraction/4.02%3A_Overview_of_Extraction.

(3) Hunt, Dr Ian R. “Hydrolysis of Esters.” CH20: Hydrolysis of Esters, University of Calgary, https://www.chem.ucalgary.ca/courses/353/Carey5th/Ch20/ch20-3-3-1.html.

(4) UCSD. “Natural Products Chemistry.” Scripps Institution of Oceanography, University of California San Diego, 2021, https://scripps.ucsd.edu/research/topics/natural-productschemistry....