Experiment 5 Report: Liquid CO2 Extraction of D-Limonene from Orange Rind PDF

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Download Experiment 5 Report: Liquid CO2 Extraction of D-Limonene from Orange Rind PDF

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Lexi Finke TA Steve Jackson Experiment 5: Liquid CO2 Extraction of D-Limonene from Orange Rind Introduction In this experiment liquid CO2 was used to extract an essential oil, called D-Limonene, from orange rinds. The CO2 is used as a greener alternative to tradition techniques, such as using pressing or water distillation. It is also safer as it nonflammable, nontoxic, easily available and does not harm the environment.1 When it is used as a solvent, the CO2 is captured by the environment and therefore has a net environmental impact of zero.1 The reason that CO2 is used due to its properties and that it is a supercritical fluid. Meaning that it converts into a liquid when it is placed under extreme pressure. The solid CO2, in the form of dry ice, is placed into tube with the orange rinds. This tube is sealed with a centrifuge cap and placed into a plastic cylinder with hot water. The solid CO2 is melted and the liquid CO2 flows through the orange rind and extracts the limonene, all while evaporating into a gaseous state and leaving through a cap. The limonene and many essential oils that are extracted are classified as terpenes or terpenoids. Terpenoids are an organic compound that consist of many isoprene units that are joined from head-to-tail.1 Terpenoids are divided based off the number of carbon units, or isoprene units it possesses. There are monoterpenes (two isoprene units), sesquiterpenes (three isoprene units), diterpenes (four isoprene units), and triterpenes (six isoprene units).1 The limonene that is extracted from the orange rinds is a monoterpene.1 D-Limonene is an essential oil found in orange rinds and has the molecular formula of

C10 H 16 .1 It is a very versatile oil and can be used in many food items, such as soft

drinks, baked goods and ice cream.2 It can also work as a solvent to dissolve cholesterolcontaining gallstones.2 For this reason, it has been used for medicinal purposes for heartburn relief and acid reflux.2 In addition, it can also be used as a way to prevent/work against certain types of cancer (colon and skin cancer).2 A chiral center is a carbon that has four different groups attached to it. Whether the rotates plane polarized right or left, is dependent on the orientation of the four different groups attached to the chiral carbon.1 The polarimetry measures how/to what degree the D-Limonene will interact with plane polarized light and will tell which way it is polarized (left or right).1 If a substance does not have a chiral center it will not interact, or rotate, in the light.1 By using polarimetry, the optical purity of the D-limonene will also be able to be determined. The optical purity can be determined by dividing the determined/observed angle of rotation and dividing it by +115.5 which is the angle rotation for pure limonene. This can then be multiplied by one hundred, this gives the purity, which is also called the enantiomeric excess. Refraction happens when a light wave passes through, on an angle other than normal, and goes from one medium into another. Such as light in the air entering a liquid. This is measured by the refractive index. The index is a ratio of the velocity of light in the air to the velocity of the light once it has passed into liquid.1 The expected refraction index for D-limonene is 1.4723.

Experimental Section Extraction:

Setup hot water bath at 40-50 °C (not exceeding 50)

Weigh a 50mL centrifuge tube and use a tared beaker

Insert copper coil and spiral 3-4 times using a 30 cm wire

Cut filter paper to size and place on top of Cu coil; reweigh the tube

Grate fresh orange using cheese grate

Add 12g of orange zest, loosely, to tube and record mass

Fill remainder with crushed dry ice (approximately 30g); compact leaving gap with spatula

Seal cap to tube tightly

Add the heated water to a clear plastic cylinder

Place the centrifuge in cylinder and observe the extraction

If the dry ice is not melted then release pressure and add more dry ice

Do not disturb while CO2 is in liquid state

When CO2 is gone, release the pressure and reomove Cu trap

Dry outside of centrifuge

Determine the mass of limonene

Note smell and color

Add 1mL of ethanol to tube and swirl to dissolve

Add solution (noncloudy) to sample tube and obeserve rotation

Read optical rotation and calculate specific rotation and % ee

Turn the index adjuster and align contrast line with crosshairs

Read the refraction index

Correct the reading to 20 °C with formula

Polarimetry:

Weigh the remainder of limonene extract

Refraction:

Place 2-3 drops of limonene on measuring prism using a pipette

Table of Chemicals IUPAC Name

Proper

Molecular

Molar

Melting

Boiling

Chemical

Formula

Mass

Point

Point

(g/mol.) 46.07

(°C) -114.1

(°C) 78.17

Structure Ethanol

C2 H 5 OH

Hazards

-flammable -toxic -irritant -avoid contact with skin and eyes -don’t inhale

Carbon

CO2

44.019

-56.6

-78.46

Dioxide

or ingest -hazardous -potentially explosive -avoid contact with skin and

1-methyl-4-(1-

C10 H 16

1.36.24

-74.35

176

eyes -flammable

methylehtenyl)

-toxic

- cyclohexane

-may cause eye irritation -avoid

contact with skin and eyes -do not ingest

Results Mass (g) Odor Percent Yield Optical Rotation

0.2 Lemon/orange smell actual 0.02 g percent yield= ∗100=2 % ∗100= 10 g theoretical 1g c= =0.1 10 mL T℃

[∝ ]D = Specific Rotation % ee Refractive Index

∝ 10.5 ° =105° = (1∗c) (1∗0.1)

10.5˚ [∝]observed 105° ∗100=90.9 % ∗100= 115.5 ° ∝ [ ] pure 20 n D =n Dt +0.00045 (t−20 ℃ ) =1.4644 % ee=

Discussion The benefit to this method of extraction is that there is little time wasted, as in it is very efficient. The percent yield for the D-limonene was extremely low, at 2%. This is most likely due to the weight that it was divided by for the actual, is the weight of the orange rinds themselves and not the limonene contained in them. The % ee was an extremely high value at 90.9%, meaning that its optical purity was in turn high as well. This allow implies that the stereoisomer present `The refractive index for the D-limonene was expected to be 1.4723. The value found in

the experiment through the refractometer was 1.4644. The difference between the two is approximately 0.0079. These values are relatively close and shows that the refractometer was accurate in its measurement. Conclusion The data has shown that the extraction of the D-limonene was successful since its optical purity was high and the refractive indexes were similar. It also showed that D-limonene has a chiral center, since rotation was observed and a value was returned from the refractometer. This extraction method is used a lot in the cannabis industry. One of the benefits of CO2 extraction is its ability to extract many of the plant’s cannabinoids, hundreds of its terpenes and flavonoids.3 The experiment was successful in extracting the D-limonene from the orange rinds. In addition, it proved that CO2 extraction is ultimately a very clean, effective, green and fast form of extraction. Furthermore, the experiment was successful in the process of determining the % ee of the limonene through the usage of polarimeter. The use of the refractometer was also successful as the number determined experimentally was very similar to the expect value.

References 1.Weldegirma, Solomon. Experimental Organic Chemistry: Laboratory Manual for CHM 2210L and CHM 2211L., 9th edition; Pro-Copy: Tampa, FL, 2020. 2.Wong, Cathy. “The Health Benefits of D-Limonene”. Very Well Health, https://www.verywellhealth.com/the-benefits-of-d-limonene-89444. (Accessed Sept. 28, 202) 3.“Your Concise Guide to CO2 Extraction”. Premium Jane, https://premiumjane.com/blog/whatis-co2-extraction-and-how-does-it-work/#:~:text=CO2%20extraction%20uses %20pressurized%20carbon,as%20a%20tincture%20or%20vaporize. (Accessed Sept. 28 2020)...