D- Limonene - Grade: A PDF

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LABREPORT FOR EXPERIMENT 5...

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Experiment 5: Liquid CO2 Extraction of D-Limonene from Orange Rind Yen Ngo Partner: Maya Subramanian TA: Linette Harding CHM2210L.015 September 30, 2019

Introduction: Liquid extractions are considered as one of the most prevalently used techniques in compounds separation. This week’s objective was to successfully isolate D-Limonene from orange rinds. Industrially, D-Limonene is commonly extracted through different methods such as steam distillation, organic solvent, and cold pressing. The last method is through liquid CO2, and for this week’s experiment liquid CO2 was utilized to perform D-Limonene extraction. These processes are often used to extract essential oils which exists in the forms of terpenoids and terpenes. They are loosely connected isoprene units organized in a head to tail manner. For each isoprene units that a terpenoid holds, it is given a particular name. As an example, two isoprene units is called a monterpene, which subsides in orange rinds giving off the essential oils distinct fragrances. CO2 was selected as the solvent because it has the ability to reach a supercritical point where it can act as both a liquid and gas. In return, this yields a product that is not denatured. Additionally, CO2 yields no environmental hazards, is nontoxic, nonflammable, and easily accessible. Polarimetry is the practice of calculating the extent in which a compound interacts with vibrating light waves in one plane. With that information, it is used to determine which direction the light has rotated towards, if any. Chirality is extremely important in polarimetry. If a compound is said to be chiral, then it rotates either to the left or right. If it rotates like so, then the compound is deemed optically active. A chiral center is defined as having four different groups directly bonded to the central carbon. The main objective of polarimetry is to determine the observed optical rotation, a value used for comparisons between an extracted substance and a pure substance. This results are conveyed in terms of enantiomeric excess or optical purity.

Refractometry is the practice of determining the refractive index of the desired compound. The refractive index signifies a positive constant ratio involving the velocities of the light in the air and in liquid. This value should always be greater than one. The refractive index can be obtained through using information such as the yellow D-line in the sodium vapor lamp, and the temperature. The yellow D-line creates light that has a wavelength at 598nm. Since, white light is used instead of sodium vapor light, a temperature modification is applied. For each degree above 20 ℃ , 0.00045 is added 4.

Experimental:

- Setted up hot water bath to

approximately 65, no more than that. -Weighed 50ml centrifuge tube with just lid. -Copper coil along with filtered paper was inserted into tube. -Reweighed the newly assembled tube with copper coil, filter paper, and lid. -Recorded each weight.

-Added in approximated 30g of dry ice or until tube was full. -Made sure cap was on tight and snugged. -Applied parafilm over the top for reinforcement.

-Copper

coil , filtered paper, and orange rinds were removed carefully making sure that the DLimonene was not disturbed. -Any remaining orange rind residues were removed. -Weighed the centrifuge with DLimonene extract and lid in a tared beaker

-Ran the refractometer test on D-Limonene. -The percentage yield, optical rotation, specific rotation, ee %, and refractive index was detrmined.

-Grated

and weighed 10g of organge rinds and loosely added product into centrifuge tube. -Weighed the newly assembled tube containing now the coil, filter paper, orange rinds and lid. -Total mass of orange rinds was calculated.

-Poured water bath into large plastic graduated cylinder and quickly inserted centrifuge tube into cylinder. -Closed the fume hood and observed for reactions to occur until all the CO2 had evaproated.

-The weight of D-Limonene extract was determined. -The apperance and odor was noted. -The extracted D-Limonene and stock D-Limonene wee both ran trhought the polarimeter.

Chemicals Table 1: Chemicals Used Chemicals &

IUPAC

Appearances

their Structures

1-methyl-

-Citrus

1,4-(1-

scented

methyletheny l)-

Molecular

Molar

Melting

Boilin

formula

Mass

point

g

C10 H 16

136.23

-40 ℃

point 168 ℃

g/mol

Hazards

Skin sensitivity,

-Light yellow

respiratory

tinted

irritation,

cyclohexane Carbon

Pale and

Dioxide

odorless

44.01

-56.6

Critic

combustible Skin

g/mol

℃

al pt=

sensitivity

solids, same

31

(frostbite),

as it

℃

respiratory

CO2

evaporated.

irritation, dizziness, suffocation, may explode under

Ethanol

-Clear liquid -Pleasant odor

CH 3 CH 2 O

46.07

-114.1

78.5

pressure. Skin/eyes

g/mol

℃

℃

sensitivity, respiratory irritation,

flammable, poisonous if ingested.

Results: Table 2: Weight measurement data

Items

Weight in grams

Centrifuge tube

1.96

Centrifuge tube with copper coil and filtered paper

3.03

Orange rinds

10.24

Centrifuge tube with copper coil, filtered paper, and orange rinds

13.27

Centrifuge tube with extracted D-Limonene

1.45

Table 3: Data obtained through experiment and calculations

Chemical

Mass

Odor &

(g)

Appearance

% yield

Optical

Specific

Rotation

Rotation

ee %

Refractive Index

(Degrees) (Degrees)

-Citrus

Can’t be

Limonen

scented

determined,

e

-Light

mass of D-

yellow tinted

limonene

D-

>0.01

was negative

Calculations:

93o

120o

80.5 2%

1.316

Percentage yield: Cannot be determined due to D-Limonene exhibiting a negative mass.

percentage yield=

actual x 100 theoretical

Centrifuge tube with D-Limonene – Empty centrifuge = D-limonene’s mass in grams 1.45 – 1. 96 = -0.51g  Weight cannot be negative. Specific Rotation:

[ α ]TD ℃= α

l∗c

Cannot be calculated due to D-Limonene weight being negative. Enantiomeric Excess (ee %):

[α ] observed x 100 = ee % [α ] pure 93 x 100 = 80.5195% 115.5 Refractive Index: n D +0.00045 ( t−20 ℃ )=nD t

20

21

1.314 D +0.00045( 21−20 ℃ ) =1.316

Discussion: D-Limonene extraction through the usage of liquid CO2 is faster and more beneficial for the environment in comparison to steam distillation. Liquid CO 2 yields no environmental hazards, is nontoxic, nonflammable, nonreactive with most compounds and is easily accessible. Furthermore, CO2 has tunable solubility and the ability to reach a supercritical point where it can act as both a liquid and gas. However, with steam distillation there is a higher chance of contamination, and the chemicals used can negatively affect the environment and requires more intensive care and disposal. Additionally, the right solvent could be expensive and not as readily available compared to CO2. CO2 is initially removed from the atmosphere, therefore there is no net effect. A polarimeter measures optical rotation, which is the degree a solution rotates a ray of plane polarized light 4. Optical rotation depends on a variety of factors including concentration, path distance, temperature, wavelength and the solvent used. While, specific rotation is measured in degrees spotted upon a molecule passing through a path distance of 1 decimetre at a specific temperature. Specific rotation is dependable on the temperature, light wavelength, solvent, and concentration 1. The specific rotation for the extracted D-Limonene is approximately 120o and the specific rotation calculated was 93o which came close to the value expected 3. Our ee % value was calculated to determine the purity of the product. The results yielded an ee % value of 80.25% which is an acceptable value because it falls within the 80-100%. If it were to have fallen outside of the indicated range, then the product can be deemed as impure. The refractive index calculated was 1.316, while the actual refractive index of DLimonene is said to be 1.4727 3. This minor difference in value could have stemmed from impurities. For example, the D-Limonene solution was contaminated during the removal of the

coil, filter paper, rinds, and CO2. The filter paper could have also been placed incorrectly resulting is poor filtration. The specific rotation and percentage yield of the extracted DLimonene could not be determined due to a negative value in mass for the solution. It is impossible for the weight of the centrifuge tube with the D-Limonene extracted to be less heavy than the original centrifuge tube with just the lid. This could have been a result that both of the weighing scales were broken and giving false information. At times it wouldn’t even show a value, just an error message. Since the scale was malfunctioning, the mass of the solution was going to be calculated by subtracting the empty centrifuge tube from the final tube containing the D-Limonene. However, the value ended up being negative skewing the results.

Conclusion: Overall the purpose of the experiment was achieved. D-Limonene was successfully extracted from orange rinds using liquid CO2 resulting in a positive start to green chemistry. Liquid CO2 is a safer extraction alternative due to its nontoxic, nonflammable, low reactive levels and its’ ability to behave both as a liquid and gas when put under a supercritical condition. No harsh chemicals were used, therefore there is no environmental effects. Polarimetry was utilized to compare the optical rotation degrees between extracted D-Limonene against the stock solution of D-Limonene. This information is then use to calculate the enantiomeric excess value to further clarify the purity of the D-Limonene. Ultimately, a refractometer was utilized to find the constant refractive index between the extracted D-Limonene and its’ stock solution and its’ literature values. Once again, a comparison is drawn and a purity conclusion is formed. The specific rotation for the extracted D-Limonene is approximately 120o and the specific rotation calculated was 93o which came close to the value expected. The ee % value of 80.25% which is a good

indication for purity since it falls within the suggested values of 80-100%. The refractive index calculated was 1.316, while the actual refractive index of D-Limonene is said to be 1.4727 3. This minor difference in value could have stemmed from impurities caused by errors during the experiments. Like previously mentioned, the lab effectively carried out its’ purpose. D-Limonene was successfully extracted and used for comparisons. However, the weighing scale issue created a lot of problem during calculation due to incorrect weight. Therefore, this was the only portion deemed unsuccessful. Liquid Co2 extraction is not only performed in the laboratory, but is beneficial for many companies such as those producing perfumes, colognes, and fragrances. Another example would be the extraction of other substances such as caffeine, herbs for herbal supplements, and how pesticides can be removed from plants in order to restore its’ nutritional contents 2.

References: 1. Ashenhurst, J. (2019). Optical Rotation, Optical Activity, and Specific Rotation. [Online]. Available at: https://www.masterorganicchemistry.com/2017/02/07/optical-rotationoptical-activity-and-specific-rotation/ (Accessed Sep 30, 2019). 2.Cool Clean Technologies. (2015). Liquid Carbon Dioxide for Selective Extraction. [Online]. Available at: http://coolclean.com/2015/05/15/liquid-carbon-dioxide-for-selectiveextraction/ [Accessed. 30 Sep. 2019] 3.PubChem. (2018). D-Limonene. [Online]. Available at: https://pubchem.ncbi.nlm.nih.gov/compound/___-Limonene#section=Top [Accessed 30 Sep. 2019] 4.Weldegirma, S. (2019). Experimental Organic Chemistry. 8th ed. Tampa: University of South Florida, pp.25-31....