Banana oil Lab Report PDF

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Synthesis of Banana Oil

Alsamman 1

Purpose The purpose of this experiment is aimed at synthesizing 3-methylbutyl acetate (isopentyl acetate) via an esterification process between isopentyl alcohol (3-methylbutanol) and acetic acid with concentrated sulfuric acid as the catalyst. The process has been made using a reflux apparatus, a separatory funnel, drying agents, and simple distillation to obtain its boiling point, and separate the product. The identity of the Isopentyl was proven later by the usage of H NMR and IR. Reaction Scheme Esters are usually a class of compounds that are found in nature and are characterized by a sweet smell (Zhuowang & Xu, 231). Notably, lbow molecular weight esters are often associated with essential oils.

Acetic Acid

Isopentyl Alcohol

Isopentyl Acetate Figure 1

Alsamman 2 Mechanism: Some of the key aspects of the esterification mechanism in the process here include protonation of the carbonyl oxygen and the final addition of the alcohol to form a tetrahedral intermediate. The proton transfers here form water and also create a good leaving group. Additionally, there is also deprotonation of the carbonyl oxygen in order to form the final product.

Alsamman 3

Alsamman 4 Procedure The procedure followed was as described in the Wissinger Manual (2020). In a 50 ml round bottomed flask with stir bar, 5 grams of isopentyl acetate and 8.5 mL of frozen glacial acetic acid was added. The solution then was taken to the fume hood and stirred carefully while adding drops of the conc sulfuric acid. A reflux apparatus was created, and the mixture was refluxed for about 60 minutes. The mixture was left to cool down back to room temperature after the reflux step has ended. Then the solution was poured into a separator funnel and 10 mL of de-ionized water was added later and mixed within the separatory funnel. The aqueous layer was drained without losing the organic layer on top. Then 10 mL of aqueous sodium bicarbonate was added in order to get rid of any remaining acetic acid. This step has been repeated till the solution was fully neutralized and its PH was confirmed using a litmus paper to indicate that no acid was left. The layer was then washed using Sodium Chloride (brine) in order to facilitate drying. Then the ester was transferred afterward to a 50 mL Erlenmeyer Flask and dried for 10 minutes using anhydrous magnesium sulfate. A glass wool was place on top of the layer then transferred into a 25 mL of rounded bottom flask that had a stir bar in it using a pasture pipet. The solution was distilled using a simple distillation apparatus, and a heating mantle (variac 55-60). After the boiling point range has been obtained the flask was left to cool down, weighed and then an IR and NMR samples were submitted for identification. Reagents Table Source: Acros

Acetic Acid

Isopentyl Alcohol

Sulfuric Acid

Isopentyl Acetate

Molecular Weight (g/mol)

60.05

88.15

98.07

130.19

Mass (g)

8.91

5.00

2.20

7.38

Alsamman 5

Volume (ml)

8.5

6.25

1.2

8.48

Density (g/ml)

1.096

0.8

1.83

0.87

Moles

0.148

0.0567

0.0227

0.0567

Boiling Point (BP)

117-118

130

290

149

Solubility

Hazards and handling

 Soluble in Soluble in water water  Miscible  Miscible solubility solubility – With ether, Alcohol, alcohol, glycerol, benzenes, Carbon tetra chloroform chloride and oils  Insoluble in Carbon disulfide  Flammable  Can cause severe skin  Potentially harmful and eye when inhaled damage  Skin  Highly irritation flammable  Serious eye Precautions irritation  Skin dryness  If it comes in contact with Precautions your eyes, rinse well  Keep away from heat  Wear sources protective gloves when  Move to fresh air if handling inhaled  Wash skin with a lot of water if it comes to contact



Soluble in water  Miscible solubility in others  Miscible with alcohol



Dangerous if swallowed. Seek medical attention  If comes in contact with eyes, rinse with a lot of water  Rinse with lots of water to avoid skin irritation if it comes to contact







Soluble in water  Miscible with alcohol and ether

Flammable liquid. Keep away from direct fire  Rinse your eyes with a lot of water if it comes in contact

Alsamman 6 Observation and Results During the synthesis reaction in the round bottomed flask, not much was observed until the catalyst sulfuric acid was added When the acid was added, there was some odor from the flask and some bubbles has formed. When heat was applied, it got a little foggy at the beginning, but it took around 45 minutes before the solution started turning light brown then towards the end it turned into darker orange. The tubes connected to the reflux apparatus were leaking water, which somehow made the solution not boil till the end although it was hot, and the ester smell was strong. When the mixture was added to the separatory funnel, nothing was observed till some sodium bicarbonate was added to the organic layer. Some effervesce and CO2 was observed and pushed the stopper out of the separatory funnel which made most of the organic layer spill out. In the final steps of the experiment, the organic layer was washed away with the sodium chloride while the organic layer turned increasingly yellow and thick. Drying was done with the anhydrous magnesium sulfate. Upon distillation, the final colorless one drop product with a banana smell was formed, the drop then was mixed with CDCl3 and HNMR was obtained, however the IR was obtained from a lab partner (Kendra Sandkamp) because of the lack of products. Table 1 Product

Actual Yield

Theoretica l Yield

% Yield

Corrected Yield%

Observe d BP Celsius

Literature BP Celsius

Appearance

Isopentyl acetate

1 drop

7.8 grams

1

99

125

142

Clear, colorless liquid with banana smell.

Alsamman 7 Yield Calculations: none was made because of the lack of products; however, those are the calculations of the theoretical yield. Acetic Acid

8.5 ml x

8.91 x

1.048 g =8.91 1 ml

1 mol =0.178mol 60.05 g

Isopentyl Alcohol

5g x

1ml =6.25 mL 0.8 g

5g x

1mol =0.0567 mol 88.15 g

Isopentyl Acetate

0.0567 mol x

7.38 g x

130.19 =7.38 g 1 mol

1ml =8.98 mL 0.87 g

Sulfuric Acid

1.2 ml x

1.83 g =2.20 g 1 ml

2.20 g x 1

mol =0.0224 mol 98.07

Alsamman 8 Table 2.

H NMR Spectrum (300 MHz, CDCl3, for Isopentyl Acetate) Chemical Shift, ppm

Splitting Pattern

J value, Hz

Integration value, cm

Relative #H’s

Ha

0.93-0.83

Doublet

30

1.00

6

Hb

1.50

Triplet

9

0.34

2

Hc

1.66

Septet

6

0.16

1

Protons, Hx Mohrig, 2014

(multiplet) Hd

2.01

Singlet

------

0.47

3

He

4.09

Triplet

15

0.33

2

Ha’

3.65

Triplet

3

0.08

2

J values calculations Ha

( 0.93− 0.83 ) x 300=30 Hb

( 1.50−1.47 ) x 300=9 Hc

( 1.70−1.68 ) x 300 =6 He

( 4.14 − 4.09) x 300=15 Ha’ (C-O-H)

( 3.66− 3.65 ) x 300=3

Purity percentage can’t be obtained because of the lack of product mass

IR of Isopentyl Acetate

Alsamman 9 Table 3. Bond Variation

Frequency (cm-1)

Intensity

A

-C -H Stretch

2958.2

Medium to Strong

A

C=O Stretch (ester)

1793.3

Strong

A

CH2 Bend

1465.9

Medium to weak

A

CH3 Bend

1366.5

Medium to weak

A

O-C=O Stretch (ester)

1228.1

Strong

A

O-CH2 Stretch

117.15

Strong

Compound Source: Mohrig, 2014

Discussion and Conclusion In the first steps of the experiment where the mixture of glacial acetic acid and isopentyl alcohol remained clear till the catalyst was added, a reflux was enhanced to trigger the reaction. After the heating, possible isopentyl alcohol, water, isopentyl acetate, acetic acid and sulfuric acid were left in the flask. Further, the Isopentyl acetate was separated by the addition of water. Both the remaining sulfuric acid and Isopentyl acetate dissolved in water. Any remaining acids in the mixture were reacted with sodium bicarbonate and thereby producing carbon deoxide. This explains the effervesce observed towards the end of the experiment. The addition of sodium chloride was done in order to extract water from the ester mixture. Further to this, magnesium sulfate was added to ensure that all H2O was completely gotten rid of (Zhuowang & Xu, 232). Distillation have been done to ensure that the end result was a pure ester and to get rid of any remaining starting material through separation according to the difference in their boiling point.

Alsamman 10 In order to confirm that the final product obtained in the experiment contained only isopentyl acetate, an IR and NMR spectroscopy were performed. During the NMR for the synthesized product, the He signal shifted downfield at 4.04 ppm, confirming the indeed the product was in line with our expectations that there was a carbon linked to an ester. The downfield shift was a confirmation indeed that there was some present isopentyl acetate. This corresponded with the methyl that is attached directly to the carboxyl group. In the analysis, two peaks that did not correspond to the isopentyl acetate were obtained. One of them have been due to the presence of some residue alcohol in the end product, the other have been caused by the solvent CDCl3 used for NMR purposes. CDCl3 wasn’t taken into account for purity calculations though. For the IR analyses, several peaks here were shown. This was a confirmation that there was some presence of the isopentyl acetate at 1742.6 cm-1, probably caused by the C=O vibration in the resulting ester. At 1244.2 cm-1, the stretch have been caused by the carbonyl stretch. Side reactions and errors during the experiment lead to a low yield as a result. Indeed, every single spilled drop and leaking that happened through the reflux apparatus resulted with losing the product and it vanishing further through distillation, and drying thereby leading to a low yield. Notably, there were some errors that have arisen in the course of the experiment. For instance, lower boiling points were recorded during the experiment as compared to the literature values. This could have been due to some presence of alcohol in the ester (LAN et.al 34). If the solvents were handled more carefully, side reactions could be prevented. Additionally, it would’ve been a good idea to reflux the solution for a full 75 minutes, and to replace the tubes

Alsamman 11 linked once realized that they are leaking. Waiting for the reaction to stabilize before mixing it further would’ve prevented the CO2 from pushing the stopper of the separatory funnel. If errors of the experiment were taken care of, there could be an increase in the total amount of ester recovered. Lastly, in order to avoid further errors, placing too much final product in the NMR tube isn’t a good idea since it saturates samples (LAN et.al 44). Overall, this experiment was considerably successful. The sulfuric acid catalyzed the reaction where the esterification of a carboxylic acid and an alcohol via reflux and drying took place. The experiment gave relatively good results. Finally, an IR and H NMR analysis confirmed that indeed the end result was isopentyl acetate.

Alsamman 12 Literature Cited Acros.com, Thermo Fischer Scientific, acros.com/. LAN, Cui-ling, et al. "Study on the Synthesis of Isopentyl Acetate Catalyzed by SO_4~(2-)/TiO_2 Solid Superacid." Journal of Youjiang Teachers College For Nationalities Guangxi 6 (2004). Mohrig, Jerry R., et al. Laboratory Techniques in Organic Chemistry: Miniscale, Standard Taper Microscale, and Williamson Microscale. W.H. Freeman and Company, 2014. Wissinger, Jane. Organic Chemistry: A Green Chemistry Approach. 2nd ed., Hayden-McNeil, 2020. pp.57-60 Zhuowang, Xu. "STUDIES ON CATALYTIC SYNTHESIS OF ISOPENTYL ACETATE BY HETEROPOLY ACID [J]." Natural Science Journal of Harbin Normal University 4 (2004)....