Organic chemistry 2 lab report #10 full doc. PDF

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Laboratory report for organic chemistry II with details of experiment and trials we conducted to obtain successful results. Very helpful....

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Alyssa Grecz Lab Partners: Maria and Melanie Yu Yan Experiment 10: Wittig reaction – Synthesis of trans-9-(2-phenylethenyl) anthracene

I.

Introduction To begin with, this experimentation involved an essential reaction known as the Wittig reaction, which is a combination of molecules employed in order to generate an alkene. There are numerous important functional groups that are included in the Wittig reaction which are aldehydes, ketones and our desired product, containing the alkene. The alkene group is the functional compound that is converted through the help of a Wittig reagent, which in this case is the triphenylphosphonium chloride, therefore, the alkene and oxide compounds are the intended creations.1 As observed through this experiment, the functional groups aldehyde or ketone are required as they are the compounds being transformed, as well as the proper reagent, which must be a phosphonium particle for this reaction to occur through heat. For example, we may begin with a phosphonium ion and add that to cyclohexanone, known as the “ylid”, which will develop into an alkene based off the carbonyl group from the starting solvent.2 The modified Wittig reaction, also referred to as the Horner-Wadsworth-Emmons modification, is a specific reaction that contains a carbon atom with a negative charge which takes the place of the “ylid”, as it is a more proper nucleophile, dissolves in H2O and can produce sufficient yields.3 It’s significant to modify the reaction in order to develop the required product as it proceeds through H2O and is dried thoroughly at last to gain the entire alkene production. The modified and unmodified Wittig Reactions are both crucial in synthetic applications based on their unique techniques stated above for generating natural and safe materials, just depending on what is being created and which reaction is necessary. Different carbonyl groups are consistently carried out and prepared throughout these reactions, developing the appropriate product. The mechanism for this study is located below as it

exhibits the deprotonation through sodium hydroxide, the pi bonds being formed, and the aldehyde being transformed into an alkene. The potential, side products are also located below which demonstrates what can form if there is sodium hydroxide remaining in the mixture and if H2O reacts abruptly.

II.

Experimental Section

First, we placed 0.3 grams of benzyltriphenylphosphonium chloride, 0.116 grams of 9anthraldehyde, 1 mL of dichloromethane, and a magnetic stir bar into a vial. We performed thin layer chromatography and noted it. We then added 0.4 mL of 50% sodium hydroxide while mixing aggressively for 30 minutes and took another TLC.

III.

We continued to mix the solution until the aldehyde dot was absent on the TLC plate. Next we placed 1.5 mL of H2O and 1.5 mL of dichloromethane to the vial and mixed it strongly. We placed the organic layer in a tube and removed the aqueous layer with 1 mL dichloromethane. We dried the dichloromethane solutions in CaCl2 pellets.

We withdrew the dichloromethane, rinsed the drying agent, and the solvent is detached through vacuum filtration. We placed 3 mL of 1-propanol into the flask with the solid, warmed it and shifted the solution for crystallization. Once cooled in an ice bath, we gathered the product on the funnel. Lastly, we found the mass, melting point, IR and 1H NMR data.

Table of Chemicals

Chemical Name

Chemical Formula

Molar Mass

Melting Point

Boiling Point

Benzyltriphenylphosphoniu m Chloride

C25H22ClP

388.9 g/mol

337°C

N/A

9-anthraldehyde

C15H10O

206.24 g/mol

103-105°C

419.7°C

Dichloromethane

CH2Cl2

84.93 g/mol

-96.7°C

39.6°C

Sodium Hydroxide

NaOH

39.997 g/mol

318°C

1,388°C

Organic Chemical Structure

Hazards/Toxicity

Hazardous if exposed to skin, eyes, if ingested or inhaled. Can be fatal. Can cause irritation to skin, eyes, if ingested or inhaled. Very hazardous with exposure to skin, eyes, if ingested or inhaled. Can be carcinogenic. Can be hazardous if exposed to skin, eyes and mucous membrane. Can

1-Propanol

C3H8O

60.09 g/mol

-126°C

97°C

Trans-9-(2-phenylethenyl) anthracene

C22H16

280.4 g/mol

130-132°C

491.4°C

Mass (g) 0.053

Crude Rf Value 0.57

IV.

cause temporary hair loss. Hazardous if exposed to skin, eyes, if ingested or inhaled. Can irritate respiratory tract and cause dizziness. Hazardous if exposed to skin, eyes, if ingested or inhaled.

Results

Product Trans-9-(2-phenylethenyl) anthracene



Desired Rf Value 0.91

Melting Point 133-134°C

Percent Yield 33.9%

Percent Yield: (Actual / Theoretical) x 100 -

9-anthraldehyde: (0.116 grams / 206.24 g/mols) = 0.00056 mols

-

Trans-9-(2-phenylethenyl) anthracene: (0.053 grams / 280.4 g/mols) = 0.00019 mols

-

Percent Yield: (0.00019 mols / 0.00056 mols) x 100 = 33.9%

V.

Discussion First and foremost, the purpose of this study was to execute a Wittig reaction with the starting substance, phosphonium chloride, with the use of a powerful base, in order to generate the complete and final alkene production. The melting point of our final product, trans-9-(2-phenylethenyl) anthracene, was recorded at approximately 133-134°C, whereas the literature value is 130-132°C. This melting point indicates that our product was refined, consisting of the one substance required and was completely transformed thoroughly. The thin layer chromatography was successful and beneficial as it displayed the removal of the aldehyde dot shown on the plate. The Rf value of our alkene product was higher than the initial, 9-anthraldehyde, which was relatively expected being that the aldehyde was removed, and our solution began to convert to the desired product as the

strong base came into effect. The percent yield I calculated came out to roughly 33.9%, which is definitely low as the product weight was noted at 0.053 grams. This may be due to the fact that some product was lost during the transferring of chemicals or as the solvent experienced vacuum and crystallization. The IR spectrum presented above expresses that the complete product was fully developed, being that there were no distinct peaks between 1500 cm-1 to 2000 cm-1, therefore, the aldehyde was removed. It’s also very victorious that there were no fine peaks in the 3000 cm-1 range because it reveals that weren’t any undesired creations that do not belong. Based on the 1H NMR data, all of the following peaks presented above are in the 6-8 ppm range, which is acceptable due to the aromatic rings and hydrogen atoms that are included in our final product. The integrals within each proton peak are represented well as it displays the alkene product conversion. For each unique spectrum, the formation is determined by observing each peak separately and labeling what that peak means, and then combining all of the peaks content together in order to obtain the fully developed compound necessary. The specific functional group that is shown within the IR spectra is the carbonyl group that is developed from the reagent. Generally, the Wittig reaction was successfully executed, and the product was shown through the spectrums and visually. VI.

Conclusion Overall, the main objective of this assessment was to create the pure product, trans-9-(2phenylethenyl) anthracene, through the use of a Wittig reagent, powerful base and thin layer chromatography. The information acquired through this trial has revealed that the Wittig reaction is successful and can undergo several techniques in order to gain the desired product in a safe manner. The Wittig reaction can be employed in real life

situations for developing natural and efficient materials, such as, food, medications and beverages, which helps keep our society safe and functioning.4 This laboratory experiment did accomplish precisely what it set out to do being that trans-9-(2phenylethenyl) anthracene was capable of undergoing conversion while acquiring a melting point, IR and 1H NMR data. From this study, I have learned what a Wittig reaction consists of and how to perform a Wittig reaction in an efficient, harmless way.

VII.

References 1

Weldegirma, S. Experimental Organic Chemistry, Laboratory Manuel: CHM 2210L and

CHM 2211L; 8th edition. Pro-Copy Inc.: Tampa, 2018; pp. 118-119 2

Master Organic Chemistry. Wittig Reaction.

https://www.masterorganicchemistry.com/2018/02/06/wittig-reaction/ (accessed April 7, 2020)

3

AdiChemistry. Wittig Reaction.

https://www.adichemistry.com/organic/namedreactions/wittigreaction/wittig-reaction1.html (accessed April 7, 2020) 4

Chemistry Europe. Applications of the Wittig Reaction on the Synthesis of Natural and

Natural-Analogue Heterocyclic Compounds. https://chemistryeurope.onlinelibrary.wiley.com/doi/abs/10.1002/ejoc.201800523 (accessed April 7, 2020)...