CHM557 EXPERIMENT 3 ESTERIFICATION OF VANILLIN The Use of NMR to a Structure. PDF

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UNIVERSITI TEKNOLOGI MARASHAH ALAMLAB REPORTCHM 557ORGANIC CHEMISTRYName : Nurul Yasmin binti Mohd Yuharizan ID No. : 2020980593 Group : AS2532C Experiment : 3 Title : Esterification of Vanillin: The Use of NMR to a Structure. Date of Exp. : 6 th November 2020 Objectives : 1. To synthesize esterific...

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UNIVERSITI TEKNOLOGI MARA SHAH ALAM

LAB REPORT CHM 557 ORGANIC CHEMISTRY

Name ID No. Group Experiment Title Date of Exp. Objectives

: : : : : : :

Nurul Yasmin binti Mohd Yuharizan 2020980593 AS2532C 3 Esterification of Vanillin: The Use of NMR to a Structure. 6th November 2020 1. To synthesize esterification products of vanillin with acetic anhydride under basic and acidic conditions. 2. To determine the melting point of the esterification products of vanillin. 3. To characterize the esterification products of vanillin using IR and 1H NMR spectroscopy.

Introduction Vanillin (4-hydroxy-3methoxybenzaldehyde), an aromatic compound with a good scent, occurs naturally in vanilla beans. Vanillin is commonly used as an aromatic agent for candles, incense, potpourri, fragra nces, perfumes and flavour for drinks and cooking. Vanilin is an organic compound with the molecular formula C8H8O3, a phenolic aldehyde. Vanillin is also a multifunctional compound that has reacted to various products that are ester 1 and ester 2 as shown in the above figure with acetic anhydrite under acidic or basic condition. An example of the esterification of a phenol is the reaction of vanillin with acetic anhydride in the presence of the base. Its IR and NMR spectra can easily characterize the product, which is a white solid.

Procedure Flow Chart A. Basic Condition a. Preparation of Product. In a 250 mL Erlenmeyer flask, dissolve vanillin (1.50 g) into sodium hydroxide (10 percent, 25 mL). It produces a vivid yellow-green solution. Crushed ice (30 g) and acetic anhydride (4.0 mL) added into the flask. A cloudy, milky white precipitate forms instantly upon adding acetic anhydride.

Using a clean PTFE stopper to stop the flask and shake it several times over a period of 20 minutes.

Using a Hirsch funnel or a small Buchner funnel, filter the precipitate and wash the solid with ice-cold water (5 mL). With the ice-cold water (5 mL) repeats the washing process three times. For the setup of a filtration apparatus, refer to Figure 3.1.

Transfer the product (white solid) to the small beaker (50 mL).

b. Recrystallization of the product.

Recrystallize 95 % ethanol from the solid. In a 100 mL conical flask/beaker, pass 95 % ethanol (15 mL) and heat the mixture at 60⁰C in a hot dish.

Stir the mixture and heat it in the boiling solution until the whole solid dissolves. If your hot mixture still contains insoluble solids, add more solvent (ethanol) slowly and continue to heat until completely dissolved.

Cool the mixture for one minute at room temperature and proceed to cool in an ice bath. Crystallization can be caused by scratching up and down the inside of the flask with a glass rod if no crystals have been formed.

Finally, under reduced pressure, filter the crystals using a clean Buchner or Hirsch funnel (see Figure 3.1). Using a spatula at this point to move all of the crystals from the flask to the funnel. Wash the crystals (95 % ethanol) with a small amount of cold solvent. Enable them to dry up by sucking air through the crystals. Move the collected dried crystals into a labeled weighed sample bottle. The product's melting point is below 100⁰C. Do not set the product to dry in the oven.

Determine the product's melting point (77-79⁰C is the literature value) and determine the product's IR and 1H NMR (in CDCl3) spectra as well as vanillin IR spectra.

Figure 3.1: Setup of a Filtration Apparatus

B. Acidic Condition a. Preparation of Product. In a 250 mL Erlenmeyer flask, dissolve vanillin (1.50 g) in acetic anhydride (10 mL) and put a magnetic stir bar in the flask and stir the mixture at room temperature until the solid is dissolved. Stop the flask using PTFE stopper.

Add drop by drop of sulfuric acid (1.0 M, 10 drops) to the reaction mixture while continuing to stir the mixture, and stop the PTFE stopper flask and stir for 1 hour at room temperature. The solution will turn purple or purple-orange in colour throughout the time.

Cool the flask for 4-5 minutes in an ice-water bath after 1 hour and add ice-cold water (35 mL) to the mixture in the flask. The mixture will turn green in color to a pale light.

Tightly stop the flask with a clean PTFE stopper and shake the flask vigorously, almost hard as you would shake while putting your thumb on the stopper, then proceed to cool and shake the flask to induce crystallization.

When you can see tiny firm clumps separating from the cloudy liquid and settling at the bottom of the flask, crystallization has occurred. Using a Hirsch funnel or a small Buchner funnel, filter the solid or crystal and wash the solid with ice-cold water (5 mL). The ice-cold water (5 mL) repeats the washing process three times. For the setup of a filtration system, refer to Figure 3.1, and then pass the product (white solid) to the small beaker (50 mL).

b. Recrystallization of the Product. Recrystallize 95 % ethanol from the solid. In a 100 mL conical flask/beaker, pass 95 % ethanol (15 mL) and heat the mixture at 60⁰C in a hot dish. Stir the mixture and heat it in the boiling solution until the whole solid dissolves. If the hot mixture still contains insoluble solids, add more solvent (ethanol) slowly and continue to heat until completely dissolved.

Cool the mixture for one minute at room temperature and proceed to cool in an ice bath that has a little bit of salt in it. Crystallization can be caused by scratching up and down the inside of the flask with a glass rod if no crystals have been formed.

Finally, under decreased pressure, filter the crystals using a clean Buchner or Hirsch funnel (see Figure 3.1). Using a spatula at this point to move all of the crystals from the flask to the funnel. Wash the crystals (95 % ethanol) with a small amount of cold solvent. Enable them to dry up by sucking air through the crystals. Move the collected dried crystals into a labeled weighed sample bottle. The product's melting point is below 100oC. Do not set the product to dry in the oven.

Determine the product melting point (literature value is 90-91⁰C) and determine the product IR and 1H NMR (in CDCl3) and vanillin IR spectra.

Results and Observations A.

Basic Condition Results: a.

Weight of product

:

b.

Melting point of the product

: 77-79ºC

c.

Appearance of the product

: White crystal solid form

e.

IR data (in Table): i. ii.

1.1123 g

Vanillin Product Wavenumber (cm-1) 2968 1758

f.

1

Type of bond (group) C-H C=O

H NMR data of the product (in Table): Chemical shift, δ (ppm) 9.96 2.38 4.04

Multiplicity Singlet Singlet Singlet

Number of hydrogen 1 3 1

Type of proton ROCH OOCH3 OH

Observations: Write the observations such as colour changes, colour of the precipitate etc during the period of experiment. Steps Dissolve vanillin in sodium hydroxide Added acetic anhydride Final product form

Observations Bright yellow green solution Cloudy, milky white precipitate White crystal formed

Calculations and Task: a. Calculation of theoretical yield of product.

b. Percentage yield of product.

c. Name the products. 4-formylphenyl acetate/ vanillyl acetate

B.

Acidic Condition Results: a.

Weight of product

: 2.3979 g

b.

Melting point of the product

: 90-92ºC

c.

Appearance of the product

: White solid crystal form

e.

IR data (in Table): i. ii.

Vanillin Product Wavenumber (cm-1) 1753 1160

f.

1

Type of bond (group) C=O C-O

H NMR data of the product (in Table): Chemical shift, δ (ppm)

Multiplicity

4.00 2.23, 2.34 7.24, 7.27

Singlet Doublets Doublets

Number of hydrogen 1 3 1

Type of proton OH OOCCH3 Benzene ring

Observations: Write the observations such as colour changes, colour of the precipitate etc during the period of experiment. Steps Observations Stir mixture under Colorless to purple/purple orange room temperature for 1 hour Added ice-cold water Purple/purple-orange to pale green Final product form White color formed

Calculations and Task: a.

Calculation of theoretical yield of product.

b.

Percentage yield of product.

c.

Name the products and draw their reaction mechanisms. (4-Acetoxy-3-methoxyphenyl) methylene diacetate

Discussion In this experiment, the primary aim was to be accomplished by specifying each compound for acidic and basic conditions. The reaction will generate tri-ester basis on the theoretical in acidic condition. The reaction will produce 4-Acetoxy-3-Methoxybenzaldehyde (Vanillyl Acetate) whilst in basic condition. Analysis of the functional group and product structure was performed using IR spectroscopy and NMR spectroscopy. The performance structure is shown below. The mass of the basic product collected was 1.1123 g from the mass theoretical product capable of producing is 1.9148 g, of which only 58.09%. Due to the loss of the substance during transition between procedures, the percentage yield was lower than the theoretical mass and could also induce incompleteness in the reaction. While the mass of the product obtained for acid condition was 2.3979 g of theoretical mass product capable of 2.9215 g of product, of which only 82.08%. The percent of yield is more than half percent means the yield of product was successful. There were variations between the acid melting points and the reactions that were basecatalyzed. Based on the theoretical fact, the variety of melting points for basic condition product is 77-79 ⁰C. Although the theory-based range of melting points for the acid condition product is 90-92 ⁰C, the range variance shows impurities present in the product. The molecular weight and structure bonding present in the product can affect the melting point of the product. Based on the theoretical proof, the molecular weight of the acidic condition product was 296 g/mol higher than the reaction product of the basic condition, 194.18 g/mol. The greater the compound's molecular weight, the greater the compound's melting point. The impurity of the product from the reaction may also be triggered by it. Even, recrystallize has been done. The resulting IR spectra illustrate the absorption of the acid and base-catalyzed reactions, respectively. Both contain a high peak that corresponds to a C=O stretch around 1750 cm-1. The presence of C=O bonds in the compound has been indicated. Ester fictional group was represented the product. In acid condition product, IR spectrum also show the peak at 1160 cm1 to indicate C-O. The NMR showed that the basic product is vanillin acetate and the acidic product is vanillin triacetate. One hydrogen is present at 9.97 ppm for basic conditions, and this showed that the substance produced consists of aldehyde. This value is absent in the acidic product, indicating that the substance formed does not contain an aldehyde group. Product for both reactions also give NMR spectrum peak at range 4.00 ppm which is indicate the -OH bond.

Conclusion Throughout the experiment, it was possible to recognize the commodity. The acid or base esterification reaction produces various products. The acid-catalysed product tends to produce (4-Acetoxy-3-methoxyphenyl) methylene diacetate while basic reaction produces 4-Acetoxy3-Methoxybenzaldehyde. For the base and acid catalysed reactions, the percent yield of product for the reactions was 58.09% and 82.08% respectively.

References 1. Solomon, Fryhle, Snyder (2016). Organic Chemistry Twelveth Edition, Wiley, United State Of America. 2. Gallage, Nethaji J., & Møller, Birger L. (2015). Vanillin–Bioconversion and Bioengineering of the Most Popular Plant Flavor and Its De Novo Biosynthesis in the Vanilla Orchid. Molecular Plant, 8(1), 40-57. doi:https://doi.org/10.1016/j.molp.2014.11.008

Questions 1.

Under different reaction media, vanillin undergoes esterification with acetyl chloride yielding two different products. O H

O

Basic or acidic medium Cl

HO

?

OCH3 Vanillin

a.

b.

c.

Based on the IR spectrum of vanillin, at what range should you observe the absorption signal of the hydroxyl group? It should be in range of 3300 – 2500 cm-1 with broad peak. Based on its 1H NMR spectrum, what is the expected chemical shift value for the methoxy group (OCH3)? What is its multiplicity? According to OCH3 bond, it will be between 2.1-2.5 and have singlet multiplicity. Draw the structures of the major products for the esterification of vanillin with acetyl chloride in: i. ii.

2.

10% NaOH solution 1.0 M H2SO4 solution

Write the mechanism for the reaction between vanillin and acetyl chloride in 10% NaOH solution.

Appendix 1: IR spectrum in Acid Condition

C-O C=O

Appendix 2: IR spectrum in Basic Condition

C-H

C=O C-O

Appendix 3: NMR Spectrum for Acid Condition

Appendix 4: NMR Spectrum for Basic Condition...