Reduction of Vanillin with Sodium Borohydride: A Chemistry Experiment, Cheat Sheet of Organic Chemistry

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University Of Botswana CHEMISTRY DEPARTMENT SURNAME: MOSIMENYANE INITIALS: M. O STUDENT ID: 201902080 DAY: FRIDAY, 1500 – 1800 HRS EXPERIMENT 334.4: REDUCTION OF VANILLIN WITH SODIUM BOROHYDRIDE

ABSTRACT

The percentage yield of vanillin to vanillyl alcohol was discovered to be 51.4 % utilizing Sodium Borohydride as the reducing agent, the melting point was found to be in the range of 94.0 - 98. degrees, and the TLC plate for the product was obtained. The product was white crystals with a shiny appearance. AIM The aim of this experiment is to carry out reduction of vanillin to vanillyl using sodium borohydride (NaBH 4 ) as reducing agent and thus determine the percentage yield, melting point and obtain a TLC plate for the product. INTRODUCTION Sodium borohydride is a mild reducing agent that is highly helpful for carrying out organic reduction reactions. Aldehydes and ketones can be converted into primary alcohols and secondary alcohols, respectively, using this method. Because of how mild it is, it reacts with alcohols and aqueous alkaline solutions extremely slowly. As a result, it is convenient to do the reduction with sodium borohydride in aqueous alkaline solutions or utilizing alcohols as the solvent. In contrast, anhydrous diethyl ether is the sole solvent that may be used with the much stronger reducing agent lithium aluminum hydride (Lecher, 2003). Another feature of sodium borohydride's weak reducing power is that it only reduces aldehydes and ketones, not carboxylic acids or esters, whereas lithium aluminum hydride's significantly stronger reducing power allows it to reduce aldehydes, ketones, carboxylic acids, and esters. An aromatic molecule with a pleasant scent called vanillin (4-hydroxy-3-methoxybenzaldehyde) is created when an enzyme breaks down a glycoside during the curing of the vanilla bean. The best vanilla is made from natural vanilla, while synthetic vanillin is significantly less expensive and is used much more frequently as a flavoring ingredient in culinary and scent preparation. A promising renewable starting material for the synthesis of physiologically active compounds and flavoring components is vanillyl alcohol, which is produced when vanillin is reduced, (Liberate, 2020). In this experiment, vanillyl alcohol will be created by reducing vanillin with a sodium borohydride. TLC analysis will be used to monitor the reaction, and melting point analysis and HPLC will be used to assess the product's purity. 1H-NMR and IR spectroscopy will be used to characterize the reactants and products.

RESULTS AND ANALYSIS

Reaction equation Mass(g) Molar mass (gmol-1) Moles Vanillin 0.50 152.15 0. Vanillyl alcohol 0.54 154.165 0. Sodium borohydride 0.26 37.83 0. According to the reaction equation, 4 moles of vanillin produces 4 moles of vanillyl alcohol. Therefore; n (Vanillyl alcohol) = n (Vanillin) mass( Vanyllyl alcohol theorectical yield) = n * MM = 0.00687 mol * 152.15gmol-1^ = 1.05 g IR SPECTRUM ANALYSIS FOR VANILLYL ALCOHOL Frequency(cm-1) Vibration type Strength Shape Assignment 3330.12 Stretch Strong Sharp OH 1637.40 Stretch Strong Sharp C - O 2162.15 Stretch Weak Broad =C-H 1350.83 Stretch Weak Sharp C=C IR SPECTRUM ANALYSIS FOR VANILLIN Frequency(cm-1) Vibration type Strength Shape Assignment 2945.52 Stretch Strong Sharp OH 1463.74 Stretch Strong Sharp C - O 1661.60 Stretch Strong Sharp C = O 3157.25 Stretch Weak Broad =C-H 1150.94 Stretch Weak Sharp C=C

DISCUSSION

The experimental melting point range was determined to be between 99.1 °C and 103.8 °C. The literature value for vanillyl alcohol's melting point, according to McMurry (2008), is in the region of 113 to 118 °C. This indicates that the experimental value is outside of the literature value range, and it is disregarded because it indicates that the generated product is impure. The percentage was found to be 51.42 % which is low hence this implies that errors might have occurred during the experiment. The TLC plate was used to check the progress of the reaction. It is probable that not all of the vanillin used as starting reagents was converted to vanillyl alcohol. This appears to be the case because the melting point range observed for vanillyl alcohol was 7- 9° C less than the values obtained from primary literature. This is a direct indicator of impurity in the sample NaBH 4 ionizes in a protic solvent (such as water or alcohol) to generate Na+^ and -BH 4. The carbonyl interacts with the negatively charged borohydride complex, BH 4.

REFERENCES

1. L. (2020, November 9). What is vanillin and where does it come from? - Liberate- project.eu. Liberate-project.eu.
2. McMurry, John. (2008). Organic Chemistry, 7th ed. Belmont: Thomson/Brooks/Cole.
3. Lecher, C. S. (2007) Sodium Borohydride Reduction of Vanillin: A Low Solvent Synthesis of Vanillyl Alcohol, Chemistry, Marion College.
4. NaBH4 Reduction of Vanillin. (n.d.). studylib.net. https://studylib.net/doc/8754044/nabh4-reduction-of-vanillin