Synthesis of Biodiesel and Soap Experiment 10 Post-Lab Notes

Introduction

Esterification: Reaction of an alcohol with a carboxylic acid to produce water and an ester.
Transesterification: Exchange of the alkoxy group, converting one ester to another. The reaction is catalyzed during biodiesel production from vegetable oil.
Saponification: Mechanism where an alkali converts oils into soap and glycerol.
Transesterification Example: Triglycerides react with methanol to create biodiesel (Ashenhurst, 2022).
Saponification Example: Sodium hydroxide reacts with fats in an aqueous solution to produce solid soap (Banks, 2013).

Synthesis Mechanism of Biodiesel

Details of the Synthesis Mechanism of Biodiesel are expected here

Side Reaction of Biodiesel

Details of the Side Reaction of Biodiesel are expected here

Synthesis Mechanism of Soap

Details of the Synthesis Mechanism of Soap are expected here

Side reaction of Soap

Details of the Side Reaction of Soap are expected here

Experimental Section: Procedure – Flowchart

Part A: Synthesis of Biodiesel from Vegetable Oil

Conical flask (250-mL) + stir bar + $300mg$ KOH + $8.5mL$ Methanol + cover flask with parafilm + stir until dissolved.
Heated $32mL$ at 60 ºC + cover with parafilm + stir at 60ºC for 1 hour.
Separatory funnel + separate 20-30 min + two layers (bottom & top).
Glycerol (bottom layer) and biodiesel (top layer).
Once the top layer (biodiesel) is confirmed, drain the remaining layer.
Weigh biodiesel and calculate % yield.
$3mL$ biodiesel + do 27/3 MeOH test.
Pipette $3mL$ top layer + pour to cylinder + mix to see one homogenous solution for a positive test.

Part B: Synthesis of Soap from Vegetable Oil

250-mL Beaker + large stir bar + $50g$ coconut oil + heat to liquefy at 100ºC.
Add 30% w/w NaOH solution (basic solution).
Heat & stir at 90-100ºC for 1 hour.
Transfer molten soap to watch glass and let it cool.
Shape & compress semi-solid soap to form a soap bar.
Compare cooling soap (15 min).
Dry soap for 2 weeks; coconut oil must be superfatted to avoid drying the skin.

Characterization of Soap

$10mL$ graduated cylinder + add a small piece of soap + $5mL$ water, shake to see what happens (foaming?).
Test pH with litmus paper to check reaction completion.
Add $CaCl_2$ to dry the water and see what happens (foaming diminished?) to confirm completion of testing.

List of Chemicals Used:

Hydrogen Peroxide: $H2O2$ , Molecular weight: $34.015 g/mol$ , Melting point: $-0.43 ºC$ , Boiling point: $150.2 ºC$ , IUPAC name: Hydrogen peroxide. Hazards: Causes severe skin burns and eye damage, harmful if swallowed, and may cause respiratory irritation.
Hydrogen Bromide: $HBr$ , Molecular weight: $80.91 g/mol$ , Melting point: $-87ºC$ , Boiling point: $-67ºC$ , IUPAC name: bromane. Hazards: Causes severe skin burns and eye damage, causes damage to organs, contains gas pressure; may explode if heated, may cause respiratory irritation, toxic if inhaled.
Ethanol: $C2H6O$ , Molecular weight: $46.07 g/mol$ , Melting point: $-114.1 ºC$ , Boiling point: $78.2ºC$ , IUPAC name: ethanol. Hazards: Causes serious eye & skin irritation, flammable liquid & vapor, may cause drowsiness or dizziness.
Ethyl Acetate: $C4H8O_2$ , Molecular weight: $88.11 g/mol$ , Melting point: $-83.6 ºC$ , Boiling point: $77.1ºC$ , IUPAC name: Ethyl acetate. Hazards: Flammable liquid & vapor, causes dizziness or drowsiness, causes serious eye irritation.
Sodium Hydrogen Carbonate: $NaHCO_3$ , Molecular weight: $84.007 g/mol$ , Melting point: $50ºC$ , Boiling point: $851ºC$ , IUPAC name: Sodium; hydrogen carbonate. Hazards: Causes eye & respiratory irritation, causes mild skin irritation, harmful if swallowed.
Stilbene: $C{14}H{12}$ , Molecular weight: $180.25 g/mol$ , Melting point: $124º C$ , Boiling point: $306-307ºC$ , IUPAC name: ∈-Stilbene. Hazards: Causes serious eye irritation, harmful if swallowed, toxic to aquatic life.
Water: $H_2O$ , Molecular weight: $18.015 g/mol$ , Melting point: $0 ºC$ , Boiling point: $100 ºC$ , IUPAC name: Oxidane. Hazards: None.

Results

Mass of Biodiesel: $20.78g$
Color & Appearance of Biodiesel: Light yellow
Mass of prepared soap: $50.28g$
Odor of prepared soap: fresh like cleaning supplies
Appearance of prepared soap: White

Discussion

The biodiesel preparation involved transesterification, where triglycerides reacted with alcohol and a catalyst.
This reaction promotes energy sustainability by producing a clean fuel alternative.
The soap preparation involved saponification, reacting triglycerides with alkali to form soap.
This reaction utilizes natural oils for personal hygiene, reducing hazards and promoting environmental sustainability.

Conclusion

The experiment successfully synthesized soap with a total mass of $50.28g$ .
The separatory funnel clearly showed two layers of organic and aqueous substances.
These techniques can decrease waste and contribute to skincare product manufacturing.
The experiment achieved its goals by successfully demonstrating both syntheses without excessive waste.

References

Weldegirma, S. (2024) Experimental Organic Chemistry: Laboratory Manual for CHM 2210L and CHM2211L
Banks, R. (2013, October 2). Esterification. Chemistry LibreTexts. https://chem.libretexts.org/Bookshelves/OrganicChemistry/SupplementalModules(Organic Chemistry)/Esters/SynthesisofEsters/Esterification
Ashenhurst, J. (2022, November 10). Transesterification. Master Organic Chemistry. https://www.masterorganicchemistry.com/2022/11/10/transesterification/