Ethyl Acetate Lab Report

In this experiment, the following chemicals were used; benzocaine, benzoic acid, ethyl acetate, sodium hydroxide, acetone, sodium benzoate, hydrogen chloride, methylene chloride, and glacial acetic acid.

In this experiment, acetone was used to make sure that the glassware being used was clean and dry and there was not any residue of leftover chemicals. Benzocaine, a local anesthetic, and Benzoic acid, a mild irritant, are the two products that were to be isolated and cleaned up using various techniques in this experiment. Ethyl Acetate was mixed with the unknown benzoic acid sample and acted as the solvent while Sodium Hydroxide acted as the aqueous solution in the seperatory funnel technique and was to be drained off leaving only the organic

phase behind.
Sodium Benzoate acted as the drying reagent which was dissolved in the aqueous layer from the sepeartory funnel. Hydrogen Chloride was added to the sodium benzoate and aqueous layer mixture to lower the pH of the solution to a pH of 1
Methylene Chloride was used to turn the benzocaine sample which was in a solid phase into a liquid phase so that the sample could be transferred onto a salt plate for IR spectrum reading
Glacial acetic acid – used to complete TLC. Placed in beaker with water and the TLC plate placed in the solution once spotted with solutions to develop the TLC plate until the solvent plate was near the top of the slide.
Equipment used:
Separatory funnel:
A separatory funnel (Figure 2) was used for the extraction of the benzoic acid sample by using two solvents that do not mix together.

The solvents used in this experiment were sodium hydroxide as the aqueous layer and the ethyl acetate and unknown benzocaine as the organic phase. These phases are separated with an emulsion line which is a distinct line that shows where the aqueous and organic layers meet but do not mix. This method of separation relies on portioning the preferential dissolution of a compound into one solvent over another (2).

Figure 2 also shows that when a solvent is used that is lighter than water, density < 1, the organic phase will be on the top in the separatory funnel, while solvents denser than water, density > 1, will sink to the bottom of the funnel (2). The success of the separatory funnel technique allowed for Thin Layer Chromatography (TLC) and Infrared Spectroscopy (IR) analysis.

A Digi-Melt apparatus was used to measure the melting points of the benzoic acid and benzocaine samples which were extracted using the separatory funnel. Based on the observed melting point ranges for each sample, purity could be determined. A tight melting point range that is very close to the reference melting point is considered to be very pure. This is when the range is ~2 ̊C, but is not within 5 ̊C of the reference melting point range

(3).
Thin Layer Chromatography (TLC):
TLC was developed in a mixture of glacial acetic acid and spotted with the extracted samples of benzocaine and benzoic acid and the reference of each sample, benzoic acid and benzocaine. Once the TLC plate was spotted and developed, the plate was placed under a UV Light and the spots of the samples examined. “The spots can be characterized by their Rf value (retention factor), which is defined as the distance traveled from the origin divided by the distance traveled by the mobile phase” (4).

Infrared (IR) Spectroscopy:
Infrared Spectroscopy was used as a source of revealing stretches and bending modes within the molecule, and reactions can be followed by observing the disappearance of one bond and the appearance of another. IR is used to provide proof that the desired transformation has occurred.