Experiment 5: Extraction

Joseph Personelli

Lab Partner: Benjamin Lowry

Organic Chemistry 1

Dr. Joseph Kappel

LA: Stacey Mendigutia

3/10/15

Abstract:

The purpose of this experiment was to evaluate the effectiveness of an

extraction technique involving acidic, basic, and neutral compounds. The products

that were sought were 9-fluorenone, the neutral component, benzoic acid, the

acidic component, and ethyl 4-aminobenzoate, the basic component. The

hypothesis was accepted but with reservations. The melting points determined

backed the hypothesis but the percent recoveries of 18.8% for benzoic acid and

71.53% for ethyl 4-aminobenzoate indicated that there was an error during the

experiment.

Introduction

The purpose of this experiment was to utilize, observe, and determine the

effectiveness of an extraction technique for use on acidic, basic, and neutral compounds.

Extraction is a laboratory technique that is utilized to isolate a product or to purify a

product from a compound.

The extraction method that was utilized throughout this experiment was liquid-

liquid extraction. According to UCDavis “liquid-liquid extraction is a method by which a

compound is pulled from solvent A to solvent B where solvents A and B are not

miscible.”2 This was accomplished when the acids and bases, hydrochloric acid and

sodium hydroxide, were brought together into a prepared mixture of already acids and

bases. These aforementioned acids and bases were added to have the already present

acids and bases react for easy separation.

After extraction the melting point and the percent recovery were then calculated

to ensure that the experiment was properly performed. The melting point refers to the

temperature in which the recrystallized product changes from a solid to a liquid. This

helps to determine the purity of the product. The percent recovery determines how much

of the recrystallized product forms divided by the initial amount added.

The acid that was extracted was benzoic acid. The basic component of this

experiment was the ethyl 4-aminobenzoate. Finally, the neutral component of this

experiment was the 9-fluorenone.

It was hypothesized that a liquid-liquid extraction technique could be utilized to

extract acids, bases, and neutral compounds from a mixture.

Benzoic Acid Ethyl 4-aminobenzoate 9-Fluorenone

Materials and Methods:

For information on the method of extraction, please refer to Chapter 6,

Experiment 4C on pages 147-150 from the Lab manual of Microscale Organic

Laboratory with Multistep and Multiscale Syntheses by Dana W. Mayo, Ronald M. Pike,

and David C. Forbes. No alterations were made do this procedure.

Results:

Table 1: Initial measurements of added compounds

Mass of 9-Fluorenone (g) 0.053

Mass of Ethyl 4-Aminobenzoate (g) 0.052

Mass of Benzoic Acid (g) 0.054

Mass of Anhydrous Salt (g) 0.3063

Table 1 shows the mass measurements of the added acid, base, neutral compound and

salt.

Table 2: Extracted Compounds

Mass of beaker and boiling stones (g) 8.476

Mass of filter paper (1) (g) 0.1039

Mass of filter paper (1) and Ethyl 4-

Aminobenzoate (g)

0.1411

Mass of filter paper (2) (g) 0.1040

Mass of filter paper (2) and benzoic acid

(g)

0.1142

Table 2 shows the measurements of extracted componenets

Table 3: Calculations and Recovery Mass (g) Percent Recovery (%)

Ethyl 4-Aminobenzoate 0.0372 71.53

Benzoic Acid 0.0102 18.8

Table 3 shows the calculated masses of the acidic and basic components as well as the

percent recovery of each.

Table 4: Melting points of extracted compounds

Benzoic Acid (oC) 110

Ethyl 4-Aminobenzoate (oC) 87

9-Fluorenone (oC) 64

Table 4 shows the melting points of the extracted compounds

Calculations:

Mass of Ethyl 4-Aminobenzoate: mass of filter one and compound – initial mass of

filter paper = 0.1411 – 0.1039 = 0.0372

Mass of Benzoic Acid: mass of filter paper two and compound – initial mass of filter

paper = 0.1142 – 0.1040 = 0.0102

Percent Recovery of Ethyl 4-Aminobenzoate: (final mass / initial mass) * 100 =

(0.372 / 0.052)* 100 = 71.53 %

Discussion:

The purpose of this experiment was to utilize, observe, and determine the

effectiveness of an extraction technique for use on acidic, basic, and neutral compounds.

One of the techniques utilized during this experiment was a liquid-liquid extraction. To

determine the effectiveness the percent recoveries were calculated.

The percent recovery of the benzoic acid and the ethyl 4-aminobenzoate, as seen

in Table 3, were 18.8% and 71.53% respectfully. The percent recovery of the 9-

fluorenone was not calculated due to some errors that occurred during the lab. The initial

masses regarding the 9-fluorenone were not taken and therefore could not be utilized in

calculating the percent recovery.

The melting points of the recovered products, as seen in Table 4, were determined

and compared to the standards of the lab manual to ensure that the products extracted

were pure. According to the lab manual the melting points of benzoic acid, benzoate

product, and 9-fluorenone are 122°C, 89°C, and 84°C respectfully. The melting points of

the extracted products of benzoic acid, benzoate product, and 9-fluorenone were

determined to be 110°C, 87°C, and 64°C respectfully. After comparing the extracted

products to the standards of the lab manual it can be determined that the extraction of the

benzoate product was the most pure. The melting point of the extracted 9-fluroenone was

about 20°C cooler than the standard from the manual.

An error that occurred that could have had an influence on the results that were

calculated and recorded was that the lid was left off of the anhydrous salt bottle. The

moisture of the South Florida air could have been absorbed resulting in data that is

incorrect. To eradicate this from future experiments the lid should be replaced

immediately after the appropriate amount of anhydrous salt was taken.

Conclusion:

The hypothesis of this experiment was accepted but with reservations. It was

accepted because the percent recoveries and the melting points were able to be

determined by means of perform the extraction technique. However, the reservations

arise in the calculated percent recoveries: benzoic acid and the ethyl 4-aminobenzoate

with 18.8% and 71.53% respectfully. One suggestion to improve this experiment is to

keep the anhydrous salt closed and put away when not needed.

Questions:

6-23: The solubility of p-dibromobenzene would be greater if dissolved by acetone than

by benzene. The atoms of the element bromine have a high electronegativity resulting in

a polarity that is localized. Because p-dibromobenzene has specific polarity it will

dissolve in acetone.

6-24: The standard density of methylene chloride is 1.326 g/cm. This means the

methylene chloride will form a low layer and the ice cube will float on top of it due to the

ice cubes density ~1. Pentane has a lower density compared to the ice cube 0.626 g/cm

meaning the pentane layer will form above the ice cube. The same is true for toluene –

the layer will form above the ice cube because the ice cube is more dense compared to

the density of toluene, 0.867 g/cm. Like the two aforementioned solvents, diethyl ether

will also form a layer above the ice cube because the density of the diethyl ether is 0.713

g/cm.

References

1 Mayo, D. W., Pike, R. M., & Forbes, D. C. (2011). Microscale Organic Laboratory

with Multistep and Multiscale Synthesis. Hoboken: John Wiley & Sons, Inc.

2 Liquid-Liquid Extraction. (n.d.). Retrieved April 12, 2015.

<http://chemwiki.ucdavis.edu/Reference/Lab_Techniques/Liquid-

Liquid_Extraction>