Organic Chemistry I Lab
CHEM 2211L (Fall 2007)
School of Science & Technology
Georgia Gwinnett College
Experiment C. Acid-Base Extraction: Benzoic Acid, 4-Nitroaniline,
Naphthalene
______________________________________________________
1. EXPERIMENTAL OBJECTIVES:
a. Use extraction techniques to isolate an acid, base, and neutral compound.
b. Characterize and analyze products.
c. Present, analyze, and discuss results in a written report.
2. SPECIAL INSTRUCTIONS:
a. Complete the pre-lab outline (below) and prepare your lab notebook before coming to lab.
b. Before you will be allowed to begin the experiment, you must have completed lab report
sections up to procedures as described in your Instructions for Students in Organic Chemistry (ISOC).
All procedures, data, and observations must be recorded directly into the laboratory notebook as part of
the report.
c. Chemicals and solvents:
(1) Benzoic Acid, [65-85-0]
(2) naphthalene, [91-20-3]
(3) 4-nitroaniline, [100-01-6]
(4) dichloromethane, [75-09-2]
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Organic Chemistry I Lab
CHEM 2211L (Fall 2007)
School of Science & Technology
Georgia Gwinnett College
3. PRE-LAB OUTLINE:
1. The following acid-base reactions will be employed and exploited in this experiment. Complete the following table by recording
the solubility of the given compound in both water and diethyl ether (based on the data you gather for your UToRP). Then, draw the
structure of the product of the reaction (in some cases, there will be no net reaction) and predict the solubility of the product in water
and ether [indicate your prediction as either s (soluble) or i (insoluble)]. Remember the three most important words in organic
chemistry: Like dissolves like (polar solvents will dissolve polar and ionic compounds).
Rxn
Compound
Solubility
in H2O
Solubility
in Et2O
Reactant/
Reagent
Product
Solubility
in H2O
Solubility
in Et2O
O
a.
C
i
s
HCl(aq)
i
s
HCl(aq)
no rxn
-----
----
OH
b.
H2N
NO2
-
Cl+H3N
c.
HCl(aq)
O
d.
NaOH(aq)
C
OH
e.
H2N
NO2
NaOH(aq)
f
NaOH(aq)
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NO2
s
i
Organic Chemistry I Lab
CHEM 2211L (Fall 2007)
.
School of Science & Technology
Georgia Gwinnett College
Compound
Solubility
in H2O
Solubility
in Et2O
Reactant/
Reagent
Product
O
g.
HCl(aq)
C
-
O Na
+
h
O2N
NH3Cl
HCl(aq)
same
as c.
HCl(aq)
O
i.
NaOH(aq)
C
-
O Na
+
j.
O2N
NH3Cl
NaOH(aq)
same
as f.
NaOH(aq)
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Solubility
in H2O
Solubility
in Et2O
Organic Chemistry I Lab
CHEM 2211L (Fall 2007)
School of Science & Technology
Georgia Gwinnett College
2. As part of the experiment, you will add NaOH or HCl to the solution containing these three compounds and ether. Based on your
input above, in which phase (organic or aqueous) will each component (to include solvents and spectators) of the solution be found for
the following additions? Note: these are not necessarily the actual additions you will perform. You may use whatever abbreviations
you choose, as long as you provide a key to them (e.g., CO2H for benzoic acid, etc.) and show the part of the molecule or ion which
has undergone a reaction.
a.
O
O
C
C
OH
H2N
NO2
OH
H2N
NO2
HCl(aq)
aqueous phase:
Draft
NaOH(aq)
organic phase:
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aqueous phase:
2/12/16
organic phase:
Organic Chemistry I Lab
CHEM 2211L (Fall 2007)
School of Science & Technology
Georgia Gwinnett College
b.
O
O
C
C
-
O Na
-
Cl+H3N
+
O-Na +
-
NO2
Cl+H3N
NO2
HCl(aq)
aqueous phase:
Draft
NaOH(aq)
organic phase:
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aqueous phase:
2/12/16
organic phase:
Organic Chemistry I Lab
CHEM 2211L (Fall 2007)
School of Science & Technology
Georgia Gwinnett College
4. PROCEDURES:
Apparatus
1. Begin cooling two small test tubes of distilled water in an ice bath for later use in rinsing products
in the Hirsch funnel.
2. You will start out using your centrifuge tube with cap rather than the conical vial. The three
component mixture and dichloromethane all go into the centrifuge tube initially.
3. Use a Hirsch funnel connected to the sink aspirator for vacuum filtration.
4. Use the sand bath in your hood for flameless heating, with aspirator if needed.
Dissolution
5. Liquid reagents throughout the lab are approximate so you may use the calibrated plastic,
disposable pipets.
6. Use 4 mL of dichloromethane rather than 3 mL noted in your text.
7. Cap your centrifuge tube and then use the vortex mixer to mix. It takes a while, but all of the
solid should go into solution.
Extraction
8. Use three extractions with 6 M HCl rather than the two extractions noted in your text.
9. Use two extractions with 3 M NaOH rather than the one extraction noted in your text.
10. At the end of the extraction, leave your organic layer in the centrifuge tube rather than
transferring it to a clean test tube.
Precipitating and Drying
11. Rather than the drying technique described in the text, dry the "Neutral Compound" by running
it through a Pasteur filter pipet filled with anhydrous sodium sulfate and into your 5 mL conical vial.
After drying, evaporate the solvent in the hood in the warm sand bath and aspirator as needed. Do
not heat too vigorously or your product will “bump” out of the vial and into your sand. If all of the
solvent does not come off during the first lab period, mark your vial and store it uncapped until the
second lab period.
Draft
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Organic Chemistry I Lab
CHEM 2211L (Fall 2007)
School of Science & Technology
Georgia Gwinnett College
12. Use small pieces of pH paper on a glass evaporating dish (“watch glass”)to test pH of your HCl
and NaOH extract solutions as you neutralize them with the 6 M NaOH and 6 M HCl. You may
need to use your spatula to stir the mixture during neutralization.
13. Skip the procedure of ... "Rinse each solid back into its respective test tube..." and instead
vacuum filter the contents of the test tubes using the Hirsch funnel. Make sure you wet the filter
paper and have good vacuum before dumping your test tube contents into the funnel. Be careful not
to overflow the filter paper by pouring too much liquid into the funnel at a time. Wash each solid
precipitate as you collect it in the Hirsch funnel with several 1.0 mL aliquots of cold distilled water
(# 1 above). You may need to add an additional 1mL of water to the test tube to recover more
product if some remains behind after the first transfer. Then transfer each washed solid from the
filter paper to a labeled, pre-weighed container. You will store these solid products uncapped until
the second lab period.
14. You will not recrystallize your products.
15. At this point you have isolated your three solid compounds. Allow them to air dry, uncapped
until you return for the next lab session.
Analysis
16. Determine mass % and mole ratio of each of the three components in the original mixture.
17. Conduct melting point analysis of benzoic acid, naphthalene and 4-nitroaniline.
18. Determine product recovery (%).
Draft
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