Synthesis of Bromotriphenylamine with TCNE
Catherine Joson
Abstract
The crystallizing of Bromotriphenylamine with TCNE is studied within a variety of a
DCM:Hexane solvents. With the theory of crystallization, extraction, column chromatography
and the method of using the melting point apparatus and TLC, the long and arduous twenty-one
(21) day experiment was successfully completed.
Introduction
The transfer of knowledge from textbook to laboratory work is imperative in any science
discipline. This skill is exemplified within this specific reaction through the combination of the
many techniques discussed within our textbooks. There have been various instances when
electrophilic aromatic substitution reactions been studied. This experiment delivers the quality
of many techniques with a reaction of TCNE, tetracyanoethylene, and Bromotriphenylamine in a
1:1.2 ratio that has never been studied. Within this experiment, the intended end product and
mechanism is all hypothetical. One can only base the reaction that is going to take place from
previous knowledge of electrophilic aromatic substitution.
Electrophilic aromatic substitution is when an electrophile reacts with an aromatic ring and
substitutes for one of the hydrogens. This is a test of aromaticity. Common electrophilic
aromatic substitution includes: aromatic nitration, aromatic halogenation, aromatic sulfonation,
and lastly, acylation.
However, this experiment has never been recorded and/or studied. Thus, it is a very efficient
way to test our knowledge and skills that we’ve learned and transcend this moment, not as
undergraduate students, but as scientists. This is the meticulous lives of real scientists. This is
the true test of fate.
Materials


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20 mL of DMF
0.5g of Bromotriphenylamine
(Aldrich)
.2369g of TCNE (Acros ’03)
10mL Distilled H₂O





50.0 mL DCM (CH₂Cl₂)
Appropriate amount of MgSO₄
Round bottom flask
Extraction funnel
Stirring bar
Synthesis of Bromotriphenylamine with TCNE
Catherine Joson
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TLC paper
Micropipets
Column Chromatography
Silica Gel 150 A
Safety
Please be advised the following:
Bromotriphenylamine is:


(harmful)
harmful if swallowed
irritating to eyes, respiratory system, and skin
In case of contact with eyes, rinse immediately with plenty of water and seek medical
advice.
Wear suitable protective clothing.
Tetracyanoethylene is:


(toxic)
Toxic by inhalation, contact with skin
Very toxic if swallowed.
After contact with skin, wash immediately with plenty of soap-suds.
Wear suitable protective clothing.
In case of accident or if you feel unwell, seek medical advice immediately (show the
label whenever possible).
DMF is:



(toxic)
Harmful by inhalation or if swallowed.
Irritating to eyes.
May cause harm to unborn child.
In case of accident or if you feel unwell, seek medical advice immediately (show the
label whenever possible.)
Avoid exposure – obtain special instructions before use.
Dichloromethane is:
(harmful)
Synthesis of Bromotriphenylamine with TCNE
Catherine Joson

Limited evidence of a carcinogenic effect.
Do NOT breathe vapor.
Avoid contact with skin and eyes.
In case of contact with eyes, rinse immediately with plenty of water and seek medical
advice.
Wear suitable protective clothing.
Procedure
1. Reaction of Bromotriphenylamine with TCNE
a. Collect 0.5g of Bromotriphenylamine into a round bottom flask.
b. Add 0.2369g of TCNE.
c. Add 20mL of DMF.
d. Stir using oval stirring bar at room temperature.
e. Leave overnight for 48 hours at room temperature.
2. Extraction of Mixture
a. Extract reaction mixture with 100.0 mL of H2O and 50.0 mL of CH2Cl2. (3
TIMES)
b. CAREFULLY mix the solution within the funnel. (Enormous pressure build-up
within funnel.)
c. Test which layer is organic or aqueous.
d. Combine Organic Layers
e. Add MgSO₄ to remove water.
f. Gravity filtrate MgSO₄ from CH2Cl2.
g. Extract aqueous solution from extraction funnel. (If you haven’t done so yet.)
h. Evaporate DCM – collect solid
3. TLC of Mixture
a. Find best solvent for purifying your compound.
b. Dispense six (6) 50 mL of DCM and Hexane into the TLC glassware according to
the following:
i. Start by using 100% DCM and 0% Hexane.
ii. Decrease the concentration gradient of DCM in increments of 20%.
iii. Increase the concentration gradient of Hexane in increments of 20%.
iv. Vary composition until you obtain good separation.
4. Column Chromatography
a. Prepare solvent according to TLC results.
b. Collect fractions (each containing at least 10 mL of product)
c. Combine identical fractions.
d. Cover fractions with aluminum foil and let sit overnight for 48 hours.
e. Get pure solids
Synthesis of Bromotriphenylamine with TCNE
Catherine Joson
Results
Product was isolated as mauve-shaded crystalline weighing 0.291 grams. However, upon
extracting the crystals from the E. Flask, the crystalline broke and the majority of it turned into
powder. The percent yield of the total end product resulted as 56.9%.
Melting Point:
Expected MP Range: 108° - 112°C
Actual MP:
103° - 106°C
¹³C NMR:
¹H NMR:
Synthesis of Bromotriphenylamine with TCNE
Catherine Joson
Discussion
The best solvent to be used within this experiment concluded to 80% DCM and 20% Hexane.
When dealing with hexane, one must remember that the evaporation of hexane is much higher
than DCM. Thus, the TLC (thin layer chromatography) glassware must be closed as much as
possible. Because of its simplicity and speed, TLC was used to quantitatively analyze the
reaction products and identify the compounds present in the given substance. Refer to Figure 1
for a quick mechanism of TLC.
Figure 1: Typical Thin Layer Chromatography
Tip:
Make sure the equipment is FULLY washed and rid of soap. When
measuring the correct amount of distilled H₂O with a graduated
cylinder and pouring it into the extraction funnel, the reaction turned
pink—as oppose to a dark purple. The reaction was fine tuned with
the addition of acid and acetonitrile to balance aqueous solution.
Thus, making it “comfortable” in H₂O.
In conclusion, the results of this experiment proved that the what you learn in the textbook is
used within the “everyday” science life.