Organic Chemistry
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111.pdf
1. State true or false a) While visualizing the chromatogram, you can directly look at the UV light. b) The Iodine jars should not be removed from the hoods. c) Since the unknown solutions used in this experiment are analgesic drug mixtures, it is
not a big concern if some solution spills on my hands.
2.
3. List three factors on which the retardation factor (Rf) of a compound depends on.
• • •
4. What is the purpose of using a piece of filter paper in the TLC developing chamber during this experiment?
F T
F
TLC separates compounds based on their ……Polarity…………
polarity of the compound
polarity of the solvent
polarity of the absorbent
To keep the atmosphere within the glass block saturated with solvent vapors at all times
5. In experiment 3A, you will compare the Rf values of o-hydroxy-acetophenone and p- hydroxy-acetophenone. Which compound do you think will have the greater Rf value?Justify your answer.
O
OH
O
OH
o-hydroxy- acetophenone
p-hydroxy- acetophenone
6. Arrange the following compounds in the increasing order of Rf.
a)
b) Br
c) COOH
d)
O
O
o hydroxy acetophenone have higher Rf balue
O- hydroxy acetophenone has intramolecular H bonding, which
makes it less polar
B,D,C,A
7. Write the equation for calculating Rf. Calculate the Rf values for the two spots A and B.
1
2
3
4
5
A B
8. Where should you properly dispose of a) Used TLC capillaries? : b) Used TLC plates? :
mason jar
keeper
a, 2/5=0.4
b, 3.5/5=0.7
9. Suppose you performed acetylation of ferrocene (see reaction scheme). You monitored the reaction using TLC and made the following observations. [Note: Acetyl group (Ac) is polar]
Reaction Scheme:
Fe Fe Fe Ac Ac
Ac
O
O
O
H3PO4
Major Product
Unwanted Side Prpduct
+
R O
Ac =
Observations:
At t = 0 min
At t = 15 min
At t = 30 min
What is the optimum time to stop the reaction and why?
The optimum time to stop the reaction is t=15 min. according above, we know t=30min had 2 extra
products, and t=15min only had one product. therefore, t=15 min is optimum time to stop.
