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Unformatted text preview: leum ether to rinse residual white solid
from the tip of the column into your collection flask.
When all of the white solid has eluted from the
column, change the collection flask to another small
clean beaker. Allow about 5 mL of petroleum ether to
elute from the column (stop if the yellow band starts to
elute from the column), and then change the eluent to
dichloromethane. Watch the progress of the yellow
band as it will proceed more quickly down the column.
When the yellow band just reaches the bottom of the
column bed, rinse any solid from the tip of the column,
then change the collection flask to a third clean small
beaker. Continue eluting with dichloromethane until all
of the yellow band has been removed from the column
(usually ~10 mL CH2Cl2 will be required).
Analysis and Isolation. Before evaporation of the
solvents, perform TLC analysis of the column fractions,
using 15% dichloromethane in petroleum ether as the
eluent (Remember, be as accurate as possible and
prepare this solution <10 min before you use it), and the
following sample loading on the TLC plate:
Lane 1: Fraction 1
Lane 2: Fraction 2
Lane 3: Fraction 3
Lane 4: Original mixture (dilute 1 drop in 2 mL
before depositing on the TLC plate)
Isolate the fluorene and 9-fluorenone by evaporating
the solvent using the steam cone (do not use a hot plate,
as the solvent is highly flammable). When the fluorene
and 9-fluorenone are completely dry, determine the
melting points and weight of each compound.
Submit your TLC plate and samples to your section
instructor. Label samples with (1) your full name,
(2) section #, (3) date, (4) compound name.
Laboratory Report. You will write a laboratory report
for this experiment. 2...
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