Chemistry Question

Name:Exp #
Date:
Lab Partner
Title:
1. Abstract and Purpose: (2 point).
2. Balanced equation: (2 point)
There are several free structure drawing programs available e.g. acdlabs.com. If you
don’t have a drawing program, hand draw the structures.
3. Reagent Table (Add more rows when needed) (3 points)
Name
M.W.
(g/mol)
Density*
(g/mL)
M.P.*
(°C)
B.P.*
(°C)
Amount
(grams
or mL)
Moles
Hazards/Precautions
N.B. For solvents (like methanol) or drying agents (e.g. sodium sulfate), you don’t
need to calculate the moles.
* Report only when applicable
4. Calculations: Shown each calculation for moles of reagents, limiting reagent,
theoretical yield and percent yield. (4 points)
Calculating moles of reagents:
Name:
Exp #
Date:
Lab Partner
Determining limiting reagent:
The limiting reagent is
Calculating theoretical yield:
The theoretical yield is
The actual yield is
Calculating Percent yield:
Reaction percent yield is
5. Procedure, Observations and Data
Procedure (4 point)
Observations and Lab Data (4 point)
A summary of the procedure done with bullet points)
Report all observations and all data that you collect in the
(2 points)
lab here
6. Conclusions and discussions (4 points)
7. References: (1 point)
Name:
Lab Partner
Exp #
Date:
8. Image of your lab notebook. (3 point)
I reserve the right to modify points on this template at any time.
Organic Chemistry I Laboratory
Experiment 5 and 6:
Thin-layer Chromatography
&
Column Chromatography
Thin-layer Chromatography
•Thin layer chromatography, or TLC, is a method for
analyzing mixtures by separating the compounds in the
mixture.
•TLC can be used to help determine the number of
components in a mixture, the identity of compounds, and
the purity of a compound. By observing the appearance of
a product or the disappearance of a reactant, it can also be
used to monitor the progress of a reaction.
•TLC is a sensitive technique – microgram (0.000001 g)
quantities can be analyzed by TLC – and it takes little time
for an analysis (about 5-10 minutes).
Thin-layer Chromatography
•As stationary phase, a special finely ground matrix (silica gel,
alumina, or similar material) is coated on a glass plate, a metal or a
plastic film as a thin layer (~0.25 mm). In addition a binder like
gypsum is mixed into the stationary phase to make it stick better to
the slide. In many cases, a fluorescent powder is mixed into the
stationary phase to simplify the visualization later on (e.g. bright
green when you expose it to 254 nm UV light).
Column Chromatography
• Column chromatography is one of the most important methods of
separating (and purifying) a single chemical compound from a
mixture. Chromatography is able to separate substances based on
differential adsorption of compounds to the adsorbent;
compounds move through the column at different rates, allowing
them to be separated into fractions.
• Column chromatography works on the same principle of TLC
except that the sample solution flows down a column of silica gel
or alumina filled with solvent.
• Normally, a separation will begin by using nonpolar or low polarity
solvent, allowing the compounds to adsorb to the stationary
phase, then SLOWLY switching the polarity of the solvent to desorb
the compounds and allow them to travel with the mobile phase.
Column Chromatography
Objectives of Lab 4
•
•
•
Set up the NaBH4 reduction reaction of fluorenone to fluorenol in MeOH
Monitor the reduction of fluorenone to fluorenol using thin-layer chromatography.
Get familiarized with the TLC techniques and know how to calculate Rf value.
Calculating Rf Value in TLC
•
•
The components, visible as separated spots, are identified by comparing the
distances they have traveled with those of the known reference materials.
Measure the distance of the start line to the solvent front (=d). Then measure
the distance of center of the spot to the start line (=a). Divide the distance the
solvent moved by the distance the individual spot moved. The resulting ratio is
called Rf-value.
Fluorenone vs. Fluorenol
Spotting, Development, and Visualization of TLC
• Spotting consists of using a micro pipet to transfer a small amount of this dilute
solution to one end of a TLC plate. The spotting solvent quickly evaporates and
leaves behind a small spot of the material.
• Development consists of placing the bottom of the TLC plate into a shallow pool
of a development solvent, which then travels up the plate by capillary action.
• Different components in the original spot, having different polarities, will move
different distances from the original spot location and show up as separate spots.
• When the solvent has traveled almost to the top of the plate, the plate is removed,
the solvent front marked with a pencil, and the solvent allowed to evaporate.
• Visualization method:
• The silica gel on the TLC plate is impregnated with a fluorescent material that glows
under ultraviolet (UV) light. A spot will interfere with the fluorescence and appear as
a dark spot on a glowing background. While under the UV light, the spots can be
outlined with a pencil to mark their locations.
• A second method of visualization is accomplished by placing the plate into iodine
vapors for a few minutes. Most organic compounds will form a dark-colored complex
with iodine.
Materials
• 6 Premade TLC plates
• Fluorenone, MeOH, NaBH4, fluorenol, water, CH2Cl2
• 50 mL Erlenmeyer flask with a stir bar
• Micropipette
• TLC chamber
• 50 mL Erlenmeyer flask
• Buchner funnel
• Filtration flask
• M.P. tubes and apparatus.
Safety Consideration
• Wear PPE. Use Nitrile gloves especially when handling chemicals;
Handle them inside the hood. Avoid any contact with skin and direct
inhalation.
• Study the MSDSs of all chemicals before coming to the lab.
• Methanol is flammable.
• Methylene chloride is a suspected carcinogen!
• NaOH and HCl come in different concentrations; Make sure you pick
the right one!
• Wash your hands before leaving the lab.
Procedures (to be continued…)
• Accurately weigh out about 0.5 g of fluorenone in a 50 mL Erlenmeyer flask. Add
10 mL of methanol and a spin vane. Stir until dissolved.
• Prepare your TLC chamber by adding 5 mL of CH2Cl2 in it. Keep the cap closed.
• Using 6 premade TLC plates (Mark 0, 15, 30, 60, 120 and 180 seconds
respectively on the top right corner) take a pencil and draw a line with three
equally spaced marks about 5 mm from the bottom and another line about 5
mm from the top.
• Using a micro pipet to transfer a small amount of fluorenone (starting material,
yellow color) on the first spot of each plate.
• Taking another micro pipet to transfer a small amount of fluorenol (product,
colorless) on the third spot of each plate.
• Using a micropipette, spot the plate at the 0 time point with the standard.
Procedures
• Weigh out about 0.1 g NaBH4 and quickly add it to the reaction. Start Your timer.
• At each of the designated time points (15, 30, 60, 120 and 180 seconds) remove a
sample with a clean micro pipette and spot the appropriate TLC plate.
• Develop the plates in the TLC chamber using CH2Cl2 (until the solvent front reach the
top line) and record your results. Calculate Rf and take a picture of your TLC to be
attached in your report.
• After seven minutes total reaction time, add 5 mL of water and heat almost to boiling
until it turns clear.
• Cool to room temperature to induce crystallization and then put in an ice-bath to
complete the process.
• Collect the crystals using a Buchner funnel and vacuum filtration..
• Dry by pulling air through the funnel for additional 5 minutes.
• Weigh your product to report the crude yield and take a melting point of the crude
product next week.
Before you leave…
• Clean and return all glassware to your drawer.
• Clean your Hood, bench top and wash your hands
• Have your instructor sign your data sheet, which is to be attached with your lab
report
Name
Exp # 5 and 6
Date:
Lab Partner:
Title: TLC and Flash Column Chromatography
Abstract and Purpose: (2 point).
In this preparative lab experiment the reduction reaction from fluorenone to fluorenol in methanol
will be analyzed. Thin Layer Chromatography is a method of monitoring the reaction while Flash
Column Chromatography is a way to purify the mixture. TLC works by separating the compounds
in the mixture and helps determine the number of the products, identify those products, and also
aids in the purification process. TLC uses a plate that has a finely ground matrix coated with a
glass plate for stability. It uses a thin layer of an absorbent material as a stationary phase and a
solvent mixture as a mobile phase (9-fluorenol). Column Chromatography is performed by also
using a mobile phase, but in the case of Flash Chromatography it is forced through a column of the
absorbent. The stationary phase uses silica gel and a polypropylene tube filled with the material.
The mobile phase occurs by having a solvent gradient that removes the components of the mixture,
thus purifying it. The first part of the experiment uses thin-layer chromatography that tests for the
reaction from fluorenone to fluorenol at every thirty second interval; from the stationary phase to
the mobile. Once the crude product is formed, a white fluffy material, then column
chromatography is utilized to purify the crude product and separate it into fractions collected via
test tubes. Towards the end of the lab experiment students will be familiarized with assembling
TLC plates and chambers, spotting the plates, visualizing the spots under UV radiation, assembling
the column chromatography equipment, and then calculating the R(f) value of the solvent.
Name
Exp # 5 and 6
Date:
Lab Partner:
Balanced equation: (2 point)
Fluorenone
Fluorenol
3. Reagent Table (Add more rows when needed) (3 points)
Name
M.W.
(g/mol)
Dens
ity*
(g/m
L)
M.P.
*
(°C)
B.P.
*
(°C)
Amou
nt
(grams
or mL)
Moles
(mmol)
Sodium
37.83
Borohydrid
e
1.07
4
>
300
N/A
0.5
0.0052
Methanol
CH4O
32.04
0.79
1
-98
64.7
20
0.62
Hexane
C6H14
86.18
0.65
9
-95
69
15
0.174
Hazards/Precautions
Do not allow contact with water.
Do not breathe dust or mist.
Wash skin thoroughly after handling.
Toxic if swallowed. Causes severe skin
burns and eye damage. May damage
fertility or the unborn child.
Highly flammable liquid and vapour.
Toxic if swallowed, in contact with
skin or if inhaled. Causes damage to
organs. Keep away from
heat/sparks/open flames/hot surfaces.
Keep the container tightly closed. Use
only non-sparking tools. Do not
breathe in and Wash skin thoroughly
after handling.
Flammable liquids, Skin irritation,
Reproductive toxicity, Specific target
Name
Exp # 5 and 6
Date:
Lab Partner:
Fluorenone
C13H8O
180.20
N/A
80 83
342
0.5
0.0028
Fluorenol
C13H10O
182.22
N/A
N/A
N/A
N/A
Ethyl
acetate
C4H8O2
88.1
0.90
153
154
-84
76.5
77.5
15
0.170
Dichlorom
ethane
CH2Cl2
84.93
1.32
5
-97
39.8
– 40
5
0.059
organ toxicity, Aspiration hazard and
Acute and chronic aquatic hazard
Causes serious eye irritation. Toxic to
aquatic life with long lasting effects.
Wash skin thoroughly after handling.
Avoid release to the environment. Wear
eye protection/ face protection.
Not a hazardous substance or mixture
Flammable liquids, Eye irritation,
Specific target organ toxicity, single
exposure: Central nervous system.
Highly flammable liquid and vapour.
Causes serious eye irritation. May
cause drowsiness or dizziness. Avoid
breathing in and wash skin
thoroughly after handling.
Carcinogen, Target Organ Effect,
Harmful by ingestion, Irritant Target,
Causes eye irritation.
Carcinogenicity.
Harmful if swallowed. Causes skin
and eye irritation. Suspected of
causing cancer.
N.B. For solvents (like ethanol) or drying agents (e.g. sodium sulfate), you don’t
need to calculate the moles.
* Report only when applicable
* Mass and moles may change depending on the exact weight measured in the lab.
Name
Exp # 5 and 6
Date:
Lab Partner:
4. Calculations: Shown each calculation for moles of reagents, limiting reagent, theoretical yield
and percent yield. (4 points)
Determining limiting reagent:
0.5 𝑔𝑟𝑎𝑚𝑠 𝑜𝑓 𝑓𝑙𝑢𝑜𝑟𝑒𝑛𝑜𝑛𝑒
1
1 𝑚𝑜𝑙𝑒 𝑜𝑓 𝑓𝑙𝑢𝑜𝑟𝑒𝑛𝑜𝑛𝑒
× 180.2 𝑔 𝑜𝑓 𝑓𝑙𝑢𝑜𝑟𝑒𝑛𝑜𝑛𝑒 = 0.00277369 mol from fluorenone = 0.0028 mol fluorenone
0.05 𝑔 𝑠𝑜𝑑𝑖𝑢𝑚 𝑏𝑜𝑟𝑜ℎ𝑦𝑑𝑟𝑖𝑑𝑒
1 𝑚𝑜𝑙 𝑜𝑓 𝑠𝑜𝑑𝑖𝑢𝑚 𝑏𝑜𝑟𝑜ℎ𝑦𝑑𝑟𝑖𝑑𝑒
4 𝑚𝑜𝑙 𝑜𝑓 𝑓𝑙𝑢𝑜𝑟𝑒𝑛𝑜𝑙
× 37.83 𝑔 𝑜𝑓 𝑠𝑜𝑑𝑖𝑢𝑚 𝑏𝑜𝑟𝑜ℎ𝑦𝑑𝑟𝑖𝑑𝑒 × 1 𝑚𝑜𝑙 𝑜𝑓 𝑠𝑜𝑑𝑖𝑢𝑚 𝑏𝑜𝑟𝑜ℎ𝑦𝑑𝑟𝑖𝑑𝑒 = 0.0052 mol sodium
1
borohydride
The limiting reagent is: Fluorenone
Calculating theoretical yield:
182.22 𝑔𝑟𝑎𝑚𝑠 𝑜𝑓 𝑓𝑙𝑢𝑜𝑟𝑒𝑛𝑜𝑛𝑒
1 𝑚𝑜𝑙 𝑜𝑓 𝑓𝑙𝑢𝑜𝑟𝑒𝑛𝑜𝑛𝑒
×
= 0.51 grams
1 𝑚𝑜𝑙
1
The actual yield is 0.73 grams
𝐴𝑐𝑡𝑢𝑎𝑙 𝑦𝑖𝑒𝑙𝑑
0.73 𝑔
Calculating Percent yield: 𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑦𝑖𝑒𝑙𝑑 ×100 = 0.51 𝑔 ×100 = 143%
Reaction percent yield is: 143%
5. Procedure, Observations and Data
Procedure (4 point)
Observations and Lab Data (4 point)
A summary of the procedure done with bullet points)
(2 points)
Report all observations and all data that you collect in the
PART I
● Using premade TLC plates (for 0, 15,
30, 60, 120 and 180 seconds) take a
pencil and draw equally spaced marks
about 5-7 mm from the bottom of the
plate
○ Have them 5 mm apart (workon
the dull side!)
lab here
Part I:
An empty round bottom flask was obtained and
measured to be 36.64 grams. The keton utilized is
yellow and alcohol is colorless.
Name
Exp # 5 and 6
Date:
Lab Partner:
● Do not make a mark too close to the
For each time interval a TLC plate was spotted with
sides. On each plate, spot the first mark
with the starting material (fluorenone) the appropriate time frame. They were made equally
and the last with the product
spaced apart with no TLC spots too close together or
(fluorenol) using different
micropipettes.
close to the edge.
● The marks between these two will be
Approximately 0.50 grams of fluorenone were
for the reaction mixture.
● The number of spots between the
starting material and product spots
depends on the size of the TLC plates
you use.
obtained. Once the TLC plates were made and the
time intervals collected there was a reference
compound of fluorenone that was obtained from the
● Next, accurately weigh out about 0.5 g
of fluorenone in a 50 mL round bottom
flask.
instructor.
2 additional mL of methanol were added along with 2
● Add 10 mL of methanol and a stir bar.
more mL which came to a total of about 4 mL of
● Stir until dissolved.
MeOH added.
●
●
Using a new micropipette, spot the
plate at the 0-time point.
Weigh out about 0.05 g of NaBH4 and
quickly add it to the reaction.
● At each of the designated time points
(15, 30, 60, 120 and 180 seconds),
remove a sample with a clean
micropipette and spot the appropriate
TLC plate.
● Develop the plates in a developing
chamber containing methylene
chloride (5 mL).
● Mark the solvent front when you
remove the plates from the chamber
and visualize the spots using the
ultraviolet lamp.
The solute was not yet dissolved.
Name
Exp # 5 and 6
Date:
Lab Partner:
● Calculate the Rf of the starting material
and product.
○ Record your results in your
notebook.
● Transfer the reaction to a 50 mL
Erlenmeyer flask and add 3 mL of
water and heat until all the solid
dissolves
● Cool to room temperature to induce
crystallization and then put in an
ice-bath to complete the process.
Once the solution was obtained the ice bath was added
and some crystals started to form over time.
● Collect the crystals using a buchi funnel
Once the crystals were collected they were added to
and dry by pulling air through the
funnel for 10 min
the funnel and after about 10 minutes the crude
● Weigh the crystals and determine a
product was formed.
melting point
● Record the Rf and percent yield of the
product.
PART II
Part II:
● Weigh out 15 g of silica gel and pour
them into a 50 mL Erlenmeyer flask.
About 10 g of silica gel was obtained which at first
● Add 15 ml of solvent mixture (9/1
hexane: ethyl acetate) to the
Erlenmeyer flask containing the silica
gel and swirl the Erlenmeyer flask to
ensure that all of the silica is well
solvated
● Clamp the column in the vertical
position to a ring stand.
glance is a white powder. Once the silica gel was
added 20 mL of 9/1 hexane ethyl/acetate ( a visible
clear liquid) was added into the mixture. After that
was completed about 45 mL of 9/1 were used in total
Name
Exp # 5 and 6
Date:
Lab Partner:
● Using a funnel, gently pour the
to aid in the cleaning of the column to ensure best
prepared slurry of silica gel into the
possible results since we rinsed the inner walls.
column. You may need to add
additional solvent to transfer the slurry
Tapping the column is essential to allow bubbles to
from the Erlenmeyer flask to the
column
rise and make silica gel and sand more compact.
● Using a pipette, wash down any silica
Always remember to allow the stopper to drain a few
gel that sticks to the sides of the
column.
drops to get rid of any unnecessary impurities.
● As silica gel is settling in the column,
gently tap the sides of the column
● Open the stopcock and allow solvent to
drain into a clean Erlenmeyer flask
until just before the silica gel and the
solvent front meet
● The silica gel should never go dry until
the procedure is complete.
● Place a thin layer of sand on top of the
silica gel. Using a pipette, wash down
any sand that may have stuck to the
sides of the column.
●
Drain any additional solvent until the
sand is dry, but not down to the silica
gel layer
● Dissolve 0.2 g of the crude product in 3
mL of methylene chloride and using a
pipette, gently add the sample to the
top of the column
● Once the sample has been applied to
the top of the column, open the
stopcock and allow the solvent to drain
through the sand layer only
The crude product was obtained and it appeared white
and fluffy. The crude product was measured in a vial
to be approximately 15.44 grams but once the crude
product was removed it was found that the crude
weight was 0.73 grams. However, we were only using
Name
Exp # 5 and 6
Date:
Lab Partner:
● Use a very small amount of solvent to
wash down any sample that may have
clung to the sides of the column
0.2 grams of the crude product which was let to
● Drain this additional solvent through
the sand layer as well.
mL were used to help dissolve) As the column
dissolve in 5 mL of methylene chloride ( a total of 20
chromatography experiment went on about 30 mL of
● Using a pipette, very gently add 4–5 mL
9/1 hexane EA was added and finally 50 mL of 3/1
of solvent mixture (9/1 hexane: ethyl
acetate)
hexane/ EtoAc was finally added.
● Place a funnel at the top of the column
and very slowly and gently fill the
remainder of the column with solvent
mixture (9/1 hexane: ethyl acetate, 50
mL).
● Open the stopcock and allow the
solvent to drain
● Begin collecting the mobile phase as it
drains from the column into test tubes
● When you have 8 mL in test tube 1,
move to test tube 2 to collect another 8
mL.
● Continue collecting 8 mL fractions in
this manner for test tubes 1-6 and then
switch to a 75:25 hexane: ethyl acetate
mixture (50 mL) and collect the
remaining another 6 fractions
Dichloromethane and crude product were mixed in as
● Add additional solvent to the top of the
column as needed until all the desired
compounds have been removed from
the column
chamber were set up beforehand to help with a
a reference point to use in the TLC chamber
experiment part of the laboratory.TLC plates and
smoother transition between laboratory experiment
steps.
● Obtain four large TLC plates from the
instructor. Prepare the plates as before.
Name
Exp # 5 and 6
Date:
Lab Partner:
● Dissolve the product from the
fluorenone reduction in 3 mL of
methylene chloride and spot the
solution on the first mark on each
plate, this is your standard.
● The remaining marks on each plate will The darkest point will be used to determine the boiling
be for the fractions collected from the
point and the round bottom flask determination will
column.
● Identify the test tubes that contain the
desired product and combine all of the
fractions that contain the desired
isolated compound into a pre-weighed
round-bottom (RB) flask.
occur as well.
● Evaporate the solvent by placing the
round bottom flask on the rotary
evaporator.
about 48.77 grams.
The pre weight of the round bottom flask is about
48.64 grams and then the RB with the product was
The melting point recorded for the crude product was
● Once all of the solvent has been
about 113.7 oC. The R(f) value was calculated to be
removed, weigh the round bottom flask
(distance traveled/ total distance; 1.9 cm/5.5 cm)
with the dried product and subtract
the initial weight of the RB to obtain a
which gave an R(f) value of 0.34 cm.
yield.
● Obtain a melting point and calculate
your yield.
The percent yield turned out to be approximately
143% for this laboratory experiment. The actual yield
was about 0.73 grams as obtained from the crude
weight.
Name
Exp # 5 and 6
Date:
Lab Partner:
Conclusions and discussions (4 points)
Through the lab experiment it was found that the white fluffy crude product of fluorenol had a
boiling point of about 113.7 oC and was the purest form of 9-fluorenol. The two part laboratory
enriched TLC chamber assembly skills as well as TLC spotting and visualization methods.
Successful follow through from the stationary phase to the mobile phase was carried out by
collecting it via test tubes. After using the visualization method it was found that the tube labeled
#8 closely resembled the reference spots of the product. The R(f) value was subsequently
calculated following the equation that R(f)= Distance Traveled/ Total Distance and it was found to
be about 0.34 centimeters. After placing the round bottom flask first the original weight was 48.64
grams and with the product it was 48.77 grams, giving us a yield of 0.13 grams, in other words a
pure form of the crude product.
7. References:
1. Fluorenone reduction. Odinity. (2017, December 17). Retrieved October 5, 2021,
from https://www.odinity.com/fluorenone-reduction/.
2. Gao, X. (n.d.). Experiment 5 & 6: TLC & Flash Chromatography. BlackBoard.
Retrieved October 5, 2021, from
https://caldwell.blackboard.com/webapps/portal/execute/tabs/tabAction?tab_tab_
group_id=_1_1.
8. Image of your lab notebook. (3 point)
Name
Lab Partner:
Exp # 5 and 6
Date:
Name
Lab Partner:
Exp # 5 and 6
Date:
Name
Lab Partner:
Exp # 5 and 6
Date:
Name
Lab Partner:
Exp # 5 and 6
Date:
Name
Lab Partner:
Exp # 5 and 6
Date:
Name
Lab Partner:
Exp # 5 and 6
Date: