East Tennessee State University Experiment Worksheet

Dr. Irina SmoliakovaChem 340L, Survey of Organic Chemistry Lab
Experiment 8
Topic 1: Oxidation of Alcohols Using Potassium Permanganate
Topic 2: Thin Layer Chromatography
This virtual experiment will be focused on two topics:
a) Oxidation of alcohols using potassium permanganate:

b) Thin layer chromatography:
https://www.youtube.com/watch?v=U2BKeT8toLQ and
https://www.youtube.com/watch?v=e99nsCAsJrw)
The recommended steps of the virtual experiment: a) review oxidation of
alcohols in the Chem 340 textbook, b) read instructor’s PP prelab lecture slides
posted on Bb, c) watch the recommended YouTube videos, d) complete and upload
Report 8, and e) take Lab Quiz 8
Guidelines for Quiz 8 (a total of 10 pts)
1.
Reaction equations for the oxidation of primary and secondary alcohols
using potassium permanganate, KMnO4. Organic and inorganic products of these
reactions.
2.
Oxidation of primary and secondary alcohols by typical oxidants, e.g., PCC,
chromic acid (Jones’ reagent), K2Cr2O7, and KMnO4.
3.
Hydroxyl, carbonyl, and carboxyl functional groups. Primary, secondary
and tertiary alcohols. Aldehydes, ketones and carboxylic acids.
4.
Name, formula, structure, hazards, and role (e.g., a reagent, solvent,
product, additive, drying agent, etc.) of all compounds used in the experiment.
5.
Major steps of the procedure used in the YouTube video describing the
oxidation of 1-butanol to butyric (butanoic) acid.
6.
Reaction of KMnO4 with H2O2.
7.
Equipment, apparatus, and glassware used in the experiment.
8.
Safety issues during the experiment.
9.
Thin layer chromatography as an analytical tool (i) to determine the purity
of organic compounds and (ii) to identify chemicals by comparing their retention
factors with those of reference compounds.
10. What is Rf and how to measure it? What is an eluent? Which factors
influence the Rf value?
Guidelines for Report 8 (a total of 30 pts)
1. Prelab Section (a total of 10 pts):
a) (1 pt) Write your name, course number, lab section number, the number and
title of the experiment.
b) (1 pt) Write the objectives of this experiment.
* This document was prepared by Dr. Smoliakova and used with her permission
1
Dr. Irina Smoliakova
Chem 340L, Survey of Organic Chemistry Lab
c) (a total of 8 pts) Draw and complete Table 1. Please describe all hazards
properly. Do not forget to show your calculations in the report below the Table.
Table 1. Chemicals used in Experiment 8.
Name of the
Compound
Lewis
Structure
of
the
Compound
(2.5 pts)
Physical
State
at Molecular Density
Room Temp. Weight
(g/mL)
and
Appearance
Amount Used
in
g
(for Amount
solids) or mL Used
(for liquids)
Moles
in
Hazards
1-butanol
butanoic
acid
potassium
permanganate
sodium
carbonate
hydrogen
peroxide
calculate and
write in this
box
the
theoretical
yield of the
product
in
grams
using
the amounts
mentioned in
the video (2
pts)
calculate
and write in
this box the
theoretical
yield of the
product
in
moles using
the amounts
mentioned in
the video
(1 pt)
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
2. Observation and Results Section (a total of 20 pts)
a) (4 pts) Watch the following video:

Describe everything that the chemists did during the experiments shown in
the video. You should use the past tense. Write complete sentences. Be concise
(limit your writing to 1 page). A good description of the experiment is the one ,
which can be given to another student to reproduce the experiment. Be sure to use
the correct names of all pieces of equipment and all steps of the procedures.
b) After watching the video, answer the following questions in your lab notebook:
i) (1 pt) Write the equation for the preparation of butanoic acid (also known
as butyric acid) described in the video:
the structure of the organic reactant + the formula of the oxidant à the structure of
butanoic acid + the formula of the Mn-containing by-product
Do not balance the equation.
ii) (2 pts) What organic solvent is used for the extraction of butanoic acid?
Provide (1) the Lewis structure, (2) common name and (3) IUPAC name
of that solvent.
iii) (1 pt) What layer- bottom or top – does this solvent form when it is mixed
with water? Why?
iv) (1 pt) What was the purpose of using MgSO4 in the experiment?
2
Dr. Irina Smoliakova
v)
Chem 340L, Survey of Organic Chemistry Lab
(1 pt) What was the purpose of using H2O2 in the experiment? Support
your answer by writing the equation.
(2 pts) Assume that the student isolated 3.95 mL of pure butanoic acid.
Calculate the percent yield of the product. Provide your calculations.
(1 pt) Write the equation for the oxidation of 3-methyl-2-butanol by
potassium permanganate:
vi)
vii)
the structure of 3-methyl-2-butanol + the formula of the oxidant à the
structure of the organic product + the formula of the Mn-containing byproduct
viii)
Do not balance the equation.
(1 pt) Write the equation for the oxidation of 3-methyl-1-pentanol by
chromic acid:
the structure of 3-methyl-1-pentanol + H2CrO4 à the structure of the
organic product.
ix)
Do not balance the equation.
(1 pt) Write the equation for a possible reaction of 3-methyl-1-pentanol
with PCC:
the structure of 3-methyl-1-pentanol + structure of PCC à the
structure of the organic product.
Do not balance the equation.
c) Watch the following TWO videos:
https://www.youtube.com/watch?v=U2BKeT8toLQ and
https://www.youtube.com/watch?v=e99nsCAsJrw)
After watching those two videos, answer the following questions:
i) (1 pt) Provide two major purposes of using thin layer chromatography on
organic chemistry labs.
ii) (1 pt) Should students use concentrated or diluted solutions of the analyte
for spotting? Why?
iii) (1 pt) Which two visualization methods for TLC plates are commonly used
in organic labs?
iv) (2 pts) Determine the Rf value of the unknown compound using the
following data. Show your calculations.
start
70 mm
75 mm
110 mm
110 mm
.
120 mm
solvent front
3
12/25/21
Experiment 8
OXIDATION OF 1-BUTANOL USING
POTASSIUM PERMANGANATE
THIN-LAYER CHROMATOGRAPHY
1
1
Purposes of Experiment 8
• Learn how to oxidize primary alcohols to carboxylic acid
using KMnO4 (potassium permanganate, a strong oxidizing
agent).
• Learn a new technique, thin layer chromatography,
commonly used to analyze the purity and identity of organic
compounds.
2
2
1
12/25/21
Oxidation of n-Butanol to Butyric Acid
• n-Butanol (also known as 1-butanol) is a primary alcohol, which
can be readily oxidized by several oxidizing reagents, e.g., H2CrO4
(chromic acid, prepared by mixing CrO3, H2O and H2SO4), K2Cr2O7
(potassium dichromate), pyridinium chlorochromate (PCC), and
KMnO4 (potassium permanganate).
• In Exp. 8, 1-butanol will be oxidized by KMnO4:
OH
KMnO4
OH
+ MnO2
O
• The carbon bonded to the hydroxyl group is oxidized (the carbon
formally gives away electrons), while Mn(7+) is reduced to Mn(4+)
(it gains three electrons).
3
3
Product Identification Using
Thin Layer Chromatography
• Chromatography is a set of techniques used for the separation
of mixtures.
• There are preparative and analytical chromatography
techniques. Analytical chromatography is used (i) to check the
purity of a compound, (ii) to identify an unknown compound
using a reference, and (iii) to monitor the reaction progress.
• Most common types of chromatography are (i) column and (ii)
thin layer chromatography (TLC).
4
4
2
12/25/21
TLC
A. A diluted solution of the analyte is spotted on a strip of plastic or glass covered with a
thin layer of silica gel (SiO2, an adsorbent). In the picture shown below, the same
solution is spotted three times using different amounts.
B. The strip called a TLC plate is placed into a covered jar containing a few milliliters of a
solvent or a mixture of solvents. A solvent or a mixture of two or more miscible
solvents used in TLC is called an eluent.
C. As a solvent rises on the TLC plate, the components of the analyte rise as well. The
more strongly a given component of the mixture is adsorbed on silica gel, the more
slowly it will move up the TLC plate. Different compounds will move up the plate at a
different speed. The plate is removed from the jar when the eluent reaches the top
(or almost the top) of the TLC plate.
http://en.wikipedia.org/wiki/Chromatography
5
5
Visualization of the Chromatogram
• The chromatogram must be visualized when the analyte is
colorless. The most common methods are the use of I2 and UV
light. Iodine vapors are adsorbed by many compounds to form
a brown spot on the TLC plate. UV light is absorbed by many
compounds to create a bright spot.
6
6
3
12/25/21
Retention Factor, Rf
solvent front
X mm
Compound A: Rf =
Z
X
Compound B: Rf =
Y
X
Ymm
Z mm
.
.
pure
pure
compound A compound B
.
mixture of
A and B
starting spots
depth of solvent
A pure compound must have only one spot
on a TLC plate.
Chemists measure the retention factor (Rf)
value of each component of the analyte. The
Rf value is a ratio of the distance the
compound traveled from the place of spotting
(distances Z and Y for compounds A and B,
respectively, as shown on the Figure) to the
distance traveled by the eluent (X). The Rf
value is constant for a particular compound
and measured using a specific eluent on the
given type of the TLC plate.
More polar compounds usually have lower
Rf values than non-polar substances. The
higher the solvent polarity, the higher the Rf
7
value.
7
4

Essay writing service:

• Excellent quality
• 100% Turnitin-safe
• Affordable prices

Order Now