GUIDED-INQUIRY PROJECTS AND EXPERIMENTS CHRISTINA NORING HAMMOND VASSAR COLLEGE POUGHKEEPSIE, NY

1
GUIDED-INQUIRY PROJECTS AND
EXPERIMENTSCHRISTINA NORING HAMMONDVASSAR
COLLEGEPOUGHKEEPSIE, NY
2
MONDAY LAB Experiment 10 E2 ELIMINATION OF
2-BROMOHEPTANE INFLUENCE OF THE BASE QUESTION
What effect does the bulkiness of the base have
on the product composition in the E2
debromination of 2-bromoheptane?
Microscale procedure Students work in
teams of two with one using each base.
Product composition determined by GC analysis.

3
EXP. 8.1 RADICAL CHLORINATION
REACTIONS QUESTION Do statistical factors
determine the product composition in radical
chlorination reactions or do electronic factors
play a role? Green Chemistry Cl2 is
generated in situ from household bleach (5.25
NaOCl) and 3 M HCl Substrates
used Microscale experiment.
Teamwork. Irradiation with 300-watt
unfrosted incandescent bulb until the yellow
color of Cl2 disappears (5 min).
Product mixture analyzed by GC.

4
EXP 8.2 PHOTOBROMINATION OF 1,2-DIPHENYLETHANE Q
UESTION Which diastereomer forms in the
photobromination of
1,2-diphenylethane? Green Chemistry
Bromine is generated in situ
Irradiation done with 100-watt incandescent bulb
for 10 min. Product analyzed by m.p.
5
PROJECT 6 E1/E2 ELIMINATION REACTIONS
QUESTION Compare the mixture of isomeric
alkenes produced by an acid- catalyzed
dehydration and a base-catalyzed
dehydrochlorination. Are the product ratios
influenced primarily by product stability?
Two-week project for a team of two
students.
6
PROJECT 6 E1/E2 ELIMINATION REACTIONS
Project 6.1 Acid-Catalyzed Dehydration of
2-Methyl-2-butanol QUESTION Does product
stability or do statistical factors determine the
ratio of 2-methyl-2-butene to 2-methyl-2-butene?
Project 6.2 Synthesis of 2-Chloro-2-methylbu
tane PURPOSE To synthesize 2-chloro-2-methylbuta
ne for use in a
dehydrochlorination reaction.
7
PROJECT 6 E1/E2 ELIMINATION REACTIONS
Project 6.3 Base-Catalyzed Dehydrochlorination
of 2-Chloro-2-methylbutane QUESTION Does
product stability or do statistical factors
determine the ratio of 2-methyl-2-butene to
2-methyl-2-butene?
Both students run the reaction using
product prepared in 6.2.
8
Project 4
INTERCONVERSION OF 4-tert-BUTYCYCLOHEXANOL AND
4-tert-BUTYCYCLOHEXANONE
QUESTION What is the stereoselectivity of NaBH4
reduction of
4-tert-butylcyclohexanone? Project 4.1 Green
Chemistry Sodium Hypochlorite Oxidation of
4-tert-Butylcyclohexanol Rate of
reaction dependent on rate of stirring.
When is the reaction complete? Reaction
monitored by TLC analysis using p-anisaldehyde
visualization.
9
INTERCONVERSION OF 4-tert-BUTYCYCLOHEXANOL
AND 4-tert-BUTYCYCLOHEXANONE
Project 4.2 Sodium Borohydride Reduction of
4-tert-Butylcyclohexanone
Reaction can be monitored by TLC. Product
analysis by GC and/or NMR. -trans isomer
axial proton on C with --OH at 3.5 ppm. -cis
isomer equatorial proton at 4.03 ppm.
10
PROJECT 12 BIOCHEMICAL CATALYSIS AND THE
STEREOCHEMISTRYOF BOROHYDRIDE REDUCTION
QUESTION What the stereoselectivity in
the sodium borohydride reduction of benzoin to
1,2-diphenyl-1,2-ethanediol? PROJECT 12.1
Green Chemistry Traditional catalyst, KCN, is
replaced with thiamine. Benzoin
condensation is first step in a three-step
project.

11
PROJECT 12 BIOCHEMICAL CATALYSIS AND THE
STEREOCHEMISTRYOF BOROHYDRIDE REDUCTION
PROJECT 12.2 Cyclic acetal
analyzed by NMR.
12
PROJECT 12 BIOCHEMICAL CATALYSIS AND THE
STEREOCHEMISTRYOF BOROHYDRIDE REDUCTION
NMR analysis by chemical shifts of the -CH3
groups and the methine protons.
13
PROJECT 14 SUGARS GLUCOSE PENTAACETATES
QUESTIONS What is the relative stability of ?-
and ?-D-glucose pentaacetate?
How can you distinguish between kinetic and
equilibrium control in
the synthesis of the glucose pentaacetates?
PROJECT 14.1 Synthesis of ?- and ?-D-Glucose
Pentaacetate
14
PROJECT 14 SUGARS GLUCOSE PENTAACETATES
PROJECT 14.2 Investigation of Kinetic and
Equilibrium Control in the Glucose
Pentaacetate System PRELABORATORY
ASSIGNMENT Analyze NMR spectra of both crude
and recrystallized ?- and ?-D-glucose
pentaacetates. C-1 (anomeric) protons ?-
glucose, 6.33 ppm ?- glucose, 5.72 ppm.
Determine ratio of ?- and ?-D-glucose
pentaacetate in each sample. Are the
recrystallized samples at least 95 pure?
Design a set of experiments to investigate the
equilibration of ?- and ??????-D-glucose
pentaacetates. Students are given two
isomerization methods to use for the tests.
NMR analysis of all products.
15
PROJECT 14 SUGARS GLUCOSE PENTAACETATES
PROJECT 14.3 Computational Chemistry
Experiment In aq. solutions of ?-glucose
anomer, the C-1 hydroxyl group is
equatorial ????and with the??-glucose anomer, the
C-1 hydroxyl group is axial. Build models of
axial- and equatorial-isomers of
Calculate heats of formation for each isomer.
Use difference in heats of formation for the
2-acetoxytetrapyran conformers to
calculate Keq for ?- and ?-D-glucose
pentaacetate. Are your calculations
consistent with your investigations of kinetic
and equilibrium control in the glucose
pentaacetate system?
16
ACKNOWLEDGEMENTS
Paul F. Schatz, University of Wisconsin
Colleagues and students at Vassar and
Carleton Jhong Kim, UC Irvine My
many Vassar student assistants W. H.
Freeman and Co, publishers
17
(No Transcript)
18
(No Transcript)
19
PROJECT 9 BROMINATION OF CYCLOHEX-4-ENE-cis-1,2-
DICARBOXYLIC ACID
QUESTION What is the stereochemistry of bromine
addition to the double bond? A three-step
synthesis project. First step Diels-Alder
synthesis and subsequent hydrolysis of
anhydride. Pyridinium tribromide is the
source of Br2. Dimethyl ester is
subsequently prepared and stereochemistry
determined by NMR.
20
PROJECT 9 BROMINATION OF CYCLOHEX-4-ENE-cis-1,2-
DICARBOXYLIC ACID
anti Addition of Bromine Bromonium ion pathway.
syn Addition of Bromine Carbocation pathway.
21
TUESDAY LAB
GREEN CHEMISTRY SYNTHESIS AND HYROGENATION
OF SUBSTITUTED CHALCONES A GUIDED-INQUIRY
PROJECT QUESTION Which functional groups are
reduced in the hydrogenation
of a polyfunctional molecule? Part 1
Synthesis of the Chalcone

Use concentrated aqueous NaOH solution for
reaction. Product recrystallized from 95
ethanol. Product analyzed by IR and
NMR. Reference Palleros, D. R. J. Chem. Educ.
2004, 81, 13451347.
22
GREEN CHEMISTRY SYNTHESIS AND HYROGENATION OF
SUBSTITUTED CHALCONES A GUIDED-INQUIRY PROJECT
Part 2 Hydrogenation of the Chalcone
Determine a suitable TLC solvent for the
chalcone. Completion of reaction determined
by TLC analysis. Product analyzed by TLC, IR,
NMR, and GC-MS.