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

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Presentation on theme: "GUIDED-INQUIRY PROJECTS AND EXPERIMENTS CHRISTINA NORING HAMMOND VASSAR COLLEGE POUGHKEEPSIE, NY."— Presentation transcript:

1 GUIDED-INQUIRY PROJECTS AND EXPERIMENTS CHRISTINA NORING HAMMOND VASSAR COLLEGE POUGHKEEPSIE, 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 Microscale procedure Students work in teams of two with one using each base. Students work in teams of two with one using each base. Product composition determined by GC analysis. 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: Cl 2 is generated in situ from household bleach (5.25% NaOCl) Green Chemistry: Cl 2 is generated in situ from household bleach (5.25% NaOCl) and 3 M HCl: and 3 M HCl: Substrates used: Substrates used: Microscale experiment. Microscale experiment. Teamwork. Teamwork. Irradiation with 300-watt unfrosted incandescent bulb until the yellow color Irradiation with 300-watt unfrosted incandescent bulb until the yellow color of Cl 2 disappears (~5 min). of Cl 2 disappears (~5 min). Product mixture analyzed by GC. Product mixture analyzed by GC.

4 EXP 8.2: PHOTOBROMINATION OF 1,2-DIPHENYLETHANE QUESTION: Which diastereomer forms in the photobromination of 1,2-diphenylethane? 1,2-diphenylethane? Green Chemistry: Bromine is generated in situ: Green Chemistry: Bromine is generated in situ: Irradiation done with 100-watt incandescent bulb for ~10 min. Irradiation done with 100-watt incandescent bulb for ~10 min. Product analyzed by m.p. 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. 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-methylbutane PURPOSE: To synthesize 2-chloro-2-methylbutane for use in a dehydrochlorination reaction. 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. Both students run the reaction using product prepared in 6.2.

8 INTERCONVERSION OF 4-tert-BUTYCYCLOHEXANOL AND 4-tert-BUTYCYCLOHEXANONE QUESTION: What is the stereoselectivity of NaBH 4 reduction of 4-tert-butylcyclohexanone? 4-tert-butylcyclohexanone? Project 4.1 Green Chemistry: Sodium Hypochlorite Oxidation of 4-tert-Butylcyclohexanol Rate of reaction dependent on rate of stirring. Rate of reaction dependent on rate of stirring. When is the reaction complete? When is the reaction complete? Reaction monitored by TLC analysis using p-anisaldehyde visualization. Reaction monitored by TLC analysis using p-anisaldehyde visualization. Project 4

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. Reaction can be monitored by TLC. Product analysis by GC and/or NMR. 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 PROJECT 12.1 Green Chemistry: Traditional catalyst, KCN, is replaced with thiamine. Green Chemistry: Traditional catalyst, KCN, is replaced with thiamine. Benzoin condensation is first step in a three-step project. 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. Cyclic acetal analyzed by NMR.

12 PROJECT 12: BIOCHEMICAL CATALYSIS AND THE STEREOCHEMISTRYOF BOROHYDRIDE REDUCTION NMR analysis by chemical shifts of the -CH 3 groups and the methine protons. NMR analysis by chemical shifts of the -CH 3 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 How can you distinguish between kinetic and equilibrium control in the synthesis of the glucose pentaacetates? in the synthesis of the glucose pentaacetates? PROJECT 14.1 Synthesis of  - and  - D -Glucose Pentaacetate 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 Glucose Pentaacetate System PRELABORATORY ASSIGNMENT: Analyze NMR spectra of both crude PRELABORATORY ASSIGNMENT: Analyze NMR spectra of both crude and recrystallized  - and  - D -glucose pentaacetates. and recrystallized  - and  - D -glucose pentaacetates. C-1 (anomeric) protons:  - glucose, 6.33 ppm;  - glucose, 5.72 ppm. C-1 (anomeric) protons:  - glucose, 6.33 ppm;  - glucose, 5.72 ppm. Determine ratio of  - and  - D -glucose pentaacetate in each sample. Determine ratio of  - and  - D -glucose pentaacetate in each sample. Are the recrystallized samples at least 95% pure? Are the recrystallized samples at least 95% pure? Design a set of experiments to investigate the equilibration of  - and 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. Students are given two isomerization methods to use for the tests. NMR analysis of all products. 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 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: Build models of axial- and equatorial-isomers of: Calculate heats of formation for each isomer. Calculate heats of formation for each isomer. Use difference in heats of formation for the 2-acetoxytetrapyran conformers Use difference in heats of formation for the 2-acetoxytetrapyran conformers to calculate K eq for  - and  - D -glucose pentaacetate. to calculate K eq for  - and  - D -glucose pentaacetate. Are your calculations consistent with your investigations of kinetic and Are your calculations consistent with your investigations of kinetic and equilibrium control in the glucose pentaacetate system? equilibrium control in the glucose pentaacetate system?

16 Paul F. Schatz, University of Wisconsin Paul F. Schatz, University of Wisconsin Colleagues and students at Vassar and Carleton Colleagues and students at Vassar and Carleton Jhong Kim, UC Irvine Jhong Kim, UC Irvine My many Vassar student assistants My many Vassar student assistants W. H. Freeman and Co, publishers W. H. Freeman and Co, publishers ACKNOWLEDGEMENTS

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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. A three-step synthesis project. First step: Diels-Alder synthesis and subsequent hydrolysis of anhydride. First step: Diels-Alder synthesis and subsequent hydrolysis of anhydride. Pyridinium tribromide is the source of Br 2. Pyridinium tribromide is the source of Br 2. Dimethyl ester is subsequently prepared and stereochemistry determined by NMR. 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? of a polyfunctional molecule? Part 1 Synthesis of the Chalcone Use concentrated aqueous NaOH solution for reaction. Use concentrated aqueous NaOH solution for reaction. Product recrystallized from 95% ethanol. Product recrystallized from 95% ethanol. Product analyzed by IR and NMR. Product analyzed by IR and NMR. Reference:Palleros, D. R. J. Chem. Educ. 2004, 81, 1345–1347.

22 Part 2 Hydrogenation of the Chalcone GREEN CHEMISTRY: SYNTHESIS AND HYROGENATION GREEN CHEMISTRY: SYNTHESIS AND HYROGENATION OF SUBSTITUTED CHALCONES A GUIDED-INQUIRY PROJECT Determine a suitable TLC solvent for the chalcone. Determine a suitable TLC solvent for the chalcone. Completion of reaction determined by TLC analysis. Completion of reaction determined by TLC analysis. Product analyzed by TLC, IR, NMR, and GC-MS. Product analyzed by TLC, IR, NMR, and GC-MS.


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