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

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

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

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  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 QUESTION: 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-methylbutane PURPOSE:To synthesize 2-chloro-2-methylbutane 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. 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.

  18. 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.

  19. TUESDAYLAB 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, 1345–1347.

  20. 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.

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