1 / 22

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

jcarnes
Download Presentation

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

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  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.

More Related