I. Developing Methods for the Analysis of Chemistry Students' Inscriptions, II. Exploring the Regioselectivity of 1,3-Dipolar Cycloadditions of Munchnones, III. Stereochemical Investigations of C-H Activation Reactions Involving Germylene and Stannylene/A

[摘要] I. Analyzing and comparing student-generated inscriptions in chemistry is crucial to gaining insight into students’ understanding about chemistry concepts.Thus, we developed two methods of analyzing student-generated inscriptions: features analysis and thematic analysis. We have also demonstrated how these methods are able to discern differences between both how students inscribe their understandings and the content of those inscriptions, regardless of 1) how those inscriptions were created (ie. computer vs. pencil-and-paper), 2) the nature of the inscriptions (verbal vs. pictorial), and 3) the expertise of the students.The ability to analyze inscriptions regardless of the medium allows the examination of multiple inscriptions in educational research applications as well as in the design and development of educational materials.Also, inscriptions can be compared across contexts, allowing the comparison of student-generated inscriptions derived from various educational interventions.Finally, the ability to compare inscriptions regardless of the level of expertise allows novice/expert comparisons as well as longitudinal comparison over time.II. Predicting the regiochemistry of 1,3-dipolar cycloadditions of münchnones and acetylenic dipolarophiles is difficult based on frontier molecular orbital theory (FMO) alone.We have proposed that, in addition to FMO considerations, steric factors influencing the non-covalent interactions between reactive centers in the transition state also influence the regioselectivity of these reactions.We have developed a scheme to use a tether-based regiocontrol strategy to synthesize 2,4-disubstituted pyrroles using N-(2-thiazolinyl) secondary amino acid derivatives.Attempts to synthesize these amino acid derivatives have been, so far, unsuccessful.III. To provide additional information about the mechanism of C-H activation reactions of stannylenes and germylenes, and to demonstrate the utility of these reactions, we explored inducing stereochemistry at the C-H activation site as well as determining the corresponding stereoselectivity.Attempts at induction produced a racemic mixture of products. Products from C-H activation reactions of chiral 2-methoxybutane could not be analyzed with a chiral NMR shift reagent, Europium(III) tris[3-(heptafluoropropylhydroxymethylene)-d-camphorate], (Eu(hfc)3).However, NMR studies of the substrate revealed no scrambling of the stereocenter of chiral substrates occurs during the reaction. In addition, Eu(hfc)3 was shown effective for determining the %ee of these reactions for products with sterically unencumbered oxygen atoms.

[发布机构] University of Michigan

[效力级别] Chemistry Education

[关键词] Discourse Analysis;Chemistry Education;C-H Activations;Dipolar Cycloadditions;Inscriptions;Science Education;Linguistics;Chemistry;Education;Humanities;Science;Social Sciences;Education and Chemistry