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Synthesis of Unsymmetrical Alkynes via the Alkylation of Sodium Acetylides. An Introduction to Synthetic Design for Organic Chemistry Students
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Abstract
This article describes an inquiry-based experiment for the undergraduate organic chemistry laboratory. The use of acetylides as nucleophiles is a common theme used in most organic textbooks as an introduction to retrosynthetic analysis. We have developed a problem-based application of this methodology for the first-semester organic laboratory. In this experiment, students are assigned to work in teams to design a microscale synthesis of an unsymmetrical alkyne using commercially available terminal alkynes and alkyl halides. Team members work collaboratively to perform the synthesis and characterize the resulting products using TLC, IR, and 1H NMR spectroscopy. Depending on the chosen reactants, students observe both substitution and elimination products, or in some cases, no reaction at all. Therefore, data interpretation is an important component of this experiment. Students must determine the composition of their product mixtures by comparison to starting materials. The structures of expected and unexpected products must be elucidated and justified mechanistically. Our students perform this experiment prior to the investigation of elimination reactions in the lecture, which adds a discovery element. This experiment can be performed in two three-hour lab periods; however, advance preparation is required for the synthetic design of an assigned target.
Keywords (Audience):
First-Year Undergraduate / GeneralKeywords (Domain):
Laboratory InstructionKeywords (Feature):
The Microscale LaboratoryKeywords (Pedagogy):
Collaborative / Cooperative LearningKeywords (Subject):
AlkylationCiting Articles
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This article has been cited by 3 ACS Journal articles (3 most recent appear below).
Ni-Catalyzed Sonogashira Coupling of Nonactivated Alkyl Halides: Orthogonal Functionalization of Alkyl Iodides, Bromides, and Chlorides
Oleg Vechorkin, Delphine Barmaz, Valérie Proust and Xile HuJournal of the American Chemical Society2009 131 (34), 12078-12079Ni-Catalyzed Sonogashira Coupling of Nonactivated Alkyl Halides: Orthogonal Functionalization of Alkyl Iodides, Bromides, and Chlorides
Oleg Vechorkin, Delphine Barmaz, Valérie Proust and Xile HuJournal of the American Chemical Society2009 131 (34), 12078-12079Ni-catalyzed Sonogashira coupling of nonactivated, β-H-containing alkyl halides, including chlorides, is reported. The coupling is tolerant to a wide range of functional groups, including ether, ester, amide, nitrile, keto, heterocycle, acetal, and aryl ...
A Simple SN2 Reaction for the Undergraduate Organic Laboratory
John J. Esteb , John R. Magers , LuAnne McNulty , Paul Morgan and Anne M. WilsonJournal of Chemical Education2009 86 (7), 850A Simple SN2 Reaction for the Undergraduate Organic Laboratory
John J. Esteb , John R. Magers , LuAnne McNulty , Paul Morgan and Anne M. WilsonJournal of Chemical Education2009 86 (7), 850A simple procedure for the synthesis of n-butyl naphthyl ether is presented. This procedure represents an easy method for the production of an aryl ether by an SN2 reaction, uses ethanol as an environmentally friendly solvent, and does not require the use ...
A Safer, Discovery-Based Nucleophilic Substitution Experiment
Gail HorowitzJournal of Chemical Education2009 86 (3), 363A Safer, Discovery-Based Nucleophilic Substitution Experiment
Gail HorowitzJournal of Chemical Education2009 86 (3), 363A discovery-based nucleophilic substitution experiment is described in which students compare the reactivity of chloride and iodide ions in an SN2 reaction. This experiment improves upon the well-known "Competing Nucleophiles" experiment in that it does ...
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- Received: August 03, 2009
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