Experiment For Undergraduate Organic Chemistry Laboratory Research Articles

Breaking Amide C-N Bonds in an Undergraduate Organic Chemistry Laboratory.

An undergraduate organic chemistry laboratory experiment involving the breakage of amide C-N bonds is reported. Whereas amides are typically considered stable species due to well-established resonance effects, this experiment allows students to cleave the amide C-N bond in a nickel-catalyzed esterification process. Moreover, students perform the experiment on the benchtop using a commercially available paraffin wax capsule containing the necessary nickel precatalyst and N-heterocyclic carbene ligand. The laboratory procedure introduces students to several modern topics in organic chemistry that are not otherwise well-represented in typical undergraduate organic chemistry curricula, such as amide bond cleavage, transition metal-catalyzed cross-coupling reactions, and nonprecious-metal catalysis.

Rhodium-Catalyzed C–H Amination: A Case Study of Selectivity in C–H Functionalization Reactions

An advanced undergraduate organic chemistry laboratory experiment involving a rhodium-catalyzed intermolecular hydrocarbon C–H oxidation reaction is described. In the initial phase of this lab, students conduct a C–H amination reaction of ethylbenzene and isolate a benzylic amine product. In the second part of the lab, competition experiments are performed to compare the relative rates of C–H insertion with electronically disparate para-substituted ethylbenzene derivatives. Reaction progress is monitored by thin-layer chromatography and the outcome quantitatively assessed using 1H NMR spectroscopy. Data from competition experiments form the basis for a discussion of reaction mechanism including analysis of putative transition structures and relative potential energy barriers for C–H oxidation. Experiments have been designed such that instructors can tailor the level of detail and discussion from introductory to advanced.

Let There Be Light: Hypothesis-Driven Investigation of Ligand Effects in Photoredox Catalysis for the Undergraduate Organic Chemistry Laboratory

An undergraduate organic chemistry laboratory experiment that provides an introduction to the concepts and practices of photoredox catalysis is reported. While undergraduate-level photochemistry experiments typically place emphasis on analytical properties of catalysts rather than synthetic applications, this experiment showcases the power and versatility of photoredox chemistry in modern organic syntheses. A hypothesis-driven approach is utilized as students apply chemical reasoning to formulate hypotheses predicting the relative catalytic activity of Ru(bpy)32+ and Ru(bpm)32+, which differ slightly in ligand structure. Students work collaboratively to obtain conversion data in [2 + 2] cycloadditions catalyzed by Ru(bpy)32+ and Ru(bpm)32+, and use the data to support or refute their hypotheses. The operationally straightforward experimental protocol has been shown to be robust and reproducible, providing unambiguous results that facilitate student interpretation. Furthermore, the experiment trains students in chemical thinking needed for conducting research.

Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling in a Green Alcohol Solvent for an Undergraduate Organic Chemistry Laboratory.

A modern undergraduate organic chemistry laboratory experiment involving the Suzuki–Miyaura coupling is reported. Although Suzuki–Miyaura couplings typically employ palladium catalysts in environmentally harmful solvents, this experiment features the use of inexpensive nickel catalysis, in addition to a “green” alcohol solvent. The experiment employs heterocyclic substrates, which are important pharmaceutical building blocks. Thus, this laboratory procedure exposes students to a variety of contemporary topics in organic chemistry, including transition metal-catalyzed cross-couplings, green chemistry, and the importance of heterocycles in drug discovery, none of which are well represented in typical undergraduate organic chemistry curricula. The experimental protocol uses commercially available reagents and is useful in both organic and inorganic instructional laboratories.

Microwave-Assisted Esterification: A Discovery-Based Microscale Laboratory Experiment

An undergraduate organic chemistry laboratory experiment has been developed that features a discovery-based microscale Fischer esterification utilizing a microwave reactor. Students individually synthesize a unique ester from known sets of alcohols and carboxylic acids. Each student identifies the best reaction conditions given their particular reagents (either excess alcohol or excess carboxylic acid) as well as the ideal workup procedure for their reaction. Products are analyzed using 1H NMR spectroscopy, IR spectroscopy, and scent. This modern adaptation of the classic Fischer esterification provides the opportunity for discussion of important chemistry concepts, including acid catalysis, Le Châtelier’s principle, and green chemistry.

Biodiesel from Seeds: An Experiment for Organic Chemistry

Plants can store the chemical energy required by their developing offspring in the form of triglycerides. These lipids can be isolated from seeds and then converted into biodiesel through a transesterification reaction. This second-year undergraduate organic chemistry laboratory experiment exemplifies the conversion of an agricultural energy source directly into a mechanical energy source.

Undergraduate Laboratory Experiment To Determine Absolute Configuration Using Thin-Layer Chromatography

A new undergraduate organic chemistry laboratory experiment has been developed to determine the absolute configuration of enantioenriched secondary alcohols with the competing enantioselective conversion (CEC) method. The CEC method uses both enantiomers of a chiral kinetic resolution reagent in parallel reactions to identify the fast-reacting reagent and thus the configuration of the alcohol. Students working in pairs are given one of three enantioenriched secondary alcohols with an unknown absolute configuration. They assign the molecular structure using the corresponding 1H NMR spectrum and determine the absolute configuration via the CEC method. The parallel reactions are run at room temperature for 1 h using small quantities of solvent, substrate, and catalyst. Students use thin-layer chromatography (TLC) to analyze the parallel reactions and determine the fast reaction qualitatively. The free program ImageJ is used with a picture of the TLC plate to carry out a quantitative analysis of reaction conv...

The Implementation of a Service-Learning Component in an Organic Chemistry Laboratory Course

Education institutions globally are increasingly expected to explore avenues for the implementation of service-learning into their curricula. A second-year undergraduate organic chemistry laboratory experiment, in which the undergraduate students make azo dyes, can provide a vehicle for a service-learning module in which university undergraduate students then teach students from resource-limited secondary schools how to make azo dyes. Evidence is provided to show how the theory is reinforced for both sets of students through a shared practical experience. The practical application of chemistry is conveyed through the use of the synthetic azo dyes to dye t-shirts. The results of this study show that the service-learning experience clearly assists undergraduate students to appreciate the role of chemists in the broader society while at the same time increasing awareness of the inequalities in school education systems.

The Synthesis and Isolation of N-tert-Butyl-2-phenylsuccinamic Acid and N-tert-Butyl-3-phenylsuccinamic Acid. An Undergraduate Organic Chemistry Laboratory Experiment

This experiment, which demonstrates that two isomeric products are obtained when an unsymmetrical anhydride is reacted with a nucleophile and that these isomers are easily separated based on their difference in acidity, is useful in introducing the topic of carboxylic acid derivatives into the organic chemistry laboratory.

An Undergraduate Organic Chemistry Laboratory Experiment: The Multistep Synthesis of a Modified Nucleoside

We have designed and integrated the multistep synthesis of a modified nucleoside into an undergraduate organic chemistry laboratory. The laboratory was designed as a multidisciplinary approach towards a single synthetic problem. Here we report the synthesis and subsequent purification of 5'-O-dimethoxytrityl-2'-O-methyluridine and 5'-O-dimethoxytrityl-3'-O-methyluridine directly from the literature by a protocol that is appropriate in a small school setting.

Examination of a Reaction Mechanism by Polarimetry: An Experiment for the Undergraduate Organic Chemistry Laboratory

An undergraduate Organic chemistry laboratory experiment involving the use of polarimetry to determine a reaction mechanism is described. The experiment has been shown to be successful with chiral mandelic acid and POCl3 and with chiral lactic acid and HBr. The substitution mechanisms of these reactions proceed with 1% and 38% SN2 character respectively.

Synthesis of cyclopentanecarboxaldehyde: An undergraduate organic chemistry laboratory experiment

The synthesis of cyclopentanecarboxaldehyde can be applied to develop an understanding of the behavior of compounds in many areas of organic chemistry, particularly those of alicyclic compounds.