The instructional organic chemistry laboratory has been substantially improved through the implementation of benchtop NMR analysis. When used in conjunction with unknown reaction components in multi-outcome experiments, NMR analysis transforms the laboratory exercise into an investigative inquiry wherein students elucidate structures for their products and thereby deduce their unknown reaction components. This analytical approach closely models the research laboratory and is a valuable preparatory tool for undergraduate researchers. Three newly developed multi-outcome experiments based upon the Diels-Alder cycloaddition, the synthesis of carboxylic amides, and the Friedel-Crafts alkylation are herein described to illustrate the utility of benchtop NMR analysis in the instructional laboratory.

The authors have developed “sequence response applications” for classroom response systems (CRSs) that allow instructors to engage and actively involve students in the learning process, probe for common misconceptions regarding lecture material, and increase interaction between instructors and students. “Guided inquiry” and “discovery-based learning” are based on the premise that the best learning occurs when students are actively engaged in developing hypotheses and arriving at conclusions for themselves, rather than learning in a passive lecture format. In this regard, we use CRSs to actively engage large lectures of 300+ students, where the traditional interaction between students and instructors is commonly limited to the first several rows of the lecture hall. Moreover, series response applications allow a nearly free response format for questioning students, as opposed to the traditional multiple-choice question format commonly used with CRSs. As such, we have observed that students are more engaged and actively involved in answering questions. This paper provides several examples to illustrate how our stepwise technique can be used to demonstrate the depth of insight into student understanding, even of multistep thought processes, afforded through this stepwise analysis.

1H NMR analysis is an important analytical technique presented in introductory organic chemistry courses. NMR instrument access is limited for undergraduate organic chemistry students due to the size of the instrument, price of NMR solvents, and the maintenance level required for instrument upkeep. The University of Georgia Chemistry Department recently acquired three picoSpin desktop 1H NMR instruments for the undergraduate organic laboratories. These instruments can sit on a standard lab bench, can analyze samples without NMR solvents, and are easily maintained. In this Fischer esterification experiment, students used unknown starting alcohols to synthesize esters through Fischer esterification. Upon completion of the reaction, students identified the unknown starting alcohol via spectral analyses of the products. Over the course of 4 semesters, 704 out of 940 students (75%) correctly identified the starting alcohol and 71% of students surveyed indicated that 1H NMR spectrum was the most helpful identification tool in their analyses. This experiment established for students the utility of NMR spectral analysis and provided them with the opportunity to employ technology commonly used in academic research facilities.

Single-outcome experiments are used in the undergraduate instructional laboratory, particularly for large lectures associated with multiple sections of instructional laboratories, due in large part to efficiencies associated with chemical purchases, experiment preparations, and assessments. Despite the practical advantages, single-outcome experiments are not effective in encouraging students to critically analyze and interpret their acquired individual results. Instead, students are satisfied if their results are the same as or similar to all of their classmates’ results, limiting the opportunity for engagement with the laboratory content. In contrast, multioutcome experiments (MOEs) require students to explore the same chemical reaction or transformation but obtain individual results. Individualization of results is accomplished by using a set of starting materials or reagents, one of which is assigned to each student. Students do not know the identity of the assigned component but may be given possible options for its identity. Students elucidate the identity of their individualized products, using modern analytical techniques such as gas chromatography, Fourier-transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy, and deduce the unknown component of their experiment. An example MOE for the oxidation of alcohols is described herein. A traditional single-outcome experiment that utilized a common household oxidizing agent (hypochlorite bleach), rather than a heavy metal-containing alternative, was modified. For the MOE modification, one unknown secondary alcohol (2-pentanol, 3-pentanol, or 3-methyl-2-butanol) was oxidized using bleach. Each student pair was assigned one of three possible unknown alcohols, all of which were constitutional isomers of secondary alcohols. Students knew the identities of the three possible alcohols. Analysis of their oxidation products was accomplished using FTIR and benchtop 1H NMR spectroscopies. Students interpreted their spectra and deduced the identity of the unknown alcohol they were assigned. This experiment provides a tangible framework to understand the applicability of the oxidation reaction and the utility of FTIR and 1H NMR spectroscopies.

Williamson ether experiments are commonly performed by students in undergraduate organic chemistry instructional laboratory courses. In this multioutcome experiment, students were provided 4-bromophenol and one of three alkyl halides: 1-bromopentane, 1-bromobutane, or 1-bromo-3-methylbutane. The alkyl halides served as the unknown component of the experiment, and students were given these three as unknown candidates. After isolating the product from the reaction mixture, students analyzed their products using FT-IR and benchtop 1H NMR spectroscopies. The experimental results herein summarize the inclusion of this experiment in the large enrollment second-semester organic chemistry laboratory course over four semesters.