A Mixed-Aldol Condensation Reaction with Unknown Aldehydes and Ketones: Employing Modern Methods To Improve the Learning Process for Second-Year Undergraduate Organic Chemistry Students

Balija, Amy M.; Reynolds, Aileen M.

doi:10.1021/ed300454d

Cited by 17 publications

(12 citation statements)

References 7 publications

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“…Melting points for all eight products are reported in the literature. 4 Interpreting Student Observations Some reactions showed a yellow or orange color after only a few seconds but were slow to form precipitate, while others showed observable color only immediately before heavy precipitation of product started. When pointed out to the class during a 20 min discussion at the end of the lab, it was easy for students to see that appearance of color in the reaction had little correlation with a reaction proceeding fast or slow.…”

Section: Running the Experimentsmentioning

confidence: 63%

“…The damp product is recrystallized from hot 95% ethanol, providing yields up to 95%. Melting points for all eight products are reported in the literature …”

Section: Discussionmentioning

confidence: 99%

“…The products are generally easy to purify and characterize, and the aldol reaction exhibits canonical mechanistic steps that link the lab exercise back to important concepts students learn in lecture. This Journal has published many Laboratory Experiments involving aldol reactions, including the following: exercises focusing on multistep synthesis; − purification and identification of unknown aldol products; , spectroscopic characterization using NMR, IR, MS, and UV techniques; − chiral catalysis, chiral separations, and optical rotation; − and development of greener lab procedures. − …”

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confidence: 99%

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Aldol Condensation Reaction Rate Demonstrates Steric and Electronic Substituent Effects in the Organic Chemistry Lab

et al. 2021

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Aldol chemistry is highlighted in many introductory organic chemistry laboratory experiments because it provides synthesis, mechanism, and experimental challenges for students. In the experiment described here, students synthesize dibenzalacetone derivatives by crossed aldol condensation, observe reaction rates using a semiquantitative rubric, and illustrate the connection between reactant structures and reaction rate through their knowledge of the reaction mechanism. By combining class data and working through a guided-inquiry questionnaire, students link reaction rates with nucleophile and electrophile characteristics of the reactant structures. Independent rate determination of the aldol addition step, using UV absorption, confirmed that student rate observations of the overall reaction are a valid approach to learning about structure–function effects.

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Section: Running the Experimentsmentioning

confidence: 63%

“…The damp product is recrystallized from hot 95% ethanol, providing yields up to 95%. Melting points for all eight products are reported in the literature …”

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Aldol Condensation Reaction Rate Demonstrates Steric and Electronic Substituent Effects in the Organic Chemistry Lab

et al. 2021

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“…Compared to traditional single-outcome procedures, the aforementioned variances allow more unique learning experiences to occur in the classroom and create a more synergistic relationship with the associated lecture presentation. ,,, An example of an MOE recently developed and implemented into the undergraduate organic instructional laboratory explores the oxidation of alcohols. This new MOE addresses the challenges previously mentioned and also specifically reinforces the utility of NMR spectroscopy by providing access to benchtop 1 H NMR technology to undergraduate students, thereby encouraging engagement and ownership of the experiment. ,,− Commonly used NMR instruments have high operation costs, requiring the use of cryogens and specially trained staff members. Since the advent of benchtop 1 H NMR technology, spectra of neat samples spiked with tetramethylsilane (TMS) are collected in a matter of seconds and processed within a few minutes using NMR processing software such as MestreNova or TopSpin.…”

Section: Multioutcome Experimentsmentioning

confidence: 90%

Developing and Implementing Multioutcome Experiments in Undergraduate Teaching Laboratories To Promote Student Ownership of the Experience: An Example Multioutcome Experiment for the Oxidation of Alcohols

2019

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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.

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“…There are many examples reported in this Journal of inquiry-based organic experiments where students can apply core organic theory, including the aldol reaction, , nucleophilic addition to carbonyls, E2 elimination, electrophilic aromatic substitution, the Wittig reaction, and metathesis. , There are also examples where whole or partial organic laboratory courses have become inquiry-based with positive outcomes for the development of scientific skills. − …”

Section: Introductionmentioning

confidence: 99%

Design and Delivery of Virtual Inquiry-Based Organic Chemistry Experiments

Mistry

Shahid

2021

J. Chem. Educ.

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Guided-inquiry experiments are an important tool for helping students develop scientific practices such as hypothesizing and problem solving. In organic chemistry, these types of experiments can help students learn how to connect the theory of the reaction to the observation and data to decide how the reaction is proceeding or if it needs adapting. Due to a reduction of in person teaching during the COVID-19 pandemic, we developed a set of virtual inquiry-based organic chemistry experiments where students make the same decisions as they would do with a hands-on inquiry experiment. Thus, these simulations allow students to learn similar problem-solving skills. In this paper, we provide details of the simulations and the educational outcomes when they were used to replace hands-on inquiry experiments. We also include suggestions for its use postpandemic.

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A Mixed-Aldol Condensation Reaction with Unknown Aldehydes and Ketones: Employing Modern Methods To Improve the Learning Process for Second-Year Undergraduate Organic Chemistry Students

Cited by 17 publications

References 7 publications

Aldol Condensation Reaction Rate Demonstrates Steric and Electronic Substituent Effects in the Organic Chemistry Lab

Aldol Condensation Reaction Rate Demonstrates Steric and Electronic Substituent Effects in the Organic Chemistry Lab

Developing and Implementing Multioutcome Experiments in Undergraduate Teaching Laboratories To Promote Student Ownership of the Experience: An Example Multioutcome Experiment for the Oxidation of Alcohols

Design and Delivery of Virtual Inquiry-Based Organic Chemistry Experiments

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