A Discovery-Based Experiment Involving Rearrangement in the Conversion of Alcohols to Alkyl Halides

Kjonaas, Richard A.; Tucker, Ryand J. F.

doi:10.1021/ed085p100

Cited by 14 publications

(21 citation statements)

References 1 publication

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“…Subsequently, a mixture of 2chloropentane, 2-bromopentane, 3-chloropentane, and 3bromopentane in unequal ratios was observed in the reaction for both secondary alcohols. 8 To monitor this secondary to secondary carbocation rearrangement, either the instructor or the students could perform two simple labeling experiments on 3-pentanol.…”

Section: Secondary To Secondary Carbocation Rearrangement In the Reac...mentioning

confidence: 99%

New Look at the Competitive Nucleophilic Substitution Reaction in the Pentanol Series

et al. 2021

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Substitution reactions of alcohols are some of the simplest experiments performed in undergraduate organic chemistry laboratory settings. However, the use of gas chromatography (GC) as an analytical tool for these reactions can be at times laborious and time-consuming. In this work, 1-pentanol, 2-pentanol, 3-pentanol, and 2-methyl-2-butanol were reacted with a 50/50 mixture of ammonium chloride− ammonium bromide in water to yield the corresponding alkyl bromide and alkyl chloride mixtures. Aliquots of the reaction mixture were analyzed using proton nuclear magnetic resonance ( 1 H NMR) spectroscopy and verified by GC. Secondary to secondary carbocation rearrangements were observed in the nucleophilic substitution reactions of 2-and 3-pentanol yielding a mixture of 2-and 3-substituted alkyl halides, while the primary and tertiary alcohols yielded the expected products. Students were assessed on their observations and explanations with the majority of them able to identify the correct reasoning for the alkyl halides mixture formation. 1 H NMR spectroscopy provided an inexpensive and quicker method to analyze the mixture and expose the students to the secondary to secondary carbocation rearrangement in the nucleophilic substitution reaction in the pentanol series.

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Section: Secondary To Secondary Carbocation Rearrangement In the Reac...mentioning

confidence: 99%

New Look at the Competitive Nucleophilic Substitution Reaction in the Pentanol Series

et al. 2021

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“…While the use of H 2 SO 4 /NaBr for bromination of alcohols has been classically used in expository teaching laboratory experiments 35−37 and was later modified to the previously noted discovery-based approach, 7 the current experiment enhances former protocols in the following ways:…”

Section: ■ Overview Of Experimentsmentioning

confidence: 99%

“…To strengthen and reinforce the mechanistic principles underpinning organic reactions while solidifying NMR analysis skills, we have developed a discovery-based 4−6 bromination of isomeric alcohols experiment expanding on a previous report. 7 Discovery-based experiments (also sometimes called guided-inquiry 4,5 ) could be characterized as those that provide students with a tested procedure producing a predetermined, yet unspecified, outcome. During these experiments, therefore, the students must "discover" the experimental outcome once they have obtained the necessary data.…”

Section: ■ Introductionmentioning

confidence: 99%

Discovery-Based Bromination of Alcohols: An Organic Chemistry Experiment Supporting Spectroscopic Analysis and Mechanistic Reasoning

et al. 2021

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The bromination of six isomeric alcohols is adapted to a discovery-based organic chemistry laboratory experiment, whereby students are provided an alcohol starting material and are charged with determining the product or product mixture produced using relevant spectroscopic data. The experiment solidifies NMR analysis skills while reinforcing the mechanistic reasoning that supports the study of organic reactions. The laboratory is highly customizable and can be adapted to align with available instrumentation to best meet the needs of students, and it has been successfully implemented at three separate universities.

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“…35,36 Kjonaas and Tucker showed that the conversion of an alcohol to an alkyl halide undergoes a hydride shift in the formation of the product. 37 Field and coworkers investigated the conversion of an alkene to 1,2dichloro-1,1,2,2-tetraphenylethane. From that product, the reaction can proceed either of two ways: one way is to not undergo a shift in which case the product is an epoxide; in the other the product undergoes an aryl shift in which case the product is a ketone.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Two groups independently presented a valuable update to the classic dehydration of 2-methyl-cyclohexanol laboratory, including an examination of the formation of five previously unidentified products via carbocation rearrangements. The mechanisms include both hydride and alkyl shifts, including a ring contraction. , Kjonaas and Tucker showed that the conversion of an alcohol to an alkyl halide undergoes a hydride shift in the formation of the product . Field and co-workers investigated the conversion of an alkene to 1,2-dichloro-1,1,2,2-tetraphenylethane.…”

Section: Introductionmentioning

confidence: 99%

Expanding the Scope of an Electrophilic Aromatic Substitution Discovery Experiment Including Hydride and Methyl Shifts

et al. 2021

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Friedel–Crafts alkylation reactions using a curated set of alcohols provide students with the opportunity to combine the study of electrophilic aromatic substitution with carbocation rearrangements. In this experiment students may be presented with up to nine alcohols that yield six products, all synthesized under identical reaction conditions. They distinguish their products using a range of instrumental methods including infrared, 1H NMR, and 13C NMR spectroscopies, and mass spectrometry. Additional characterization is provided by the determination of melting point/mixed-melting point and gas chromatographic retention time. Students work in teams to assign structures to their individual reaction products; providing nine starting materials ensures minimal duplicates in a given laboratory section. As students interpret their data, some discover that a carbocation rearrangement occurred, resulting in isolation of only one product despite starting from a pair of isomeric reagents. This laboratory provides students with the opportunity to engage in a range of laboratory and problem-solving skills, and thus is designed to be performed toward the end of a two-semester organic chemistry sequence.

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A Discovery-Based Experiment Involving Rearrangement in the Conversion of Alcohols to Alkyl Halides

Cited by 14 publications

References 1 publication

New Look at the Competitive Nucleophilic Substitution Reaction in the Pentanol Series

New Look at the Competitive Nucleophilic Substitution Reaction in the Pentanol Series

Discovery-Based Bromination of Alcohols: An Organic Chemistry Experiment Supporting Spectroscopic Analysis and Mechanistic Reasoning

Expanding the Scope of an Electrophilic Aromatic Substitution Discovery Experiment Including Hydride and Methyl Shifts

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