{"title":"Rotational Barriers in Push-Pull Ethylenes: An Advanced Physical-Organic Project Including 2D EXSY and Computational Chemistry","authors":"Tammy J. Dwyer, Julia E. Norman, Paul G. Jasien","doi":"10.1021/ed075p1635","DOIUrl":null,"url":null,"abstract":"<p >An integrated upper-division physical-organic experiment for chemistry majors has been developed. It involves the determination and mechanistic interpretation of the C=C and C-N rotational barriers in a push-pull ethylene. In the course of the experiment students will synthesize an organic compound, acquire variable temperature 1D and 2D NMR spectra, and use computational quantum chemistry to gain a deeper understanding of the unique electronic features of the molecule. Low temperature 2D EXchange SpectroscopY (EXSY) is used to quantitate the rotational barriers in a series of solvents. The quantum mechanical calculations provide a means to compare the properties of the push-pull ethylene with a similar non-push-pull system. Analysis of the experimental and theoretical results leads to a nearly complete picture of how substituent effects can influence bond lengths, rotational barriers, and the electronic distribution in these ethylenes.</p>","PeriodicalId":43,"journal":{"name":"Journal of Chemical Education","volume":"75 12","pages":"1635"},"PeriodicalIF":2.5000,"publicationDate":"1998-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1021/ed075p1635","citationCount":"15","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Chemical Education","FirstCategoryId":"92","ListUrlMain":"https://pubs.acs.org/doi/10.1021/ed075p1635","RegionNum":3,"RegionCategory":"教育学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 15
Abstract
An integrated upper-division physical-organic experiment for chemistry majors has been developed. It involves the determination and mechanistic interpretation of the C=C and C-N rotational barriers in a push-pull ethylene. In the course of the experiment students will synthesize an organic compound, acquire variable temperature 1D and 2D NMR spectra, and use computational quantum chemistry to gain a deeper understanding of the unique electronic features of the molecule. Low temperature 2D EXchange SpectroscopY (EXSY) is used to quantitate the rotational barriers in a series of solvents. The quantum mechanical calculations provide a means to compare the properties of the push-pull ethylene with a similar non-push-pull system. Analysis of the experimental and theoretical results leads to a nearly complete picture of how substituent effects can influence bond lengths, rotational barriers, and the electronic distribution in these ethylenes.
期刊介绍：
The Journal of Chemical Education is the official journal of the Division of Chemical Education of the American Chemical Society, co-published with the American Chemical Society Publications Division. Launched in 1924, the Journal of Chemical Education is the world’s premier chemical education journal. The Journal publishes peer-reviewed articles and related information as a resource to those in the field of chemical education and to those institutions that serve them. JCE typically addresses chemical content, activities, laboratory experiments, instructional methods, and pedagogies. The Journal serves as a means of communication among people across the world who are interested in the teaching and learning of chemistry. This includes instructors of chemistry from middle school through graduate school, professional staff who support these teaching activities, as well as some scientists in commerce, industry, and government.
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