A Teaching Experiment to Elucidate a Cation-π Effect in an Alkyne Cycloaddition Reaction and Illustrate Hypothesis Driven Design of Experiments.
A Teaching Experiment to Elucidate a Cation-π Effect in an Alkyne Cycloaddition Reaction and Illustrate Hypothesis Driven Design of Experiments.
复制标题
阐明炔环加成反应中的阳离子效应并说明假设驱动的实验设计的教学实验。
DOI：
10.1021/acs.jchemed.6b00318
复制
发表时间：
2017
影响因子：
3
通讯作者：
Lepore,SalvatoreD
中科院分区：
文献类型：
--
作者：
StGermain,ElijahJ;Horowitz,AndrewS;Rucco,Dominic;Rezler,EvonneM;Lepore,SalvatoreD
描述了一个有机化学实验，该实验基于最近的研究来阐明四烷基铵阳离子和炔丙基肼之间的新型阳离子−π相互作用。这种非键相互作用是氨催化的氮分子内环加成到炔丙基底物的C-C三键的末端碳的机制的关键组成部分。本教学实验采用反应实验和控制实验来验证两种不同的机制假说。具体地，在均相条件下用可溶性碱（苯酚钠）在存在和不存在四丁基溴化铵的情况下进行环化反应。学生观察到添加的铵盐加速了反应。然后，鼓励他们发展一个可验证的假设，铵盐在环化机制中的作用：典型的相转移或其他。然后使用IR光谱直接观察由于阳离子-π相互作用导致的炔伸缩模式的剂量依赖性位移。在这个实验中，本科生“研究人员”能够在当代系统上实践科学方法，并看到数据是如何生成和解释的，以在实验室环境中模拟真实和当前研究的方式在竞争性假设之间进行裁决。这个实验设计进行了测试的学生就读于介绍本科有机化学实验室。
An organic chemistry experiment is described that is based on recent research to elucidate a novel cation−π interaction between tetraalkammonium cations and propargyl hydrazines. This nonbonded interaction is a key component of the mechanism of ammonium-catalyzed intramolecular cycloaddition of nitrogen to the terminal carbon of a C–C triple bond of the propargyl substrate. In this teaching experiment, reactions and control experiments are employed to demonstrate the testing of two alternative mechanistic hypotheses. Specifically, cyclization reactions are performed with a soluble base (sodium phenoxide) with and without tetrabutylammonium bromide under homogeneous conditions. Students observe that the added ammonium salt accelerates the reaction. They are then encouraged to develop a testable hypothesis for the role of the ammonium salt in the cyclization mechanism: typical phase transfer or other. IR spectroscopy is then used to directly observe a dose dependent shift of the alkyne stretching mode due to a cation−π interaction. In this experiment, undergraduate “researchers” were able to practice the scientific method on a contemporary system and see how data are generated and interpreted to adjudicate between rival hypotheses in a way that emulates authentic and current research in a lab setting. This experimental design was tested on students enrolled in the introductory undergraduate organic chemistry lab.
影响因子：
--
作者：
R. Bertermann;H. Braunschweig;P. Constantinidis;Theresa Dellermann;Rian D. Dewhurst;W. Ewing;I. Fischer;T. Kramer;J. Mies;A. K. Phukan;A. Vargas
通讯作者：
R. Bertermann;H. Braunschweig;P. Constantinidis;Theresa Dellermann;Rian D. Dewhurst;W. Ewing;I. Fischer;T. Kramer;J. Mies;A. K. Phukan;A. Vargas
DOI：
10.1039/c5cc08641h
发表时间：
2016-02-07
期刊：
Chemical communications (Cambridge, England)
影响因子：
--
作者：
Nagy E;St Germain E;Cosme P;Maity P;Terentis AC;Lepore SD
通讯作者：
Lepore SD
影响因子：
3
作者：
Cox, JR
通讯作者：
Cox, JR