Introducing 2D NMR Spectroscopy to Second-Year Undergraduate Chemistry Majors Using a Building-Up Approach

Abstract

2D NMR spectroscopy techniques are introduced to second-year undergraduate organic chemistry students using a 3 h classroom activity. By first studying simple organic molecules, students are able to build up to solve more complex structures. This classroom activity first utilizes an instructor-guided problem-solving session focused on simple organic molecules (N,N′-dimethylethylene diamine, N,N-dimethylethylene diamine, and 3-(dimethylamino)-1-propylamine). Students then work together in teams to assign a more structurally complex molecule (2,4-dimethylphenol or 2,4-di-tert-butylphenol) using both 1D (1H, 13C, and DEPT-135) and 2D (COSY, HSQC, and HMBC) NMR spectra. By teaching second-year undergraduate students 2D NMR spectroscopy, the techniques are easily revisited in advanced undergraduate courses.

Distinguishing Vinylic and Aromatic 1H NMR Signals Using Selectively Deuterated Chalcones

“…Previous experiments reported in this Journal include the intentional conversion of C–H bonds to C–D bonds for the purposes of unambiguously assigning NMR signals to particular resonances. , Also, for many molecules it may be possible to assign NMR signals using well-established two-dimensional NMR techniques . There is a trade-off, of course, in the pedagogic value of each approach: deuteration can be expensive and time-consuming, and the introduction of two-dimensional NMR techniques requires the development of expertise that may or may not be reinforced later in the course or major.…”

“…25,26 Also, for many molecules it may be possible to assign NMR signals using well-established two-dimensional NMR techniques. 27 There is a trade-off, of course, in the pedagogic value of each approach: deuteration can be expensive and time-consuming, and the introduction of two-dimensional NMR techniques requires the development of expertise that may or may not be reinforced later in the course or major. There is support for both approaches, and instructors must select the approach that works best considering their course goals.…”

Carbohydrate Characterization through Multidimensional NMR: An Undergraduate Organic Laboratory Experiment

“…8,9 A building-up approach for small molecule NMR identification with two-dimensional spectra has been provided by Anderson-Wile. 10 This method leads to carbohydrates, as they are often taught toward the end of the second organic semester, and can be potential culminating examples in compound identification to move students confidently forward to advanced organic courses and/or research posts.…”

“…The 1 H NMR spectrum of a carbohydrate can be intimidating to a second-year undergraduate, but with a multidimensional spectrum, the compound’s structure can become conclusive. With the continued push for institutions to teach multipulse or multidimensional NMR spectroscopy at the second-year undergraduate organic level, more experiments are beginning to stress or include multidimensional spectra as helpful additions. , A building-up approach for small molecule NMR identification with two-dimensional spectra has been provided by Anderson-Wile . This method leads to carbohydrates, as they are often taught toward the end of the second organic semester, and can be potential culminating examples in compound identification to move students confidently forward to advanced organic courses and/or research posts.…”

Illustrating Elementary NMR Concepts through Simple Interactive Python Programs

“…5−9 However, these are most useful for advanced researchers in the field and/or those who have a good handle on the programming language; in addition, they are expensive and/ or noninteractive. Physical chemistry laboratory and computational exercises describing the fundamental aspects of pulsed NMR 10,11 and detection, 12,13 computation of NMR spectra and parameters, 14−16 study of conformational equilibria, 17 and theoretical aspects of product operator formalism, 18 the vector approach, 19 and multidimensional NMR, 20 etc., have been successfully implemented in the undergraduate/graduate curriculum.…”