ANALYTICAL CHEMISTRY - UNL



SPECIAL TOPICS IN ANALYTICAL CHEMISTRY

Introduction to NMR

CHEM 991A, Fall 2014

MWF 11:30-12:20, Rm 133/134 Hamilton Hall

A.) Instructor: Dr. Robert Powers

Office Labs

Address: 722 HaH 721-720 HaH

Phone: 472-3039 472-5316

Web site:

Office Hours: 10:30-11:30 am MWF or by Special Appointment.

I am in my office many other times during the week and am always willing to speak with you if you find me in or make an appointment.

B.) Required Items:

(i) Required Text:

J. W. Akitt & B. E. Mann, NMR and Chemistry: An Introduction to Modern NMR Spectroscopy, Stanley Thornes, 2000.

(ii) Highly Recommended:

Pretsch, E., Bühlmann, P., and Affolter, C., Structure Determination of Organic Compounds: Tables of Spectral Data, Springer-Verlag, 3rd ed., 2000

M. H. Levitt, Spin Dynamics – Basics of Nuclear Magnetic Resonance, Wiley, 2001.

(iii) Calculator for exams (TI-89 style or a simpler model)

C.) Coursework:

Students will have a midterm and final exam, three structural problems, and an oral presentation. The midterm will be held in the evening on the tentative date shown below. The final exam will be held at the time listed in the course schedule.

Midterm Exam: 100 pts (Fri., Oct 10th)

Final Exam: 100 pts (Tues., Dec. 16th)

Structure Problems (3) 150 pts (Fri., Dec. 12th)

Oral Presentation: 50 pts (Various)

Total: 400 pts

Answer keys for the problem sets and exams will be posted on BlackBoard after Fri., Dec. 12.

D.) Grading sale: A+=95%; A=90%; A-=85%; B+=80%; B=75%; B-=70%; C+=65%;

C=60%; C-=55%; D=50%; D-=45%; F=40%

E.) Calculators & Translators: Please restrict the calculators you bring to exams to a TI-89 style calculator or a simpler model. You only need basic math functions to complete the exam. Please do not bring programmable calculators or calculators that allow text entry.  Also, if you require a translator to assist in understanding the exam questions, please only bring a translator that is limited to a single word translation. Do not bring translators that allow large text entry or that can use WIFI and download text from the internet.

F.) Course Overview:

Nuclear magnetic resonance spectroscopy (NMR) is an important analytical method and an integral component of modern synthetic chemistry. NMR deals with understanding the composition, structure, dynamics and function of matter. NMR is routinely and widely used as the preferred technique to rapidly elucidate the chemical structure of most organic compounds. Consequently, NMR is one of the most routinely used analytical techniques. This course will provide an introduction to the theory and techniques of NMR spectroscopy with a particular application to the structure determination of organic compounds. The course will cover the basic theory of NMR that includes chemical shifts, coupling constants and relaxation. Topics will also include the application and analysis of two-dimensional NMR spectra to determine chemical structures. The lectures will also include discussions on the basic design and implementation of an NMR experiment or pulse sequence. This will include discussions on NMR instrumentations, RF pulses, experimental and processing parameters.

By becoming familiar with the basic principal and operation of NMR instrumentation, you will be able to make informed decisions and efficient use of the spectrometer in your own research projects. There are an abundant number of NMR methods that can be alternatively used to solve a given structural problem. Your efficieny and success at being able to solve a structural problem will be enhanced by becoming familiar with the range of available NMR experiments available to you. Also, by understanding the limitations in sensitivity, precision, and accuracy, and by understanding sample requirements and the capabilities of a specific NMR experiment, you will be able to choose the most appropriate method to apply to a specific problem. Also, by the understanding the proper operation, calibration, performance and experimental set-up, you will be able to properly utilize an NMR to correctly analyze a sample. In effect, you can maximize the quality of NMR spectra you obtain from an NMR spectrometer if the instrument is not treated like a “black-box”.

For each lecture topic there is a corresponding reading assignments. The reading assignments should be completed prior to each lecture and your participation in classroom discussions is expected. Successfully completing the reading and structure problem sets will increase your likelihood of doing well on the exams.

G.) Exams:

The midterm will take place on Oct. 10 at 6 pm in Hamilton Hall Rm. 133/134. The Final Exam will take place on Tues, Dec. 16 at 10 am in Hamilton Hall Rm. 133/134. The length of each exam will be two hours.

H.) Structure Problems:

A major component of the overall grade for this course will include the determination of the structure for three unknown organic compounds using realistic experimental NMR data obtained using the departmental NMR spectrometers. Each unknown organic compound will include the following data set: a) chemical formula, b) 1D 1H NMR spectra, c) 1D 13C NMR spectra, d) 2D 1H COSY, e) 2D 1H NOESY, f) 2D 1H-13C HMQC, g) 2D 1H-13C HMBC and h) 2D 1H-13C HSQC-TOCSY. The NMR data for the unknowns will be available in the NMR computer lab (832 HaH) with a guide for using the NMR software.

The structure problem sets will be randomly assigned to each student on the first day of class. The completed report for the structure determination of the organic unknowns will contain the following information: 1) Your name, 2) unknown number, and 3) chemical structure of the unknown. Your grade will be based on how close your predicted structure matches the true structure of the unknown. The final due date for the three structure problems is the beginning of class on Friday, Dec. 12th. Feel free to hand in completed problem sets any time before the due date. These problems sets will be graded quickly and the grades will be immediately posted on Blackboard. The answer keys will not be posted until after the due date.

Do Not Work Together To Solve the Structure Problem Sets.

Do Not Share Your Results With Other Students.

The goal is to develop your skills in analyzing NMR data to solve the structure of a compound, not to simply report the correct structure to obtain a high grade. It is in your best interest to work through these problems on your own. Any evidence that a student has not independently determined a structural solution for each unknown will result in a failing grade for the class.

Please use this as an opportunity to gain experience and training with the TopSpin NMR software. Please schedule a time to meet with Dr. Martha Morton (834B HaH, 472-6255) to receive basic training on running 2D NMR experiments on a Bruker console. Dr. Morton will set-up and distribute a Doodle poll to schedule training times. Students will receive training in groups of 3 to 4 on a first-come basis. Dr. Morton will also oversee scheduling and access to the NMR computer lab. The web address for the Research Instrument facility that contains online manuals and instrument scheduling is:

I.) Software Labs

The first three lectures following the course overview is dedicated to hands-on NMR software training with Dr. Martha Morton. The training will take place in the NMR computer lab (Rm. 832). Please report to Rm 832 instead of Rm. 133/134 on Aug 27-Sep. 3. The goal of the software labs is to provide you with the necessary practical skills to enable you to process and analyze the NMR datasets for the three structure problem sets. The software labs will enable you to complete the structure problem sets.

J.) Oral Presentation of an NMR Paper:

The overall grade in this course will include an oral presentation of a scientific article that either: (1) describes an NMR method (i.e., pulse sequence, software, or strategy) to determine the structure of an organic molecule or (2) describes the determination of the structure of an organic molecule or natural product that primarily used NMR. The presentations should be approximately 20 minutes in length, two students will present on a given day, and the presentations will occur during class over the final two weeks of the semester. Please send an electronic copy of the paper to the class before your presentation.

The goal of a method presentation is to educate your classmates in an NMR method that you have identified as being valuable or interesting for the investigation of organic compounds. Please note: the NMR method you choose to present CANNOT have been previously discussed in class. The goal of a structure presentation is to explain to the class, in detail, how NMR was used to determine the structure of a specific organic molecule or natural product. The presenter should go through all the NMR experiments and explain stepwise how the NMR spectra supports the final structure and/or excludes alternative structures. Please note: the chosen structure should be particularly challenging requiring multiple NMR experiments.

Each presentation will be worth 50 points. Importantly, the grade for your presentation will be a combination of my assessment and the assessment from the other students in the course. Each student will have a defined number of As, Bs, and Cs to use to grade the presenter. In this manner a student cannot give all As or all Cs. Based on the number of students enrolled, each student will be allocated approximately 30% As, 55% Bs, and 15% Cs per round of oral presentations. The default assigned grade is a B, so each student will also have to justify assigning either an A or a C to a particular presenter. All the assessments will be averaged together to determine the number of points based on the following grading scheme:

Average Assessed Grade: A to A-: 50pts, B+: 45pts, B to B-: 40pts, C+: 35pts, C: 30pts.

Students should consider these issues when assessing a presenter: (1) How well did the presenter understand the material? (2) How clearly did the presenter discuss the material? (3) Was the chosen paper of general interest and relevant to organic chemistry or natural product chemistry? (4) Was NMR a major focus of the paper? (5) How well did the presenter answer questions? (6) Did the paper lead to an interesting discussion?

A few recommended sources of research articles: JACS, J. Mag Res., Concepts in Magnetic Resonance, Progress in Nuclear Magnetic Resonance Spectroscopy, Anal. Chem., J. Med. Chem. PNAS, Journal of Organic Chemistry, Organic Letters, Angewandte Chemie, and Angewandte Chemie International Edition, ChemMedChem, and Natural Products Reports.

I.) Services for Students with Disabilities

American Disabilities Act: Students with disabilities are encouraged to contact the instructor for a confidential discussion of their individual needs for academic accommodation. It is the policy of the University of Nebraska-Lincoln to provide flexible and individualized accommodation to students with documented disabilities that may affect their ability to fully participate in course activities or to meet course requirements. To receive accommodation services, students must be registered with the Services for Students with Disabilities (SSD) office, 132 Canfield Administration, 472-3787 voice or TTY.

Lecture Topics

CHEM 991A, Fall 2014

Date Chapter Topic

I. Basic NMR Theory

Aug 25 Course Overview & Scheduling

Aug 27 Software Lab

Aug 29 Software Lab

Sep 3 Software Lab

Sep 5 Chap 1 Introduction to NMR Theory

Sep 8 Chap 1

Sep 10 Chap 1

Sep 12 Chap 5 Obtaining an NMR Spectrum

Sep 15 Chap 5

Sep 17 Chap 5

Sep 19 Chap 5

Sep 22 Chap 5

Sep 24 Chap 2 Chemical Shifts (δ)

Sep 26 Chap 2

Sep 29 Chap 2

Oct 1 Chap 2

Oct 3 Chap 3 Coupling Constants (J)

Oct 6 Chap 3

Oct 8 Chap 3

Oct 10 Midterm Exam

Oct 13 Chap 6 NMR Pulses

Oct 15 Chap 6

II. One and Two Dimensional NMR

Oct 17 Chap 8 1D NMR

Oct 20 to Oct 21 Fall Break

Oct 22 Chap 8

Oct 24 Chap 8

Oct 27 Chap 8

Oct 29 Chap 9 2D NMR

Oct 31 Chap 9

Nov 3 Chap 9

Nov 5 Chap 9

Nov 7 Examples of Spectral Interpretations

III. NMR Dynamics

Nov 10 Chap 4 & 7 Relaxation & Exchange

Nov 12 Chap 4 & 7

Nov 14 Chap 4 & 7

Nov 17 Chap 4 & 7

IV. Solid State NMR

Nov 19 Chap 11 Solid State NMR

Nov 21 Chap 11

V. Presentations of NMR Papers

Nov 24 Oral Presentations

Nov 26 to Nov 28 Thanksgiving Break

Dec 1 Oral Presentations

Dec 3 Oral Presentations

Dec 5 Oral Presentations

Dec 8 Oral Presentations

Dec 10 Oral Presentations

Dec 12 Review Structure Problem Sets Due

Dec 16 Final Exam

Topic Chapters in NMR & Chemistry.

I. BASIC NMR Theory

I. Introduction to NMR Theory 1

a. Quantum and classical description

II. Obtaining an NMR Spectra 5

a. Data acquisition

b. Data processing

c. instrumentation

III. Chemical Shifts (δ) 2

a. Select examples of chemical shift trends

b. Predicting chemical shifts

IV. Coupling Constants (J) 3

a. Simulation of second-order spin systems

II. One and Two Dimensional NMR

I. NMR Pulses 6

II. 1D NMR 8

a. Specific experiment examples

1. NOE

2. J modulation

3. INEPT

4. DEPT

5. INADEQUATE

III. 2D NMR 9

a. Theory

b. Specific experiment examples

1. COSY

2. TOCSY

3. NOESY

4. HMQC

5. HMBC

IV. Examples of Spectral Interpretation 8

III. NMR Dynamics

I. Relaxation 4

a. T1, T2

b. Dipole-Dipole

c. CSA

d. Quadrupolar relaxation

II. Exchange 7

a. NMR time scale

IV. Solid State NMR 11

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