Exercises with Shift Prediction, Spectrum Prediction, and NMR Data software.

Introduction

All these programs include drawing routines. After drawing the structure, the program will calculate the chemical shifts. These calculations are based on relatively large spectral databases and give good results for compounds similar to those in the database. In general, the results are better than found when calculating shifts by hand. However, be aware that these are predicted chemical shifts. Real results may vary.

ACD/CNMR

  1. Draw a structure using the element tools on the left side of the screen. The program adds H's to fill valence. Click on a bond to change to a double bond.

  2. After the structure is complete click on the recycle symbol to clean up the structure.

  3. Alternatively you may select the compound from the database by selecting the dictionary in the top right.

  4. Click on the CNMR Spectrum button at the bottom of the page.

  5. Hold the cursor over a peak or over a carbon in the structure.

  6. Click on the buttons across the top to simulate: Coupled Spectrum, J-Modulated Spectrum (APT), and other features.

  7. Select a solvent, change the sample concentration, and change the spectrometer frequency.

ACD/HNMR

  1. Draw a structure using the element tools on the left side of the screen. The program adds H's to fill valence. Click on a bond to change to a double bond.

  2. After the structure is complete click on the recycle symbol to clean up the structure.

  3. Alternatively you may select the compound from the database by selecting the dictionary in the top right.

  4. Click on the Calculate Spectrum button at the bottom of the page.

  5. Hold the cursor over a peak in the spectrum or over the structure.

  6. Click on the "Double Resonance" button at the top center to select a peak for selective homonuclear decoupling. Return by selecting (Spectrum|1)

  7. Click on "Show Integral Curve" button at the top center.

A Spectrum of Spectra and A Spectrum of Spectral Problems

These files are distributed on two CD-ROM's. A Spectrum of Spectra contains 164 compounds. A Spectrum of Spectral Problems includes 200 unknowns (grouped by difficulty). If you are using a computer with a CD-ROM drive you may look at the spectra on the CD-ROM. I have developed a web based front end for this software. To look at this, open Netscape and open the appropriate bookmark.

Interpreted NMR Spectra

This set of spectra from Widener University is available on the Web. Experiments include H-1, selective homonuclear decoupling, C-13, coupled C-13, gated decoupling, inverse gated decoupling, DEPT, APT, COSY, HETCOR, NOESY, and T1 Inversion Recovery. You may view a local copy that is loaded on the hard drive by opening Netscape and opening the appropriate bookmark. If you have access to the Internet, go to: http://science.widener.edu/svb/nmr/data_1.html

NMR Spectra of known compounds

This is a set of NMR data that includes H-1, C-13, DEPT 45, DEPT 90, DEPT 135, COSY, and Hetcor spectra. The data are available as FID and as spectra. If you would like to view some of this data, I have brought the files on a zip disk. If you have access to the Internet, go to: http://science.widener.edu/svb/nmr/data_2.html

NMR Spectra of unknown compounds

This is a set of data for 20 compounds that includes Elemental Composition, Mass Spectrum, H-1 NMR, and C-13 NMR. The NMR data are available as FID. If you would like to view some of this data, I have the files on a zip disk. If you have access to the Internet, go to: http://science.widener.edu/~svanbram/chem465/htmldocs/unknowns.html

SpecTool

Spectool is a series of Hypercards containing data that is useful for interpreting NMR Spectra. You navigate through the cards much like a web browser. Small popup cards on the side are available to help with navigation.

The program provides information about Mass Spectrometry, C-13 NMR, H-1 NMR, IR, and UV. This data is divided into data, tools, ranges, spectra, and spectral library.

Operation of the program is relatively straight forward. Just take a look and see what is available. If you get lost, use the navigation palette on the side to return to the top menu.

gNMR

A Tutorial is available from Cherwell Scientific. This privides a very through overview of the program.

C-13 NMR Module

  1. Load ChemWindow

  2. Draw a structure

  3. Select the structure

  4. Calculate the C-13 Shifts (Other|Calculate C-13 NMR)

NMR Analyzer

  1. Simulate Proton NMR of ethanol
    1. Run Macro for creating spin system (File|Auto)

    2. Enter information

    3. Enter Number of Spins: (6)

    4. Enter Chemical Shift for each nuclei
      1. OH 5.0 ppm
      2. CH2 3.7 ppm (Enter twice)
      3. CH3 1.2 ppm (Enter three times)

    5. Enter Coupling Constants in appropriate locations in matrix (2-4, 2-4, 2-6, 3-4, 3-5, 3-6). 8 Hz.

    6. Additional Signals (None for this system)

    7. Calculate

    8. Display Spectrum

    9. Set Spectrum parameters for Lorentzian plot and change display range if appropriate.

    10. Change Spectrometer Frequency

    11. Recalculate spectrum (Calculations|Generate Basis), (Calculations|Generate Hamiltonian), (Calculations|Diagonalize), (Calculations|Calculate).

    12. Display New Spectrum (Display|Spectrum)

    13. To zoom go back to (Display|Spectrum) and change Minimum Shift or Maximum Shift.

  2. Simulate 2-methyl-1-propanol Since this system has more than 7 spins, NMR Analyzer can not calculate second order interactions for the coupling. The first order spectrum may be displayed using the "Additional Signals" feature.
    1. Clear the previous data (File|New)

    2. Enter the signals (Parameters|Additional Signals)

      Shift Multiplicity J (Hz) H's
      3.4 doublet 8 2
      2.1 singlet 0 1
      1.7 heptuplet 8 1
      0.9 doublet 8 6

    3. Calculate

    4. Display Spectrum

    5. Change Spectrometer Frequency, Calculate, & Display

  3. Simulate Crotonaldehyde (Page 4-16 in lecture notes) Crotonaldehyde has a relatively complex splitting pattern. Since there are only 4 spins in this system, NMR Analyzer can calculate the second order interactions.
    1. Clear the previous data (File|New)

    2. Enter the following spin system (File|Auto)

      Proton Shift Multiplicity a b c d
      a2.0 3 5.0 1.6
      b6.9 1 5.0 15.0 0.4
      c6.0 1 1.6 15.0 7.6
      d7.6 1 0.4 7.6

    3. Change Frequency, Recalculate, and Display.

This page is maintained by
Scott Van Bramer
Department of Chemistry
Widener University
Chester, PA 19013

Please send any comments, corrections, or suggestions to svanbram@science.widener.edu.

This page has been accessed times since 1/5 /96 .
Last Updated Monday, May 26, 1997 11:53:55.