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Organic Structure Elucidation

This document discusses resources available for structure elucidation of organic molecules at the Magnetic Resonance Research Center of the University of Notre Dame and gives brief recommendations.

Contents

• Samples

• Spectrometers

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Samples

Here are sample requirements for acquisition of necessary spectral data on Bruker 800 with a room-temperature probe (TXI).

1. Minimum advisable concentration = 5 mM

2. NMR tube volume:

• Normal tube = 0.6 ml
• Shigemi tube = 0.3 ml

3. How much compound in milligrams will you need?

[Weight of your compound, mg] =   [concentration, mM]  *  [molecular weight, g/mol] * [sample volume, ml] /1000

Example:

To make a sample of 650 Da compound in a Shigemi tube, I need to have  
5 mmol/L * 650 g/mol * 0.3 ml /1000  = 0.98 mg

4. The sample must be stable at room temperature for, at least, 24 hours.

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Spectrometers

As of 2/2/2022, we recommend

• proton detection: Bruker 800 MHz with a TXI probe
• carbon detection: Bruker 800 with a BBO probe or Bruker 500 or Varian 600 with broadband probes.
  NOTE: Data of similar quality may be obtained on Bruker 500 or Varian 600 but resolving closely spaced peaks of stereoisomers may be more difficult than at the 800 MHz.