Knowledgebase

Online Chemistry Labs | Learning Objectives

Background:

This experiment allows students to determine the structure of four different sulfur-fluorine compounds using 19F-NMR. NMR is introduced as an instrumental technique which allows the chemist to determine how many different types of fluorine ligands are bonded to the central sulfur, as well as the relative number of each type. The principles of the NMR instrument are not discussed in any detail, and no knowledge of the NMR phenomenon is required. The student fills an NMR tube with each of the four compounds and obtains the spectra. For each compound, the student is presented alternative possible structures to consider and is asked to determine which is consistent with the spectrum obtained.

NMR 

Learning Objectives:

  1. Become familiar with the ability of 19F-NMR to determine how many different F-environments are present and the relative number of each type of fluorine in a compound.
  2. Learn how to interpret simple NMR spectra that contain only one or two different peaks in simple intensity ratios.
  3. Use the intensity ratio and number of peaks to select a structure that is consistent with the spectrum obtained. 
  4. Predict from a molecular structure whether a given fluorine has the same environment as another.