Examine data relating to the structure and complexity of compounds, including mass, infrared and NMR spectra, in this workshop lesson plan for 16–18 year olds

In this session, students take part in a workshop, combining mass spectra, infrared spectra and NMR spectra. They are provided with data for seven different compounds of increasing complexity.

These activities will sit well within a series on structure determination. Students will need to have been introduced to the three basic techniques and have some knowledge of organic chemistry. The activities could be presented as a revision guide as well as being used to support the development of understanding.

Learning objectives

Students will recognise that:

  • A combination of data from three main techniques provides clues to structure.
  • Data from MS, IR and NMR can be used to determine structure.
  • Data are not always clear cut and an overall view is needed to work out structures.

Sequence of activities

Introduction

Share the learning objectives by explaining that ’The great nandrolone mystery’ provides a context for studying structures.

Activity: The great nandrolone mystery

  1. Distribute ’The great nandrolone mystery’ and the ’Background information’ sheets to each student.
  2. Organise the students into small groups. Circulate and support as they:
    • Work through the activity.
    • Prepare responses to feedback.

Plenary 1

In a plenary:

  1. Invite responses to the questions.
  2. Review the summaries of advice to the Association of Tennis Professionals.
  3. Using questions, introduce the notion that drug testing is just one use for analytical techniques. For example:
    • What other techniques may help resolve the nandrolone mystery?
    • What other uses may structure determination methods have?

Activity: Structure determination

  1. Introduce the next activity to the students, explaining that they will use a range of techniques in structure determination.
    • Note: decide if groups should work on one compound each, or work through the series of compounds. They are arranged in order of difficulty from 1 to 7, so differentiation by task is possible. Students may also carry out the task individually if preferred.
  2. Give each student the ‘Determining the structure of compounds’ worksheet.
  3. Give support while the students work through the spectra to arrive at the results.

Plenary 2

Use a final plenary to:

  1. Review answers to the spectra.
  2. Check for understanding about using a combination of spectra to arrive at a conclusion.

Commentary

The introductory task provides the opportunity for information analysis and comprehension. Students will need to synthesise, share and question ideas in answering the questions and writing the summary. The summaries will indicate if students have understood the key points, leading to a discussion of the value of analytical techniques. The structure determination activity requires synthesis of complex data with the opportunity for groups or individuals to receive teacher feedback.

Answers

The great nandrolone mystery

  1. An anabolic steroid also known as Deca‑Durabolin; a dietary supplement for building body mass.
  2. a. and b. – See structures in text.
  3. Oxidise the –OH group, reduce the =O group.
  4. Use of HRMS and HPLC.
  5. Building body mass artificially by drug use is against the rules of sport.
  6. The substance must be detected at very low levels (2 ng/ml).
  7. 19 norandrosterone is C18H29O2 molecular ion peak at 277, others are:
    • 241 loss of =O, -OH and 2 other Hs.
    • 201 loss of 5-C ring (C5O = 76).
    • 185 loss of 6-C ring (C6H4O = 92).
    • 145 molecule splits (loss of C9H8O = 132).
    • other corresponding peaks at 132, 92, 76.
  8. High levels can be found due to ‘natural causes’ (see text).
  9. To be resolved by discussion.

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