Lab V: Part 3 of 3-Part Dual Unknown Lab & GC/MS Workshop

Pre-Lab Work

Reading Assignment:

1. Mass Spectrometry:
   Hornback, pp 617-633.
2. Mass Spectrometry:
   Appendix for GC/MS only & Mohrig, Technique 20.1-20.2, & 20.5, pp. 341-349, 353-358.
   
   

Introduction

In lab, we will look at how to decipher information received from the GC/MS instrument.

Experimental Work
Objectives:

• To use the GC/MS information from the products of nucleophilic substitution reactions to get a better general understanding of how to analyze mass spectra.
  
• To use the MS data for your 2 unknowns to aid in the elucidation of your unknown compounds.
• To test for the presence of halide using the Beilstein Test.
  
• To perform the Beilstein Test for Halides on your 2 unknowns.

Experimental Procedure

After the GC-MS Workshop, you will be supplied with your unknown's MS spectrum and a list of possible compounds for your unknowns. Before leaving lab, you and your partner should make a cursory identification of your dual unknowns using the MS data and any previous data on your two unknowns.

Beilstein Test
Follow the procedure described in the Appendix.

Test 1-butanol, one of the chlorides or bromides provided as standards, and your unknowns from your Dual Unknown lab. Record your results in your notebook.

Which halogens give a positive Beilstein Test?

What causes the green flame in a positive Beilstein Test?

Post-Lab Work
1. What new information do you have about your unknowns from today's lab?

2. Does your new information substantiate the data from previous Dual Unknown labs?

3. Identify your two unknowns.

4. Complete the GC-MS worksheet(s) given to your in the GC-MS Workshop.