Mass SpectrometryPROBLEM SET I

1
Mass Spectrometry PROBLEM SET I

• Go to the Spectral Database for Organic Compounds
• http//www.aist.go.jp/RIODB/SDBS/cgi-bin/direct_fr
  ame_top.cgi?langeng
• and analyze the mass spectrum for the compounds
  on the following slide.
• For each spectrum, comment on the M peak, and
  determine the fragments that produce each of the
  major peaks (starting with the base peak). For
  spectra with more than 3 major peaks, try to do
  at least ¾ of the major peaks.
• Remember you may use the simplified mechanisms
  for retro-Diels-Alder and the McLafferty
  rearrangment, so long as the fragments you
  generate are correct.
• On the database, actual peak lists are given,
  where you may be able to obtain the M1 peak
  intensity. See if it properly predicts the
  number of carbons in the spectrum (you can set
  the threshold lower than 1)
• Use the rule of 13 to ensure you are producing
  the actual molecular formula as one of the
  possibilities as well as the proper HDI

2
Mass Spectrometry PROBLEM SET I

• Here are the compounds for set 2
• 3-heptanone ethyl propionate hexanoic acid
• valeramide hexanal 2-methylbutanal (M ion
  suspect)
• N-methylbutylamine 2-methylbutylamine N,N-dimethyl
  propionamide
• pivalonitrile m-nitrophenol m-bromochlorobenzen
  e

3
Mass Spectrometry PROBLEM SET I

• For the following compounds, determine the best
  possible structure that gives each of the
  following mass spectra
• M 134 (37.2), M1 (3.7)

4
Mass Spectrometry PROBLEM SET I

• For the following compounds, determine the best
  possible structure that gives each of the
  following mass spectra
• M 158 (0.2) M1 non-existent

5
Mass Spectrometry PROBLEM SET I

• For the following compounds, determine the best
  possible structure that gives each of the
  following mass spectra
• M 128 (0.5), M1 (0.1)

6
Mass Spectrometry PROBLEM SET I

• For the following compounds, determine the best
  possible structure that gives each of the
  following mass spectra
• M 136 (74.6), M1 (6.4)

7
Mass Spectrometry PROBLEM SET I

• For the following compounds, determine the best
  possible structure that gives each of the
  following mass spectra
• M 107 (60.1), M1 (4.9)

8
Mass Spectrometry PROBLEM SET I

• For the following compounds, determine the best
  possible structure that gives each of the
  following mass spectra
• M 87 (2.9), M1 (0.2)

9
Mass Spectrometry PROBLEM SET I

• For the following compounds, determine the best
  possible structure that gives each of the
  following mass spectra
• M 190 (75.3), M1 (5.3), M2 (100), M4 (23.9)

10
Mass Spectrometry PROBLEM SET I

• For the following compounds, determine the best
  possible structure that gives each of the
  following mass spectra
• M 100 (8.0), M1 (0.5)

11
Mass Spectrometry PROBLEM SET I

• For the following compounds, determine the best
  possible structure that gives each of the
  following mass spectra
• M 73 (100), M1 (3.9)

12
Mass Spectrometry PROBLEM SET I

• For the following compounds, determine the best
  possible structure that gives each of the
  following mass spectra
• M 117 (100.0), M1 (9.2)

13
Mass Spectrometry PROBLEM SET I

• Answers
• 3-methylacetophenone
• pentyl butyrate
• octanal
• m-toluic acid
• benzylamine
• iso-pentylamine
• p-bromochlorobenzene
• 2-hexanone
• N,N-dimethylformamide
• p-tolunitrile