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20 th Biennial Conference on Chemical Education Indiana University, Bloomington, Indiana, July 27, 2008. Solving Qualitative Organic Problems with the Aid of an Automated Isotope-Pattern Analyzer. Ray A. Gross, Jr. Prince George’s Community College. Introduction. - PowerPoint PPT Presentation
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20th Biennial Conference onChemical Education
Indiana University, Bloomington, Indiana, July
27, 2008
Solving Qualitative Organic Problems with the Aid of an Automated Isotope-Pattern
Analyzer
Ray A. Gross, Jr.Prince George’s Community
College
Introduction
• Many aryl compounds contain small combinations of Br, Cl and S atoms.
• The Br, Cl, S stoichiometry of most of these compounds is revealed in their characteristic molecular-ion peaks in their low-resolution mass spectra
• An automated isotope-pattern analyzer has been developed that determines the A + 2 composition of these compounds.
Outline
• Three qual-organic problems will be solved with the aid of the IPA.
• The IPA will be demonstrated.
Problem 1
•
What is the Br, Cl, S composition?
Spectrum: Spectral Database for Organic Compounds, SDBS
Problem 1
•
What is the Br, Cl, S composition?
M = 288 (11.5%)M + 2 = 290 (8.5%)M + 4 = 292 (2.0%)
Spectrum: Spectral Database for Organic Compounds, SDBS
3,4-toluenedisulfonyl dichloride
SO2Cl
SO2Cl
Cl2S2
Problem 2Compound A: mp 82 oC
m/e %
194 49.4
195 10.4
196 47.0
197 5.8
198 16.1
199 1.2
200 1.6
201 0.1
Compound A: Cl3
75
3 Cl
105
194 - 180 = 14 = Me
= 180
Cl
Cl
Cl
Cl
Cl
Cl
mp ~ 82 oC
194
Compound A: 2,4,6-trichlorotoluene
Problem 3
Compound A (mp 38 oC)
Compound Bhydrolysis
m/e %244 26.0246 26.2248 9.1250 1.3
m/e %226 100.0228 64.9230 12.5
Compound A: Cl3S1
Compound B: Cl2S1
Compound A: 2,4-dichlorobenzenesulfonyl chloride
Compound A (mp 38 oC)
Compound Bhydrolysis
m/e %244 26.0
m/e %226 100.0
Cl3S1 Cl2S1
244 - 35 = 209; 209 + 17 = 226
Cl
75 35
Cl Cl S
35 35 32 = 212
244 - 212 = 32 = 2 oxygen atoms
Cl Cl
SO2Cl
mass = 244
SO2Cl
ClCl
mp ~ 38 oC
Conclusion
• The IPA is a useful tool for qualitative organic analysis.
• Finds A + 2 compositions for 21 combinations of Br, Cl and S.
J. Chem Educ., 2007 84, 987-991