A Method for Analyzing A + 2 Isotope Patterns for Use in Undergraduate Organic Courses

Ray A. Gross Jr.
Department of Physical Sciences and Engineering, Prince George''s Community College, Largo, MD 20774
J. Chem. Educ., 2007, 84 (6), p 987
DOI: 10.1021/ed084p987
Publication Date (Web): June 1, 2007

Abstract

A new method for analyzing the characteristic molecular-ion peak intensities found in the low-resolution mass spectra of compounds that contain small numbers of bromine, chlorine, and sulfur atoms has been developed. The method determines the subscripts of Br, Cl, and S in the molecular formulas of compounds that contain these atoms. The method depends on the intensity of each significant molecular-ion peak falling within a predictable range of values relative to the intensity of the parent peak. The use of a range of values sets this method apart from earlier methods. This method has a ninety-eight percent accuracy record for the determination of 21 different combinations of Br, Cl, and S atoms when the intensity of the parent peak is more than 3.5%. The intensity ratios for these 21 combinations were placed on a spreadsheet, producing an isotope-pattern analyzer designed specifically for use in organic qualitative analysis at the undergraduate level. The method affords students and instructors a useful tool for rapidly assessing the Br, Cl, S stoichiometry of an unknown from its mass spectrum.

Keywords (Audience):

Upper-Division Undergraduate

Keywords (Domain):

Organic Chemistry

Keywords (Pedagogy):

Computer-Based Learning

Keywords (Subject):

Bromine

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History

  • Received: August 03, 2009

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