McLafferty

F.W McLafferty, R.H. Hertel, Org. Mass Spectrom. 1994, 8, 690-702. Probability-based matching of mass spectra. 

Several chapters in this book are based on articles that appeared in American Laboratory from 1981 to 1988. I wish to acknowledge my coauthors of these papers, F. J. McLafferty, W. Gratzer, and B. P. Angelis. I wish to thank the editors of American Laboratory, especially Brian Howard, for permission to quote extensively from those articles. 

Laitinen, H. A. Ewing, G. (eds). A History of Analytical Chemistry. The Division of Analytical Chemistry of the American Chemical Society Washington, D.C., 1972. McLafferty, E. W. Analytical Chemistry Historic and Modern, Acc. Chem. Res. 1990, 23, 63-64. 

McLafferty, F. W. Analytical Chemistry Historic and Modern, Acc Chem Res 1990,23, 63-64. 

McFadden, W.H., Techniques of Combined Gas Chromatography/Mass Spectrometry, Wiley, New York, 1973. McLafferty, F.W., Tandem Mass Spectrometry, Wiley, New York, 1983. 

McLafferty, F.W, Interpretation of Mass Spectra, University Science Books, 1996. 

Stauffer, D.B. and McLafferty, F.W., The Wiley/NBS Registry of Mass Spectral Data, Wiley Interscience, New York, 1989. 

E. W. McLafferty, ed.. Tandem Mass Spectromety,]ohn Wiley Sons, Inc., New York, 1983. 

The McLafferty rearrangement, as it is known, is useful for structure identification. For example, the mass spectmm of 2-methylbutanal shows a peak at m/e 58, while that of 3-methylbutanal shows a peak at m/e 44. 

Fred Warren McLafferty (1923-) was born in Evanston, Illinois, and received his Ph.D. in 1950 at Cornell University. He was a scientist atthe Dow Chemical Company from 1950to 1964 before becoming professor of chemistry at Purdue University. In 1968, he returned tD Cornell University as professor. 

In addition to fragmentation by the McLafferty rearrangement, aldehydes and ketones also undergo cleavage of the bond between the carbonyl group and the a carbon, a so-called a cleavage. Alpha cleavage yields a neutral radical and a resonance-stabilized acyl cation. 

Figure 19.19 Mass spectr um of 5-methyl-2-hexanone. The peak at m/z = 58 is due to McLafferty rearrangement. The abundant peak at mlz = 43 is due to ct cleavage at the more highly substituted side of the carbonyl group. Note that the peak due to the molecular ion is very small.

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