Chemical Education Today
Mechanisms in Motion— Organic Chemistry Animations v 1.5 Bruce H. Lipshutz, Exeter Multimedia; Jones and Bartlett: Sudbury, MA, 1996 (Macintosh), 1997 (Windows). $395.
This single CD-ROM presents 17 short (2–3-minute) Quicktime, full-color movie animations of selected organic reaction mechanisms, most of which are discussed at the sophomore level. It is an ambitious and timely project that seeks to move beyond the static, snapshot formalism of the curved arrow to a seamless portrayal of electron flow in three dimensions. Each movie, accompanied by text and voice, is shown twice and includes at least one view or rotation of an intermediate or transition state. The entire series can be examined in an hour. The animations are interactive as controlled by a QT slide bar. They vary in scope, quality, and clarity. Quite effectively presented are alkene bromination, hydrogenation and hydrohalogenation, carbonyl enolization–alkylation, carbocation rearrangement, and E2 elimination. A few other, more advanced, topics such as the SN2′, kinetic aldol, and Baeyer–Villiger reactions are also included. Carbonyl addition and acyl substitution are exemplified by imine formation and ester saponification. Reactions of aromatics are not presented. In this package, the reaction pathways are primarily based on changes in overall geometry and bonding so the emphasis is on highlighting those bonds being broken and those being formed. Transition states are identified by the appearance of a uniform color over all atoms, orbitals, and bonds. Changes in hybridization and attendant stereochemistry are nicely depicted but these animations are not meant to illustrate or model the molecular orbital basis for reactivity. As an example, the Diels–Alder reaction is shown proceeding with endo specificity via a disrotatory motion of the diene and subsequent rotation of the cycloadduct to a half chair conformation but it is not presented as a HOMO–LUMO interaction. In many of the mechanisms the reacting centers and relevant interacting orbitals appear in vividly contrasting colors, which aides visualization but may lend the unintended impression that some reactants, intermediates, or products are in antibonding states. A useful adjunct is an indexing guide which links the 17 animations to specific page references in 13 major organic chemistry texts. Alan M. Rosan Department of Chemistry Drew University Madison, NJ 07940
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Journal of Chemical Education • Vol. 75 No. 8 August 1998 • JChemEd.chem.wisc.edu
