More O Ferrall-Jencks plot

Energy surfaces of this type appear to have been described first by Hughes et al. in 1936. Their current popularity and utility are a consequence of developments by Albery, More O Ferrall, and Jencks, and they are sometimes called More O Ferrall plots or More O Ferrall-Jencks plots. We will refer to them as RIP diagrams, this designation arising from the symbolism in Fig. 5-19. 

In Figure 7.21 we show projections of the surfaces in Figure 7.20 of the sort we just described both axes represent an individual reaction coordinate. In other words, these are what one would see if the surfaces of Figure 7.20 were viewed directly from the top with no topographical features included. The diagonal lines represent the Sn2 reaction paths, and the positions of the transition states are marked with a heavy dot. These two-dimensional projections are known as More O Ferrall-Jencks plots (also known as More O Ferrall plots, or More O Ferrall-Albery-Jencks plots). As substitution on the alkyl group increases, the Sn2 reaction paths develop more curvature, and the transition state moves toward the carbo-cation quadrant of the plot. Each solid line (linear and curved) in these diagrams would be... 

How movement along a More O Ferrall-Jencks plot can be the composite of two movements, one perpendicular and one parallel to the reaction coordinate. The arrows show the directions predicted by the discussion in the text, while the colored arrow shows the composite response. 

Using a More O Ferrall-Jencks Plot in Catalysis... 

Let s examine E2 eliminations with More O Ferrall-Jencks plots. We also examine similar scenarios in Chapter 10. 

A More O Ferrall-Jencks plot of hydration of a carbonyl compound. As the acid becomes stronger, the transition state has less nucleophilic attack (A to B), and the a value remains the same. 

As with all reactions that have possible competing pathways, we can examine the interdependence of the various mechanisms with More O Ferrall-Jencks plots. In Figure 10.11, the diagonal shows the E2 reaction, which is a composite of the El and ElcB mechanisms shown proceeding at the bottom-left and top-right corners, respectively. We start our analy-... 

A More O Ferrall-Jencks plot allows one to predict how deprotonation and leaving group departure in an E2 reaction change as a function of each other. We show what happens if the leaving group is made better. 

Table 10.7 lists changes to the transition state structure for E2 reactions that occur when structural changes are made to the reactants and solvent. Confirm each of these by looking at More O Ferrall-Jencks plots. 

Using a More O Ferrall-Jencks plot, analyze how the position of the Sn2 transition state changes for the reaction of n-butylchloride with azide under the following conditions. 

Clearly, the nature of the transition state is varying as we introduce substituents. This should remind you of our discussion of such effects in Chapters 7,10, and 11, and in particular this would appear to be an excellent system for a More O Ferrall-Jencks plot. Indeed, such a plot has been used to analyze this reaction, and one is given in Figure 15.25. 

The Use of Pulse Radiolysis to Measure the pK s of Protonated Ketyl Anions 402 Discovery of the Marcus Inverted Region 406 Using a More O Ferrall-Jencks Plot in Catalysis 410... 

Fig. 8. More O Ferrall-Jencks plot for the general base catalyzed addition of a nucleophilic to an unsaturated center with a preferred concerted pathway...

---