Reacting bond rules

Note that any factor that stabilizes a reaction intermediate will also stabilize the transition state leading to that intermediate. See also Leffler s Assumption Reacting Bond Rules... 

ACIDITY FUNCTION BUNNETT-OLSEN EQUATIONS DECREE OF DISSOCIATION HAMMETT EQUATION HAMMOND PRINCIPLE/POSTULATE LEFFLER S ASSUMPTION REACTING BOND RULES HANES PLOT... 

Reactant conversion into its mirror image, NARCISSISTIC REACTION REACTING BOND RULES REACTING ENZYME CENTRIFUGATION REACTION COORDINATE DIAGRAM POTENTIAL ENERGY DIAGRAM SADDLE POINT... 

These arguments are summarized as the reacting bond rules 47... 

Use the reacting bond rule to predict the effect on position of transition state of electron supply at nucleophile and at leaving group in the example considered in the text, gp. 246-250. 

Using the reacting bond rules, analyze the change in location of the S 2 transition state expected when the nucleophile is replaced by a better one. Compare the prediction with Hoffmann s analysis of the k0TJkBr ratio (Section 4.3, p. 192). 

The predictions of the reacting bond rules are borne out by the p values of Table 7.11. More negative charge is localized on when the leaving group is the less reactive +N(CH3)3 than when it is the more reactive I-. The isotope effects mentioned above fit this explanation if it is assumed that when Br is the leaving group the proton is approximately half transferred at the transition state. The smaller value of kulkD when +N(CH3)3 departs is a result of an unsym-metrical transition state in which the proton is more than half transferred. 

Figure 8.3) will move the transition state to an earlier point. Since strengthening acid HA facilitates motion Rx (transfer of proton from HA to carbonyl oxygen coupled with attack of nucleophile), the transition state will tend to come earlier with respect to this motion that is, it will be shifted in the direction indicated by the arrow R2 in Figure 8.3. But proton motion is also involved in the vibration designated by i and J 2 in Figure 8.3 reacting bond Rule 2 states that change in structure will shift the transition state in the direction indicated by the change. Here, strengthening acid HA aids motion i-...

One method of deciding between Mechanisms I and II is to look at the trend of a in acid-catalyzed additions of various nucleophiles to a carbonyl group.26 It follows from the reacting bond rules that in true general acid catalysis (Mechanism I), the sensitivity of the rate to acidity of the catalyst, and therefore also a, should decrease as the species adding is made more nucleophilic. The reason is that this variation will cause the change in reaction coordinate shown in... 

Two arguments in favor of the transition state in equation (30) have been presented. First, the calculated second-order rate constant for attack of free semicarbazide on protonated / -nitrobenzaldehyde according to equation (32) exceeds the maximum rate for a diffusion-controlled reaction . Second, application of the solvation and reacting bond rules appears to favor equation (30) over equation (32)... 

---