Reaction profile diagram

What we can display is the free energy of reactants, transition states, intermediates, and products. They are shown separated on a horizontal scale for convenience the abscissa is not defined. This display will be called a reaction profile diagram. 

Two examples of reaction profile diagrams are shown in Fig. 4-5 for the A = I <=s P sequence. The rate constants chosen give values of kss of 0.99 s-1 in case (1) and 0.0099 s l in (2). In the first diagram, step 1 is almost rate-controlling, and in the other, step 2. In Fig. 4-5 note the depth of the well in which the intermediate resides... 

Reaction profile diagrams for two sets of rate constants in the system A-—> I—h... 

Other authors identify the RCS as the one with the highest-lying transition state in a reaction profile diagram. But this, too, fails in the general sense it does not allow for irreversible reactions where an intermediate may be more stable than the reactants. 

Wilkinson s method for, 32-33 with respect to a species, 6 with respect to concentration, 16 with respect to time. 16 Reaction profile diagram. 84—85 Reaction rates, effect on of concentrations, 9 of ionic strength, 206-214 of light, 9... 

Fig. 11 Yields of the water trapping products Pq at the single guanines, and reaction profile diagram for the electron transfer as well as water trapping of the guanine radical cations...

Fig. 14 Reaction profile diagram for the hole transfer from a guanine radical cation (G +) to a distant GGG sequence via the activated hopping mechanism, which also involves adenines (A) as charge carriers...

The other necessary reaction for a BN to VN isomerization is a well precedented 1,5 H shift to convert the linearly conjugated substituted cyclopentadiene (LCC) into the cross conjugated cyclopenta-diene (CCC). The relative lability of BN relative to VN is thus a reflection of the stabilizing conjugation of the substituent in the vinyl isomers and the fact that the formation of LCC from BN is more favorable than the formation of CCC from the retro Diels Alder of VN. The relative energetics for all of these processes is represented in a combined reaction profile diagram shown in Figure 1. 

Figure 1. Combined reaction profile diagram for monomer isomerization.

There must then be some mechanism by which the quickly formed -alkene is converted into the more stable Z-alkene, presumably through another intermediate that is more stable than the transition state for alkene inter conversion. This information is summarized on a reaction profile diagram, transition state... 

The Hammond postulate gives information about the structure of transition states. It says that two states that interconvert directly (are directly linked in a reaction profile diagram) and that are close in energy are also similar in structure. So a transition state will be most like the starting material, the intermediate, or the product if it is close in energy to one of these observable structures. 

A is correct. If a catalyst only affected the rate in one direction, the equilibrium would be affected. A catalyst doesn t change the equilibrium. This can also be seen from a reaction profile diagram as shown in question 37. 

In order to understand the Woodward-Hoffmann rules for determining the stereochemistry of several different types of concerted reactions, let us first consider the ground and excited states of a normal reaction. The ground state energy rises continuously to the transition state and then falls to the product. Often, this is the only state shown in such reaction profile diagrams. The excited state is not generally involved in the reaction, but often has a minimum above the transition state, as shown in Fig. 4.4. 

Classroom context. The lessons that we studied occurred over two days. On the first day, a double lesson (80 minutes) was given, starting with a recapitulation of the particulate nature of chemical reactions and factors that influence reaction rate, followed by activation energy, reaction profile diagrams, and the conditions for chemical equilibrium. The next day, a single lesson (40 minutes) elaborated the concept of dynamic equilibrium. No teaeher demonstrations or student practical work were included in the lessons. The topies were presented and discussed in an interactive way with Neil and his students asking many questions. 

Fig. 5. Schematic reaction profile diagram for the decarboxylation solid line) of acetic acid [Eq. (4)] and for the oxidation dashed line) of acetic acid [Eq. (3)]. The activation energy for the reverse oxidation reaction is E (k 3) and for the forward decarboxylation reaction it is Eg (IC4)...

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