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In chemistry, a reaction coordinate [1] is an abstract one-dimensional coordinate chosen to represent progress along a reaction pathway. Where possible it is usually a geometric parameter that changes during the conversion of one or more molecular entities, such as bond length or bond angle. For example, in the homolytic dissociation of ...
A catalytic triad is a set of three coordinated amino acid residues that can be found in the active site of some enzymes. [1] [2] Catalytic triads are most commonly found in hydrolase and transferase enzymes (e.g. proteases, amidases, esterases, acylases, lipases and β-lactamases).
Chiral ligands work by asymmetric induction somewhere along the reaction coordinate. The image to the right illustrates how a chiral ligand may induce an enantioselective reaction. The ligand (in green) has C 2 symmetry with its nitrogen, oxygen or phosphorus atoms hugging a central metal atom (in red). In this particular ligand the right side ...
Figure 6:Reaction Coordinate Diagrams showing reactions with 0, 1 and 2 intermediates: The double-headed arrow shows the first, second and third step in each reaction coordinate diagram. In all three of these reactions the first step is the slow step because the activation energy from the reactants to the transition state is the highest.
Reaction Coordinate. (A) Uncatalyzed (B) Catalyzed (C) Catalyzed with discrete intermediates (transition states) Most metal surface reactions occur by chain propagation in which catalytic intermediates are cyclically produced and consumed. [8] Two main mechanisms for surface reactions can be described for A + B → C. [2]
Some multistep reactions can also have apparent negative activation energies. For example, the overall rate constant k for a two-step reaction A ⇌ B, B → C is given by k = k 2 K 1, where k 2 is the rate constant of the rate-limiting slow second step and K 1 is the equilibrium constant of the rapid
In this type of plot (Figure 1), each axis represents a unique reaction coordinate, the corners represent local minima along the potential surface such as reactants, products or intermediates and the energy axis projects vertically out of the page. Changing a single reaction parameter can change the height of one or more of the corners of the plot.
In such cases, the momentum of the reaction trajectory from the reactants to the intermediate can carry forward to affect product selectivity. An example of such a reaction is the ring closure of cyclopentane biradicals generated from the gas-phase thermal decomposition of 2,3-diazabicyclo[2.2.1]hept-2-ene. [21] [22]