Dimerization kinetics

Divita G, Rittinger K, Geourjon C, Deleage G, Goody RS. Dimerization kinetics of HIV-1 and HIV-2 reverse transcriptase A two step process. J Mol Biol 1994 145 508-521. 

The ruthenium carbonyl complexes [Ru(CO)2(OCOCH3)] n, Ru3(CO)12, and a new one, tentatively formulated [HRu-(CO)s ] n, homogeneously catalyze the carbonylation of cyclic secondary amines under mild conditions (1 atm, 75°C) to give exclusively the N-formyl products. The acetate polymer dissolves in amines to give [Ru(CO)2(OCOCH3)(amine)]2 dimers. Kinetic studies on piperidine carbonylation catalyzed by the acetate polymer (in neat amine) and the iiydride polymer (in toluene-amine solutions) indicate that a monomeric tricarbonyl species is involved in the mechanism in each case. 

Initiation can be most effectively studied in systems with the smallest number of elementary steps in the polymerization reaction. This requirement is fulfilled in living systems (without termination and transfer) with monomers which do not generate polymer chains. By eliminating propagation (or suppressing it to dimerization) kinetically relatively simple systems can be obtained which are suitable for the application of convenient analytical methods. 

C) Diels-Alder Dimerization Kinetics of Some Model Compounds... 

Hitherto, the feedback and TG/SC modes have found exclusive application in the quantitative study of dimerization kinetics under steady-state conditions (4,5,8). Table 2 provides an extensive list of normalized steady-state tip and substrate currents, as a function of K2 and d/a, which can be used for the analysis of experimental data. The characteristics in Table 2 display the general trends already identified for follow-up chemical reactions (Sec. II.A). (1) For a given d/a value, the tip current varies from a limit corresponding to pure positive feedback (as K2 — 0) to one for negative feedback (as K, —> oo), while the collection efficiency varies from unity to zero as K, increases towards infinity. (2) The feedback and collection currents become most sensitive to kinetics, the closer the tip/substrate separation. Additionally, increasingly fast kinetics become accessible as the tip/ substrate separation is minimized. 

Fig.9.2-3 By combining ten (left) orone thousand (right) iteration steps in each row through the function Smallstep, we can reduce the computational error in the simulation of dimerization kinetics tenfold or thousand-fold respectively, all without increasing the column length of 101 rows.

So, we find the following expression for the dimer kinetic energy ... 

Monomer-dimer kinetics are also reported for the cation tetra-(4-iV-mcthyl-pyridyl)porphineiron(iii) and the anion tetra-(p-sulphophenyl)porphineiron(iii) using concentration-jump and concentration/pH-jump techniques. Rate data for the formation and dissociation of the )w-hydroxo-dimers were obtained. A similar study of the /<-oxo-dimer of [Fe (edta)] was discussed previously. ... 

Both SECM and CV were used to study the dimerization kinetics of nitro radical anions electrogenerated by the one-electron reduction of nitro compounds of biological relevance. Specifically, the reduction of an antituberculosis agent and a bactericidal agent in dimethylsulfoxide was considered. The rate constants obtained by the two techniques were similar. 

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