Bond breakage, reversible

Based on the principle of microscopic reversibility one may conclude that the intermediate(s) in the off step will be the same as those generated during the k(m pathway, thus iron nitrosyl bond breakage (k 2)... 

These results suggest, thus, that environment-DNA interactions could counterbalance or even reverse the experimentally observed stability of isolated nucleic base anions. As a consequence, the delocalization of an electron over the Watson-Crickbase pair could initiate CX-0 bond breakage from either a pyrimidine or a purine anion. 

The C-0 bond breakage would simply reverse the process. 

The reversibility of the reaction is another important feature of coupling by silanes, titanates, and zirconates. The bond formed in the second stage (see chemical reaction above) is not a permanent bond but is an equilibrium reaction which depends on the amount of water in the system. This is the most important concept in the coupling mechanism. Bonds can form, break, and reform. Water immersion affects the interface, causing bond breakage. Bonds can be reformed again if the internal stress in the polymer matrix does not cause permanent delamination which separates the surfaces. 

Alcoholysis and hydrolysis of siloxane bonds (reverse of Eqs. 9 and 10) provide a means for bond breakage and reformation allowing continual restructuring of the growing polymers. The rate of hydrolysis of siloxane bonds (dissolution of silica) exhibits a strong pH-dependence as shown in Fig. 21. Between about pH 3 and 8, the dissolution rate increases by over three orders of magnitude in aqueous solution. Partial replacement of water (pH 9.5) with methanol decreases the solubility by over a factor of 20 as shown in Table 10. 

In these systems capsules are broken upon damage and reactive monomers that are able to close the scratch fill the break. Another possibility is the function of the polymers that show reversible bond breakage and formation. Examples are groups that can undergo Diels-Alder reactions such as maleimide and furan rests. Sol-gel-derived sihca particles that contain these groups can be used for the preparation of self-healing nanocomposites [56]. 

We will assume that the activation energy of the reverse of a reaction step does not depend on of the rank of this step, but it is in fact the bond breakage between a promoter and agglomerate, which is more likely with increasing /. If a is the length of the order of magnitude of the network of initial solid A, the surface rate coefficient of the reverse reaction can be written ... 

Dynamic light-scattering experiments or the analysis of some physicochemical properties have shown that finite amounts of formamide, A-methylformamide, AA-dimethyl-formamide, ethylene glycol, glycerol, acetonitrile, methanol, and 1,2 propanediol can be entrapped within the micellar core of AOT-reversed micelles [33-36], The encapsulation of formamide and A-methylformamide nanoclusters in AOT-reversed micelles involves a significant breakage of the H-bond network characterizing their structure in the pure state. Moreover, from solvation dynamics measurements it was deduced that the intramicellar formamide is nearly completely immobilized [34,35],... 

Industrial examples of adsorbent separations shown above are examples of bulk separation into two products. The basic principles behind trace impurity removal or purification by liquid phase adsorption are similar to the principles of bulk liquid phase adsorption in that both systems involve the interaction between the adsorbate (removed species) and the adsorbent. However, the interaction for bulk liquid separation involves more physical adsorption, while the trace impurity removal often involves chemical adsorption. The formation and breakages of the bonds between the adsorbate and adsorbent in bulk liquid adsorption is weak and reversible. This is indicated by the heat of adsorption which is <2-3 times the latent heat of evaporahon. This allows desorption or recovery of the adsorbate from the adsorbent after the adsorption step. The adsorbent selectivity between the two adsorbates to be separated can be as low as 1.2 for bulk Uquid adsorptive separation. In contrast, with trace impurity removal, the formation and breakages of the bonds between the adsorbate and the adsorbent is strong and occasionally irreversible because the heat of adsorption is >2-3 times the latent heat of evaporation. The adsorbent selectivity between the impurities to be removed and the bulk components in the feed is usually several times higher than the adsorbent selectivity for bulk Uquid adsorptive separation. 

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