Bond-breaking mechanisms

In both cases it has been proposed that the pyruvoyl group forms a positively charged Schiff base with the substrate. The bond-breaking mechanisms are not obvious but some ideas have been proposed.281-2833 The ATP may arise from reaction with an intermediate acetyl phosphate.282 SeeEq. 15-61. 

Cottrell, Graham, and Reid have shown that the pyrolyses of nitroethane and nitropropane probably do not proceed by a bond breaking mechanism. 

B. Jana, S. Pal, and B. Bagchi, Hydrogen bond breaking mechanism and water reorientational dynamics in the hydration layer of lysozyme. J. Phys. Chem. B, 112 (2008), 9112. 

The mechanism and the rate of hydrogen-bond breaking in the hydration layer surrounding an aqueous protein have been studied by using a time correlation function technique to understand these aspects in the hydration layer of lysozyme. Water molecules in Ihe layer are found to exhibit three distinct bond-breaking mechanisms compared to bulk reorientation [4]. The reorientation processes are associated wilh the hydrogen-bond breakin switching events (HBSE). Three important characteristics that are common for almost aU of the reorientation processes... 

Related to the above discussion of the hydrogen-bond-breaking mechanism and also the survival time of a layer, the study of HB hfetime dynamics has proven to be a useful tool to understand water dynamics arising from the extended HB network. 

At room temperature, these HBs can break and re-form quite rapidly, leading to the rearrangement of the network. At the microscopic level, we need to understand the lifetime and bond-breaking mechanism of individual HBs between two neighboring water molecules. In the case of a water molecule, such bond-breaking events lead to the spatial/rotational displacements that in turn lead to the translational and rotational diffusion of water molecules. Therefore, the basic mechanism of the microscopic dynamics in water is expected to be different from a simple liquid made of nearly spherical units, Uke in the case of argon. 

Thus, the reaction must have occurred via bond-breaking mechanism (a) because the product formed via mechanism (b) would retain both of its original oxygen atoms. 

This paper is essentially an extension of those treatments in which a somewhat more detailed model of a liquid or an amorphous polymer is considered and a variety of properties are calculated on the basis of that model. In particular, we consider that the liquid or polymer may be described by a crystalline array of molecules interacting p irely by van der Waals forces and then calculate the theoretical tensile strength, surface energy, work of vaporization. Young s modulus, compressibility, and coefficient of thermal expansion on the basis of that model. T hese results are compared to ex perimentally observed values for a variety of liqtiids and polymers. We ignore the effects of "bond breaking" mechanisms just as previous authors and consider only a hi ly idealized model. 

In ternary or more complex partly covalent oxides, some surfaces have a weak polarity, although they are considered to be non-polar according to Tasker s classification. However, the charge compensation on these weakly polar surfaces is more easily achieved than on polar surfaces, since it only involves a bond-breaking mechanism. 

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