Positively charged reactants

Direct attack at a ring carbon, even C-3, is normally slow (a) because the concentration of free pyridine in equilibrium with the pyridinium salt is extremely low, and (b) attack upon the salt would also require the positive pyridinium cation to bond to a positively charged reactant. 

This reaction profile of the polymer complex has some similarities with the phenomenon of the polyelectrolyte-catalyzed reactions. It has been reported that the reactions between two positively charged species in aqueous solution are drastically accelerated in the presence of polyanionsS2 84 For example, the electron-transfer reaction between [Co(IIIXen)2(Py)Cl]2+ and [Fe(IIXOH2)6]2+ is very slow because the reaction occurs between two cations however, the addition of a small amount of poly(styrenesulfonate) accelerates the reaction by a factor of 103 84). This result is also interpreted as indicating that the two positively charged reactants are both concentrated in the polyanion domain, so that they encounter each other more frequently [Fig. 17(b)]. 

Constants for Electron Transfer Reactions Positively Charged Reactants °... 

Double bonds contain a high density of high energy electrons associated with the n-bond. This region of high electron density is attractive to positively charged reactants. 

The outer molecular space is partitioned by nodal surfaces into different portions. In the molecular plane on the side of the hydrogens, there is a positive region where the approach of a positively charged reactant is disfavored. On the opposite side W (r) is negative and the approach of a positive charged reactant is favored. The anisotropy of the potential is similar to that produced by a dipole, but the picture given... 

Figure 4.3.1 Examples of reduction processes with different contributions of the migration current (a) positively charged reactant, (b) negatively charged reactant, (c) uncharged reactant.

Charge is conserved, as it must be in all reactions. Here, the reactant is uncharged, and the net charge on the products is 0. In a conceptually related dissociation, a net charge of -bl is conserved when a positively charged reactant dissociates to a carbocation and a neutral molecule. 

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