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en:reactivity:radical_addition:enpart [2026/09/16 17:02] – abcen:reactivity:radical_addition:enpart [2026/09/18 15:08] (current) – abc
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 ====== Energy Partitioning ====== ====== Energy Partitioning ======
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 Although we have obtained a powerful index of reactivity we remain uncertain of the factors that determine that reactivity. So, let us turn to energy partitioning and divide activation energies into their main parts: energies of former reagents,  //E<sup>R</sup>// and //E<sup>M</sup>//, and interaction energies, //E<sup>int</sup>//. Figure 2 shows the results of such partitioning. The whole situation seems to be complicated enough, each of those parts being greater in absolute value than the resulting activation energy, and no clear correlations are visible.  Although we have obtained a powerful index of reactivity we remain uncertain of the factors that determine that reactivity. So, let us turn to energy partitioning and divide activation energies into their main parts: energies of former reagents,  //E<sup>R</sup>// and //E<sup>M</sup>//, and interaction energies, //E<sup>int</sup>//. Figure 2 shows the results of such partitioning. The whole situation seems to be complicated enough, each of those parts being greater in absolute value than the resulting activation energy, and no clear correlations are visible. 
 Moreover, intermolecular interaction energy values are antibate to activation energies, so they cannot be the main and the only factor of reactivity. Moreover, intermolecular interaction energy values are antibate to activation energies, so they cannot be the main and the only factor of reactivity.
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 Thus, the complete description of the radical addition reaction requires the simultaneous consideration of these two terms: intra- and intermolecular reforming. Let us choose //E<sub>0</sub><sup>def</sup>// to represent the first factor. And the second, intermolecular term, can be described by means of the PMO theory, especially since our case is a good one for π-approximation. Thus, the complete description of the radical addition reaction requires the simultaneous consideration of these two terms: intra- and intermolecular reforming. Let us choose //E<sub>0</sub><sup>def</sup>// to represent the first factor. And the second, intermolecular term, can be described by means of the PMO theory, especially since our case is a good one for π-approximation.
  
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 **Figure 2.** Partitioning of activation energies of reactions //HOO<sup>•</sup> + CH<sub>2</sub>CHX//.  **Figure 2.** Partitioning of activation energies of reactions //HOO<sup>•</sup> + CH<sub>2</sub>CHX//. 
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 {{:reactivity:radical_addition:enpart-2.png?direct&50 |}}Details of histogram: \\  {{:reactivity:radical_addition:enpart-2.png?direct&50 |}}Details of histogram: \\ 
 (a), //E<sup>M</sup>//, the change of monomer's total energy including //E<sup>def</sup>//, (b); %%(c)%%, //E<sup>R</sup>//, the change of total energy of //HOO//; (d), //E<sup>int</sup>//, total energy of interaction; the dashed block (e) shows the value of interaction between reactive centers; (f), resulting value of activation barrier //E<sub>a</sub>// (//ΔΔH<sup>≠</sup><sub>f</sub>//). (a), //E<sup>M</sup>//, the change of monomer's total energy including //E<sup>def</sup>//, (b); %%(c)%%, //E<sup>R</sup>//, the change of total energy of //HOO//; (d), //E<sup>int</sup>//, total energy of interaction; the dashed block (e) shows the value of interaction between reactive centers; (f), resulting value of activation barrier //E<sub>a</sub>// (//ΔΔH<sup>≠</sup><sub>f</sub>//).
 +<html><br style="clear:both"></html>
  
 **Figure 3.** **Figure 3.**
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