====== Objects of Investigation: Basic Set of Reactions ====== To make a background of discussions of reactivity, the following set of reagents was chosen: radicals //CH₃^•//, //CH₃O^•//, //CCl₃^•//, //CF₃^•//, and //HOO^•// and vinyl monomers //CH₂CHX//: ethene (//Eth//, //CH₂CH₂//), propene (//Prop//, //CH₂CH-CH₃//), styrene (//St//, //CH₂CH-C₆H₅//), vinylacetate (//VA//, //CH₂CH-OCOCH₃//), methylacrylate (//MA//, //CH₂CH-COOCH₃//), acrylic nitryl (//AN//, //CH₂CH-CN//), vinylchloride (//VCl//, //CH₂CHCl//), and vinylidenchloride (//VCl2//, CH₂CCl₂). For these monomers, both positions of attack were considered. In addition, reactivity of monomers with conjugated bonds toward //CH₃^•// and //HOO^•// were considered((butadiene (//Bu2ene//), hexatriene (//Hex3ene//), vinylnaphthalene (//ViNaph//), 2- and 4-vinylpyridines (//ViPy//), and 2- and 4-vinylpyrimidines (//ViPm//) )). The total number of calculated Transition States was somewhere around 100. All TSs had the same topology as shown [[.:ts|above]]. Among the possible conformations of products, those ones were chosen in which the new substituent (formerly the radical) was perpendicular to the original plane of the monomer. Table I presents the main geometric characteristics of TS of β-attack (attack on the unsubstituted position of the //C=C// bond). One may judge from the table that TS geometries within a series remain practically constant. Comparison of r^prod/r^≠ values shows that the //CH₃^•// addition reaction has the earliest TS and the //HOO^•// addition the latest, in due agreement with experimental facts. ** Таблица I. Geometries of TSs of β-addition of radicals to the main set of monomers. ** ^ Parameter ^ //HOO^•// ^ //CH₃^•// ^ //CH₃O^•// ^ //CCl₃^•// ^ //CF₃^•// ^ | //r^≠// (Å) | 1.945 ± 0.01 | 2.24 ± 0.02 | 2.05 ± 0.02 | 2.21 ± 0.01 | 2.22 ± 0.01 | | φ (°) | 101 | 105 | 100 | 107 | 106 | | θ (°) | 15 | 10 | 11 | 13 | 11 | | //R_CC// (Å) | 1.405 ± 0.01 | 1.385 ± 0.01 | 1.395 ± 0.01 | 1.395 ± 0.01 | 1.395 ± 0.01 | | //r^prod/r^≠// | 0.735 ±.005 | 0.685 ±.005 | 0.689 ±.001 | 0.702 ±.005 | 0.721 ±.003 | | //r^≠//, distance between reactive centers in TS; //r^prod// – in product); φ, angle of attack; θ, torsion of //CH// bonds relative to the horizontal plain. |||||| ---- [ [[.:thermo|Next]] ] [ [[.:|Top]] ]