Liquid-Phase Oxidation Kinetics of Phenyl-<i>Gem</i>-Dichlorocyclopropane
Roducts based on <i>gem</i>-dichlorocyclopropyl-ketone are promising syntons for the production of biologically active and medicinal compounds. A possible approach to its synthesis can be the liquid-phase oxidation of a styrene derivative, phenyl-<i>gem</i>-dichlorocyclopropane, with decom-position of the intermediate hydroperoxide according to a known scheme. Using kinetic methods on an automated manometric unit with constant regulation of oxygen pressure with computer registration, the kinetics of phenyl-<i>gem</i>-dichlorocyclopropane oxidation initiated by azobisisobutyronitrile has been studied (1). The initiation rate was determined using a known inhibitor of radical chain oxidation of a -tocopherol. Using the modern DFT method M06-2X / MG3S, calculations of the bond dissociation energy are carried out. This method allows determining the bond strength with high accuracy (~1.5 kcal<sup>.</sup>mol<sup>-1</sup>). It was established that under the conditions studied (60°C, the initiator is AIBN, W<sub>i</sub> = 5.3 <sup>.</sup> 10<sup>-8</sup> mol (lЧs)<sup>-1</sup>), the initiated oxidation of compound 1 proceeds via a radical-chain mechanism with a quadratic chain break. This is confirmed by the fact that the oxidation rate ( W <sub>0</sub>) does not depend on pressure in the range of 90-100 kPa and is directly proportional to concentration 1 and the square root of the initiation rate. The obtained value of the oxidizability parameter for 1 is k <sub>2</sub><sup>.</sup> k <sub>6</sub><sup>-0.5</sup> = 5<sup>.</sup>10<sup>-5 </sup>(60 <sup>о</sup>С). The rate constant for the continuation of the chain k <sub>2</sub> is estimated. The bond strengths calculated by the M06-2X / MG3S method are consistent with the values obtained. Thus, the obtained values of k <sub>2</sub><sup>.</sup> k <sub>6</sub><sup>-0.5</sup> and k <sub>2</sub>, as well as the calculated strength values of the tertiary C-H bonds in compound 1 indicate that the corresponding hydroperoxide from 1 cannot be formed in sufficient concentration (in 24 hours at 60 <sup>о</sup>C its yield does not exceed 0.1%).