Studies on the Autoxidation of Phenyl Cycloalkanes

Abstract

The products of the autoxidation of phenyl cyclopropane (I), phenyl cyclobutane (II), phenyl cyclopentane (III), phenyl cyclohexane (IV), phenyl cycloheptane (V) and phenyl cyclooctane (VI) were analyzed after reduction of the reaction mixtures with LiAlH4. As products of the attack on the α‐CH bonds the corresponding 1‐phenyl cycloalkanols and 1‐phenyl alkan‐1‐ols were found. In the case of phenyl cyclopropane some SR2 ring opening probably takes place. The oxidabilities \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm k}_{\rm p} /\sqrt {{\rm k}_{\rm t}} $\end{document}, the chain termination constants kt, the absolute chain propagation constants kp and the relative chain propagation constant (kp)rel were determined for the phenyl cycloalkanes I—VI. As it is to be expected on the basis of the I‐strain concept the autoxidation rate of phenyl cyclopentane (III) is considerably higher than that of phenyl cyclobutane (II) and phenyl cyclohexane (IV).

Kinetics and regioselectivity of the Autoxidation of Alkylaromatic Hydrocarbons

“…If an H atom is abstracted from the tertiary C-H bond of phenyl cycloalkanes, a change of hybridization from sp3 to sp2 takes place at the tertiary carbon atom. The differences in the reaction rates of various phenyl cycloalkanes with cumylperoxy radicals (Table 2) [28] fully correspond to expectations. A great number of examples for such I-strain effects in reactions where cycloalkyl radicals are formed is published in literature [37].…”

“…1.9 a) calculated from the oxygen absorption rates in the presence of 0.5 -2.0moll-I cumene hydroperoxide ogous results are obtained in the autoxidation of the phenyl cycloalkanes without addition of cumene hydroperoxide (Table 1) [28]. This corresponds to the Istrain conception formulated at the end of the 50s by H.C. Brown [35,36].…”

“…This research group of the Ukrainian Academy of Sciences has carried out a great number of kinetic studies on the basis of the copolymerization equation. Table 6 also shows the data of our own studies on the oxidation of the given hydrocarbons in the presence of cumene hydroperoxide [34]; the rate constants are suf- [34] b) determined by competitive oxidations applying the copolymerization equation [45] c, determined by competitive oxidations (2nd method, Formula Scheme 5 ) [28,39,511 ficiently consistent. The constants shown under a) and b) in Table 6 are absolute rate constants.…”

“…The other characteristic constant can then be calculated from the oxidizability k,/\/2k,. No method exists for the independent determination of k,, but several methods have been deceloped for the determination of k, [20-271. Here only the method of chemiluminescene [24 -261 will be considered because we used it in collaboration with the Institute of Chemical Physics of the Academy of Sciences of the Soviet Union [28,291. The basis of the method is the fact that the chain termination between two peroxy radicals is connected with a chemiluminescence whose intensity is considered to be proportional to the termination rate (Formula Scheme 3).…”

Reaktivität und Selektivität bei der Oxidation von Styrolderivaten. V. Untersuchungen zur Oxidation vonα-substituierten Styrolen

“…Das steht im Einklang mit den Ergebnissen der Oxidation von Phenylcycloalkanen, in der sich Phenylcyclopropan als sehr schwer oxidierbar erwies [13]. Styrol 1e liefert bei der Oxidation in PhCl-Lösung bei 90 -100 °C vorwiegend (85 -90 Mol%) die Produkte der oxidativen C=C-Spaltung (Benzaldehyd und Formaldehyd) und 10 -13 Mol% 1-Phenyl-oxiran; dies stimmt mit den Angaben in [8] überein.…”