Addition Of Cyclohexyl Radicals Research Articles

ChemInform Abstract: Alkane Carbonylation Photocatalyzed by Aromatic Ketones Under High CO Pressure.

Abstract Aromatic ketones photocatalyze the carbonylation of alkanes to the corresponding aldehydes at room temperature under high CO pressures (20 – 80 atm). In the presence of CCl 4 , cyclohexanecarbonylchloride is formed from cyclohexane; this reaction was used to determine the rate of addition of cyclohexyl radical to CO.

Transformations of ortho-quinones in the γ-radiolysis of their solutions in cyclohexane

The transformations of 4-tert-butyl-1,2-benzoquinone (I), 3,5-di-tert-butyl-1,2-benzoquinone (II), and 4-methoxy-5-tert-butyl-1,2-benzoquinone (III) in deaerated cyclohexane solutions under exposure to γ-radiation were studied. It was found by chromatography-mass spectrometry and 1H and 13C NMR spectroscopy that the addition of cyclohexyl radicals at the C=O bond in compounds I–III resulted in monoalkyl ethers, whereas cyclic ketal XXI was also formed in the case of compound II. Moreover, quinone I afforded mixed O-and C-alkylation products, and the adduct of cyclohexyl radicals and quinone II at the C=C bond was the source of dimeric products.

Thermisch initiierte Addition von Alkanen an Alkene. V. Addition von Cyclohexan an Oct‐1‐en in einer freien Radikalkettenreaktion unter überkritischen Bedingungen

Thermal Addition of Alkanes to Alkenes. V. Addition of Cyclohexane to 1‐Octene in a Free Radical Chain Reaction at Supercritical Fluid ConditionsAlkanes can be added to alkenes in a thermally initiated free radical chain reaction (“ane reaction”). Kinetic and mechanistic studies on the addition of cyclohexane (1) to 1‐octene (2) (molar ratio = 100:1) at 330−450°C and pressures of up to 300 bar have been performed in a high pressure ‐ high temperature flow apparatus (“HP‐HT” apparatus). The free radical chain is initiated by comproportionation of1and2to give alkyl radicals6and7. Addition of cyclohexyl radical6to alkene2and competing abstraction of an allylic hydrogen atom from2give radicals7aand8, respectively. Subsequent stabilization of the radicals7aand8by hydrogen abstraction from1yields the addition product cyclohexyloctane (3) and isomerized octenes (4), respectively. The relative rate of addition and isomerization can be controlled by pressure and temperature. The regioselectivity of the addition reaction was also measured.

Correlation between copolymerization reactivity ratios and rates of radical additions to alkenes

Rates of addition of cyclohexyl radicals to alkenes are measured using the “mercury method”. These rates can be correlated with data of styrene copolymerization. Copolymerization reactivity ratios therefore describe relative reactivities of polymer radicals in addition reactions to alkenes. It turns out that the polymeric benzylic radicals are less selective than the cyclohexyl radicals.

Mechanism of the reaction of cumyloxyl radicals in a mixture of hydrocarbons

Decay reactions of cumyloxyl radicals have been studied in a mixture of cyclohexane and aromatic hydrocarbon. The hydrogen transfer from solvent to oxyl radical increases considerably when small amounts of the aromatic hydrocarbon are present. The addition of cyclohexyl radical to the aromatic ring plays a decisive role in the mechanism of this reaction.

ChemInform Abstract: THE KINETICS OF FREE RADICAL CHAIN REACTIONS IN SOLUTIONS OF TRICHLOROFLUORETHYLENE IN CYCLOHEXANE

The kinetics of the gamma-radiation-induced free radical chain reaction in solutions of C2Cl3F in cyclohexane (RH) was investigated over a temperature range of 87.5–200°C. The following rate constants and rate constant ratios were determined for the reactions: In competitive experiments in ternary solutions of C2Cl4 and C2Cl3F in cyclohexane the rate constant ratio k2c/k2a was determined By comparing with previous data for the addition of cyclohexyl radicals to other chloroethylenes it is shown that in certain cases the trends in activation energies for cyclohexyl radical addition can be correlated with the CCl bond dissociation energies in the adduct radicals.