Solvent-free aerobic oxidative cleavage of alkenes catalyzed by N-hydroxyphthalimide

Abstract

The aerobic oxidative cleavage of a-methylstyrene and other benzylic olefins catalyzed by N-hydroxyphthalimide (NHPI) under solvent-free conditions is described. The reaction was remarkably accelerated by the addition of azo-initiator (2,2 0 -azobis(2-methylpropionitryl)) or transition metal salts (Mn, Cu, Co) in combination with NHPI. Alkylammonium salts and acetophenone were successfully applied to increase the solubility of the polar NHPI catalyst in non-polar substrates. The effects of the catalyst and reaction parameters on the conversion of the substrate and the selectivity for ketones were investigated. New insights into the oxidation mechanism and NHPI-ammonium salt interaction are presented.

The Oxidative Polymerization of Vinyl Monomers in the Presence of N‐Hydroxyphthalimide

“…A similar mechanism is proposed by Pyszny et al [59] in the study of the oxidative cleavage of benzylic α-olefins catalyzed by NHPI. On the other hand, Patten et al [60] investigated the bulk polymerization of styrene in the presence of NHPI and found that the anaerobic polymerization was not a "living process".…”

“…A similar mechanism is proposed by Pyszny et al . in the study of the oxidative cleavage of benzylic α ‐olefins catalyzed by NHPI.…”

Solvent‐Free Aerobic Oxidation of Ethylbenzene Promoted by NHPI/Co(II) Catalytic System: The Key Role of Ionic Liquids

“…At this point, our working hypothesis for the interpretation of these data relies on the effect of ILs on the solubility of Co(II) salts, but more importantly, on the NHPI. As said, the effect of alkylammonium salts to NHPI catalytic performances has been already reported . However, it was concluded that better solubility of NHPI under the tested conditions were due to the formation of vesicles, incorporating and solubilizing the catalyst.…”

“…As said, the effect of alkylammonium salts to NHPI catalytic performances has been already reported. [16,17,31] However, it was concluded that better solubility of NHPI under the tested conditions were due to the formation of vesicles, incorporating and solubilizing the catalyst. In order to better understand the role of ILs in the solubilization of NHPI, we embarked on a more detailed NMR study of the NHPI -IL interaction.…”

Oxidation of Long-Chain α-Olefins Using Environmentally-Friendly Oxidants

“…The high catalytic activity of NHPI has been demonstrated in many free-radical oxidation reactions using oxygen, including the aerobic cleavage of alkenes. α-Methylstyrene and its derivatives were oxidized to acetophenones by oxygen in the presence of NHPI combined with cobalt(II) compounds, azo compounds, or alkylammonium salts [ 41 ]. Unfortunately, the cleavage of double bonds of non-aromatic alkenes, such as 1-cyclohexene or 1-dodecene, did not occur.…”