Aerobic oxidation of isopropylaromatic hydrocarbons to hydroperoxides catalyzed by N-hydroxyphthalimide

Abstract

The oxidations of cumene, 4-isopropylbiphenyl, 1-methoxy-4-(1-methylethyl)benzene, 2-isopropylnaphthalene, 2-methoxy-6-(1-methylethyl)naphthalene, 2,6-diisopropylnaphthalene and 4,4 0 -diisopropylbiphenyl to the corresponding hydroperoxides with oxygen, at 60°C, in the presence of N-hydroxyphthalimide (NHPI) and AIBN have been performed. Process inhibition was observed at temperatures above 60°C resulting in lower conversion. A favorable effect of electron-donating substituents (methoxy, phenyl) on the reaction rate were described. NHPI was separated from the cumene oxidation product and recycled 5 times. It has been demonstrated that oxygen can be replaced by air.

Kinetics and Mechanism of Cumene Oxidation Initiated by N‐Hydroxyphthalimide

“…The insignificant temperature effect on the rate of the developed process can also be seen from the behavior of the rate constant (Table ) whose value remains basically unchanged at 110–120°C. Similar “inhibition” in NHPI catalytic processes, including the lowering of the reaction rates with increasing temperature, has been widely reported in the literature regarding the oxidation of alkylaromatic substances .…”

“…It should be noted that the catalyst precipitated practically quantitatively at the end of the reaction, and after cooling the solution to 0°C. Such catalyst regeneration allowed for repeated usage of the catalyst in the production of different hydroperoxides runs . The cumene oxidation was carried out using atmospheric oxygen in a glass reactor with a capacity of 10 cm 3 adopting the flow closed type equipment with stirring intensity in the presence of NHPI as a catalyst.…”

N-Hydroxyphthalimide Supported on Silica Coated with Ionic Liquids Containing CoCl2 (SCILLs) as New Catalytic System for Solvent-Free Ethylbenzene Oxidation

“…The advantage of NHPI is its availability, low price, and a simple method of its synthesis from phthalic anhydride and hydroxylamine [3]. Because of its poor solubility in hydrocarbons, the processes are usually carried out in polar solvents, e.g., in acetic acid [7], acetonitrile [8], or benzonitrile [9]. The use of compressed CO 2 [10][11][12] and ionic liquids [11,[13][14][15][16][17][18] has also been reported.…”

“…In order to use NHPI in industrial processes, it is necessary to develop efficient methods of its recovery and reuse. NHPI separation by evaporation of organic solvent [8,19] or CO 2 has been described in literature [10,11]. However, this simple method may prove to be ineffective, if the product of the reaction will be characterized by high polarity and related good solubility of NHPI.…”

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

“…[7] NHPI-catalyzed oxidation reactions are most often carried out in polar solvents, such as acetic acid, acetonitrile (MeCN), and benzonitrile (PhCN), due to its poor solubility in non-polar hydrocarbons. [7][8][9][10] The complete solubilization of NHPI catalyst is essential, as NHPI can exploit its hydrogen atom donating action in the HAT processes shown in Figure 1 only provided it is under homogeneous conditions. However, the use of polar solvents limits the implementation of the catalytic system in real oxidative processes.…”