Presence Of N-hydroxyphthalimide Research Articles

Kinetic Laws of Oxidation of para-tert-Butylcumene in the Presence of N-Hydroxyphthalimide

Kinetic Laws of Oxidation of para-tert-Butylcumene in the Presence of N-Hydroxyphthalimide

Aerobic oxidation of alkyl aromatics to ketones catalyzed by biomimetic copper complex and N-hydroxyphthalimide (NHPI) under mild conditions

A galactose oxidase-like copper complex (CuIIL) (Ligand: N, N′-bis(2-hydroxy-3,5-di-tert-butylphenyl)-2,2′-diaminobiphenyl) was synthesized and used to catalyze the aerobic oxidation of alkyl aromatics to ketones in presence of N-hydroxyphthalimide (NHPI). The catalytic system exhibited excellent performance and tolerance under mild conditions. Mechanistic studies indicated that NHPI could be activated smoothly to generate phthalimide N-oxyl (PINO) radical in the presence of CuIIL. The kinetic isotope effect (KIE) studies showed that the generation of PINO radical was the rate-determining step.

Efficient Synthesis of 2-Ethylhexanoic Acid via N-Hydroxyphthalimide Catalyzed Oxidation of 2-Ethylhexanal with Oxygen.

An efficient method for the synthesis of 2-ethylhexanoic acid has been reported. The method involves the 2-ethylhexanal oxidation using oxygen or air in the presence of N-hydroxyphthalimide in isobutanol as a solvent under mild conditions. A high selectivity of >99% for 2-ethylhexanoic acid was achieved. The influence of catalyst amount, solvent type and quantity, temperature, and reaction time on the product composition was studied. The developed method is in line with the global trends aimed at developing green oxidation processes as well as having potential for implementation in industry due to its high selectivity, cost-effective oxidizing agent, and mild reaction conditions. The use of isobutanol as a solvent is of crucial importance providing an opportunity for potential producers of 2-EHAL from butanal to employ the less valuable alcohol.

Green and continuous aerobic oxidation of ethylbenzene over homogeneous and heterogeneous NHPI in a micro-packed bed reactor

Aerobic oxidation of ethylbenzene (EB) has emerged as a promising strategy for the selective synthesis of acetophenone (AP) in line with green chemistry. The integration of flow chemistry into the pharmaceutical industry has been facilitated by recent advancements in microreactor technology. In this work, a continuous micro-packed bed reactor platform is developed to determine the kinetics of aerobic EB oxidation in the presence of N-hydroxyphthalimide (NHPI). The microreactor system offers enhanced gas–liquid mass transfer, leading to a 2-order-of-magnitude increase in the space–time yield of EB oxidation compared to traditional batch reactors. Furthermore, the organic catalyst NHPI is covalently anchored on commercial activated carbon through an imidization reaction. The synthetic heterogeneous catalysts exhibit excellent performance in terms of AP yield of 87.4 % and TOF value of 2.21 h−1 for continuous aerobic EB oxidation.

Boosting the visible-light-induced toluene oxidation via synergistic effect between nanoparticulate Pd/BiVO4 photocatalyst and a cyclic nitroxyl redox mediator

Selective organic conversion using semiconductor photocatalysts has been focused on the viewpoint of sustainable synthesis processes. Especially, C-H activation is one of the most attractive reactions. We recently reported photo-oxidation of toluene to benzaldehyde over visible-light responsible Pd-loaded BiVO4 (Pd/BiVO4) photocatalyst. However, it remains challenging due to its low efficiency. Herein, we introduce a novel strategy to apply a cyclic nitroxide compound as an efficient redox mediator along with Pd/BiVO4 for toluene oxidation. Including N-hydroxyphthalimide (NHPI) could significantly expedite the activity of benzaldehyde production up to ca. 28 times compared to without NHPI under blue-to-green light irradiation. The sustainable conditions realized a conversion in high efficiency (apparent quantum yield = 10.8 and 5.4 %@420 and 520 nm, respectively) and with excellent selectivity (>99 %). The excellent efficiency was realized by the synergistic effect between the presence of NHPI and the use of nanoparticulate Pd/BiVO4 with a relatively large surface area.

UV‐induced oxygenation of toluene enhanced by Co (acac)2/9‐mesityl‐10‐methylacridinium ion/N‐hydroxyphthalimide tandem

AbstractThe effect of near‐UV irradiation on the oxygenation of toluene dissolved in MeCN was studied in a stainless‐steel reactor upon O2 bubbling at 80°C and 100°C and 10 atm using Co (acac)2 and 9‐mesityl‐2,7,10‐trimethylacridinium perchlorate (Me2Acr+–Mes ClO4−) as the catalyst and photocatalyst, respectively. In the absence of the process mediator N‐hydroxyphthalimide (NHPI), the rate of PhCH3 oxidation was extremely low, leading to trace amounts of the products formed. The presence of NHPI and the irradiation with UV light enhanced the substrate oxygenation and benzyl alcohol, benzaldehyde, and benzoic acid yield substantially by three to four times. The relative content of the last product was lowest at the beginning of the process as well as in light‐excited oxygenation. In this report, we highlight the mechanism of catalyst, photocatalyst, and mediator combined effect on product yield and composition.

Change of Selectivity in C-H Functionalization Promoted by Nonheme Iron(IV)-oxo Complexes by the Effect of the N-hydroxyphthalimide HAT Mediator.

A kinetic analysis of the hydrogen atom transfer (HAT) reactions from a series of organic compounds to the iron(IV)-oxo complex [(N4Py)FeIV(O)]2+ and to the phthalimide N-oxyl radical (PINO) has been carried out. The results indicate that a higher activating effect of α-heteroatoms toward the HAT from C–H bonds is observed with the more electrophilic PINO radical. When the N-hydroxy precursor of PINO, N-hydroxyphthalimide (NHPI), is used as a HAT mediator in the oxidation promoted by [(N4Py)FeIV(O)]2+, significant differences in terms of selectivity have been found. Product studies of the competitive oxidations of primary and secondary aliphatic alcohols (1-decanol, cyclopentanol, and cyclohexanol) with alkylaromatics (ethylbenzene and diphenylmethane) demonstrated that it is possible to modify the selectivity of the oxidations promoted by [(N4Py)FeIV(O)]2+ in the presence of NHPI. In fact, alkylaromatic substrates are more reactive in the absence of the mediator while alcohols are preferably oxidized in the presence of NHPI.

Transition Metal Salts of Carboxylated Multiwalled Carbon Nanotubes in Combination with N-hydroxyphthalimide as Catalytic Systems for Hydrocarbon Oxidation.

In this study, the transition metal (Co (II), Cu (II), and Mn (II)) salts of carboxylated carbon nanotubes were synthesized and characterized (the determined metal contents were in the range of 0.89–1.16%). The catalytic activity and the possibility for recovery and reuse of the obtained heterogeneous salts were then studied in the solvent-free oxidation of ethylbenzene with oxygen. The oxidation processes were carried out at 80 °C under atmospheric pressure in the presence of N-hydroxyphthalimide. The highest conversion of ethylbenzene, 27%, was obtained with a system consisting of the Cu (II) salt of the carboxylated carbon nanotubes, N-hydroxyphthalimide, and the azo initiator AIBN.

Surface tailoring of polypropylene separators for lithium-ion batteries via N-hydroxyphthalimide catalysis

Surface modification of polyolefine separators for high performance lithium-ion batteries has been a worthwhile research topic. In this work, poly (poly (ethylene glycol) methacrylate) (PPEGMA) was firstly grafted onto polypropylene (PP) separator based on N-hydroxyphthalimide (NHPI) catalysis and activators regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP). Bis(2,2,2-trichloroethyl) azodicarboxylate (BTCEAD) was anchored on the surface of PP separators in the presence of NHPI. Then BTCEAD functionalized PP separator initiated the polymerization of PEGMA by ARGET-ATRP. Thus, structure controllable PPEGMA was grafted on the surface of PP separators. The results of contact angle and electrolyte uptake tests demonstrated that electrolyte wettability of PPEGMA functionalized PP separator has been significantly improved. Electrochemical measurements indicated that the ionic conductivity and discharge capacity retention of cells assembled with PPEGMA functionalized PP separators were distinctly higher than that of cells with pristine PP separator. Herein, we presented a new methodology with high efficiency to modify PP separators under mild condition, which was also applied to other polyolefine separator for high performance lithium-ion batteries. The proposed approach might have many other potential applications in membrane modification field.

Electrochemical alcohols oxidation mediated by N-hydroxyphthalimide on nickel foam surface

Alcohol to aldehyde conversion is a critical reaction in the industry. Herein, a new electrochemical method is introduced that converts 1 mmol of alcohols to aldehydes and ketones in the presence of N-hydroxyphthalimide (NHPI, 20 mol%) as a mediator; this conversion is achieved after 8.5 h at room temperature using a piece of Ni foam (1.0 cm2) and without adding an extra-base or a need for high temperature. Using this method, 10 mmol (1.08 g) of benzyl alcohol was also successfully oxidized to benzaldehyde (91%) without any by-products. This method was also used to oxidize other alcohols with high yield and selectivity. In the absence of a mediator, the surface of the nickel foam provided oxidation products at the lower yield. After the reaction was complete, nickel foam (anode) was characterized by a combination of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), and spectroelectrochemistry, which pointed to the formation of nickel oxide on the surface of the electrode. On the other hand, using other electrodes such as Pt, Cu, Fe, and graphite resulted in a low yield for the alcohol to aldehyde conversion.

Selective Aerobic Oxidation of Secondary C (sp3)-H Bonds with NHPI/CAN Catalytic System

The direct aerobic oxidation of secondarty C(sp3)-H bonds was achieved in the presence of N-hydroxyphthalimide (NHPI) and cerium ammonium nitrate (CAN) under mild conditions. Various benzylic methylenes could be oxidized to carbonyl compounds in satisfied selectivity while saturated cyclic alkanes could be further oxidized to the corresponding lactones with the catalytic system. Remarkably, 25% of isochroman was converted to corresponding ketone with a selectivity of 96%. The reaction was initiated by hydrogen atom abstraction from NHPI by cerium and nitrates under oxygen atmosphere to form PINO radicals. 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) addition experiments showed that the oxidation proceeded via a complex radical chain mechanism and an ion pathway.

Efficient aerobic oxidation of ethylbenzene accelerated by cu species in hydrotalcite

The simply prepared CuMgAl hydrotalcite (CuMgAl-LDH) has been developed as an efficient catalyst for the aerobic oxidation of ethylbenzene to acetophenone in the presence of N-Hydroxyphthalimide (NHPI). Various alkyl arenes could be tolerated under the selected reaction conditions. The kinetic study showed that the oxidation of ethylbenzene is a first-order reaction over CuMgAl-LDH. The mechanism study indicated that CuMgAl-LDH could accelerate not only the conversion of ethylbenzene, but also the transformation of the alcohol intermediate to ketone. The positive effect of surface basicity of the catalyst on the reaction has been observed in the aerobic oxidation of the ethylbenzene.

The use of modified vegetable oil from Crambe abyssinica as a lubricant base for the food industry

Abstract Lubricants that are based on vegetable oils and other renewable resources are the subject of many research studies and can be used in various applications, especially in the food industry, which is characterized by the high quality requirements related to the necessity to develop biodegradable lubricants that are environmentally friendly and do not contain harmful components and are safe to use for people. The objective of the described research was to obtain a base oil with a certain viscosity, which is higher than the viscosity of the initial vegetable oil, and certain lubricating properties. The initial oil derived from Crambe abyssinica was subjected to oxidation in the presence of N-hydroxyphthalimide with or without supercritical CO2 as a solvent. As a final result of this study, base oils meeting the viscosity requirements and having high biodegradability were obtained. The Raman spectra of the modified vegetable oils were evaluated and they were used for the initial assessment of the composition and the evaluation of the presence of harmful chemical compounds.

Aerobic Liquid-Phase Oxidation of Para-tert-Butylcumene to Hydroperoxide

The reaction of aerobic liquid-phase oxidation of para-tert-butylcumene (PTBC) in the presence of N-hydroxyphthalimide has been studied. It has been found that the selectivity for the tertiary hydroperoxide of PTBC is over 95–98% up to a hydrocarbon conversion of 35–50%. The reasonability of the use of this reaction in the process of joint production of PTBC and acetone is shown. The mechanism of the process is discussed.

Kinetics of oxidation of benzyl alcohols with molecular oxygen catalyzed by N‐hydroxyphthalimide: Role of hydroperoxyl radicals

AbstractA kinetic study of the initiated oxidation of benzyl alcohol and cumene by molecular oxygen was performed. The oxidation rate was more enhanced with N‐hydroxyphthalimide (NHPI) in the case of cumene than that of benzyl alcohol. HOOH inhibits cumene oxidation and does not affect the rate of oxidation of benzyl alcohol. It was shown that termination chain reactions of phthalimid‐N‐oxyl radicals (PINO•) does not occur with RОО• and proceeds with HOO•. A kinetic scheme of the process and an equation describing the kinetics of oxidation of benzyl alcohol in the presence of NHPI are proposed. Using the PM7 method, the thermodynamic characteristics of elementary steps of oxidation explaining the obtained results were calculated.

Correlation between the Thermodynamic and Kinetic Parameters of the Oxidation Reactions of Substituted Mononuclear Arenes in the Presence of N-Hydroxyphthalimide

The effect the structure of substituted mononuclear arenes has on the thermodynamic functions of reactions during their oxidation in the presence of N-hydroxyphthalimide is studied. The relationship between the free energy of the oxidation of cumene, isopropyl-m-xylene, isopropyl-o-xylene, isopropyl-p-xylene, m-cymene, p-cymene, and cyclohexylbenzene and its rate at 363–413 K is studied. There is a strong correlation between the free energy of hydrogen abstraction from a tertiary carbon atom with an N-hydroxyphthalimide radical, the rate constant of this reaction, and rate of oxidation for different isomers of the same hydrocarbon, making it possible to predict their relative oxidability.

Selective aerobic oxidation of toluene to benzaldehyde on immobilized CoOx on SiO2 catalyst in the presence of N-hydroxyphthalimide and hexafluoropropan-2-ol

A cost-effective method for the selective oxidation of toluene to benzaldehyde was developed based on immobilized CoOx on SiO2 catalyst with predominating cobaltous ions in the presence of N-hydroxyphthalimide (NHPI) and hexafluoropropan-2-ol (HFIP) using ambient molecular oxygen at room temperature. A toluene conversion of 91% and a selectivity to benzaldehyde of 68% were realized. HFIP was confirmed to work as a restraining agent against the further oxidation of benzaldehyde to benzoic acid on the immobilized CoOx/SiO2 catalyst in the presence of NHPI and HFIP.

Spectroscopic Methods in the Evaluation of Modified Vegetable Base Oils from Crambe abyssinica.

Raw vegetable oil from Crambe abyssinica was subjected to oxidative treatment to enhance its viscosity. The oxidation processes were carried out in the presence of N-hydroxyphthalimide with or without supercritical CO2 as a solvent. Four spectroscopic techniques (Raman, UV-VIS, FT-IR, NMR) were applied to assess the chemical changes taking place during the oxidation. Raman and NMR spectroscopy proved best in the assessment of the chemical transformations leading to increased viscosity of the modified vegetable oil.

INTENSIFICATION OF THE CYCLOHEXANE LIQUID PHASE OXIDATION PROCESS

Liquid-phase oxidation of cyclohexane to cyclohexanol and cyclohexanone was studied in the absence of solvents under an air pressure of 0.5-5 MPa, in the temperature range 115-150 °C, catalyzed by N-hydroxyphthalimide (N-HPI). It was established for the first time that the use of N-HPI as a catalyst in place of the conventionally used metal salts of variable valence allowed a 2-3-fold increase in the conversion of the initial hydrocarbon and selectivity from 70-75 to 90%. The combined use of N-HPI with cobalt(II) acetate results in an additional increase in the conversion of cyclohexane by 30-40%, the selectivity of cyclohexanol and cyclohexanone formation to 94-97%, which seems to be due to the synergistic effect between the two components of the catalyst. The mechanism of catalytic oxidation of cyclohexane to cyclohexanol and cyclohexanone is discussed. It has been suggested that N-HPI plays a dual role in the oxidation of cyclohexane: it catalyzes the conversion of cyclohexane to cyclohexanol and cyclohexanone and, on the other hand, promotes the conversion of cyclohexanol to cyclohexanone, thereby substantially reducing the formation of adipic acid and its esters, by-products of the reaction, and increases selectivity of oxidation. This also explains the unusually high (1.3-1.5 : 1) ketone: alcohol ratio in the oxidation products of cyclohexane in the presence of N-HPI. The high selectivity of the formation of the desired products, the conversion of cyclohexane, the moderate temperature, the available catalyst, suggest that this method of oxidizing cyclohexane to cyclohexanol and cyclohexanone may be of interest for further practical use.

Designing Lubricating Properties of Vegetable Base Oils.

Lubricants that are based on renewable raw materials have drawn increased attention in various applications, especially those related to the food industry. Due to the high requirements of environmental protection, there is a need to develop biodegradable base oils that are environmentally friendly and do not contain harmful components. The objective of the research was to obtain a base oil with a certain viscosity and certain desired lubricating properties. Base oils were obtained from Crambe abyssinica oil by means of blending with synthetic oil and oxidation. The oxidation processes were carried out in the presence of N-hydroxyphthalimide with or without CO2 as a solvent. As a final result of this study, oil bases meeting the viscosity requirements and showing suitable lubricating properties were obtained. The Raman spectra of the obtained oils were evaluated.