Oxidation Of Cumene Research Articles

Catalytic properties of metals of the 2nd and 12th groups in cumene oxidation

Using kinetic modeling, a comparative study of the catalytic properties of metals of the 2nd and 12th groups (Mg, Ca, Sr, Ba, Zn, Cd, Hg) in the composition of 2-ethylhexanoates was carried out in the industrial cumene oxidation. It has been established that: 1) in terms of the combination of catalytic properties (acceleration of cumene oxidation and selectivity), it is necessary to recognize Mg and Cd to be the best: Mg accelerates the process more strongly than Cd, but Cd lowers the selectivity to a lesser extent relative to the selectivity of the non-catalytic process (the selectivity at a low initial catalyst concentration is comparable to the selectivity of a non-catalytic process); 2) the values of the accumulation rate of cumene hydroperoxide (target product) in the industrial cumene oxidation correlate with the values of the covalent atomic radii of the corresponding metals.

ANTIOXIDANT PROPERTIES OF LEAVES OF SOME TREES

ANTIOXIDANT PROPERTIES OF LEAVES OF SOME TREES

Selective electro-oxidation of cumene utilizing a flow reactor equipped with diamond electrodes

Although oxidation of benzylic C(sp3)−H bonds is an important process for synthesizing biologically active compounds, the reactions generically require hazardous reagents, catalysts, and harsh conditions. Since electro-organic synthesis utilizes electricity itself as a reagent, reactions can proceed well even under ambient conditions. Herein, we report a selective oxidation of cumene in an electrochemical flow reactor. Cumyl alcohol was selectively obtained under optimum amount of charge and current density. The selective oxidation of cumene to cumyl alcohol was achieved because overoxidation of cumyl alcohol into acetophenone was suppressed by the electrochemical flow reactor.

ANTIBACTERIAL AND ANTIFUNGAL PROPERTIES OF Zn COMPLEXES WITH N’-ACIL-SALICYLICHYDRAZIDES

The antibacterial (Pseudomonas aeruginosa and Mycobacterium phlei) and antifungal (Aspergillus niger, Penicillium Chrysogenium, Penicillium chrosegenum, Cladosporium resinae) properties of Zn complexes with the potentially tridentate (carbonyl and hydroxyl oxygen atoms of the salicylic fragment and nitrogen atom of the amide group) N'-phthalimido-salicylamide ligand and potentially heptadentate (carbonyl and hydroxyl oxygen atoms of the salicylic fragment, two nitrogen atoms of the hydrazide fragment and two oxygen atoms of the carbonyl and carboxyl groups of the maleic fragment) N'-maleoyl-salicylhydrazide ligand were studied. The antibacterial and antifungal efficacy of the samples was determined by the zonal diffusion method according to GOST 9.085-78. Meat-peptone agar (MPA) was used for growing bacterial cultures, and wort-agar (WA) was used for fungi. These studies have shown that both ligands do not show antibacterial action, but show antifungal action. Zinc complexes of these ligands exhibit both antibacterial and antifungal effects. The antimicrobial action of the complexes is much higher than that of the ligands themselves, and this action increases with an increase in the concentration of complex compounds in solution. The antioxidant effect of the compounds H2L, H4L, (H3L)2Zn, (HL)2Zn synthesized by us was studied in cumene oxidation reactions - cumene autoxidation and reactions with cumene peroxide. Establishing the mechanism of action as an inhibitor or antioxidant that prevents oxidation as a result of the presence of the above compounds was studied in the study of cumene autoxidation

Estimation of the efficiency of the C60 and C70 fullerenes as inhibitors of the radical chain oxidation of сumene

In the present work, the antioxidant efficiency of the C60 and C70 fullerenes has been quantitatively assessed with two methods: the chemiluminescence method and semilogarithmic method for processing kinetic curves based on the transformation of kinetic absorption curves at AIBN-induced cumene oxidation. As found, the measured values of the stoichiometric inhibition coefficient for C70 fullerene (f = 5.1 and 3.2) are higher than for C60 (f = 1.1 and 1.1), which indicates a higher inhibitory activity of the C70 fullerene as compared with C60. At the same time, both fullerenes demonstrate lower reactivity toward peroxyl radicals generated upon the hydrocarbon oxidation in comparison with well-known antioxidants, ionol and α-tocopherol.

Electro-conversion of cumene into acetophenone using boron-doped diamond electrodes.

A straightforward electro-conversion of cumene into acetophenone has been reported using boron-doped diamond (BDD) electrodes. This particular conversion is driven by the addition reaction of a cathodically generated hydroperoxide anion to an anodically generated cumyl cation, where the BDD’s wide potential window enables the direct anodic oxidation of cumene into the cumyl cation. Since electricity is directly employed as the oxidizing and reducing reagents, the present protocol is easy to use, suitable for scale-up, and inherently safe.

Chemical process route selection based upon potential environmental risk of chemical releases

Chemical process route selection is a key decision taken during the preliminary design stage of chemical plant development. This work presents a risk-based methodology that can be used to select the most inherently environmentally friendly chemical process route among alternate routes to produce a chemical. An index called Inherent Environmental Risk Index for Chemical Release (Chem-IERI) is proposed which represents the potential environmental risk due to a total loss of containment event in the plant. The risk index incorporates three parameters, namely the magnitude of environmental impact, the occurrence frequency of the accidental chemical release event that results in the environmental impact and the vulnerability of the environmental element where the impact is observed. Eight environmental impacts are considered and a methodology to estimate the vulnerability of environmental elements to these impacts is proposed. A higher index value indicates a higher environmental risk. The index developed was applied to assess four possible process routes to produce acetone. Propene oxidation process route showed the lowest Chem-IERI value while cumene oxidation process route showed the highest indicating the least inherent environmental friendliness.

Differentiating the {100} surfaces of Cu2O nanocrystals from {111} and {110} for benzylic Csp3-H bond oxidation: Oxidations of diphenyl methane to benzophenone and cumene to cumene hydroperoxide under mild conditions

Through this study, we have explored the basic questions like why do some facets show more photocatalytic activity towards some organic substrates resulting in photodegradation and some remain inactive at all? Do the organic reaction mechanism pathways (ionic or free radical) decide the catalyst's facets selectivity? To answer these questions, Cu2O nanocrystals (NCs) with different morphologies were synthesized by wet chemical methods. By powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM), it was confirmed that the synthesized material was Cu2O NCs with octahedral (o-Cu2O), dodecahedral (d-Cu2O) and cubic (c-Cu2O) morphologies with {111}, {110}, and {100} facets exposed, respectively. To confirm the phase purity and eliminate any probability of the presence of Cu or CuO as impurities in the material, fitting of the experimental XRD data was carried out by employing the Rietveld refinement. The synthesized Cu2O NCs with the above morphologies were employed as the catalysts for benzylic Csp3-H bond oxidation. For this purpose, a model reaction of oxidation of diphenylmethane (DPM) by using t-butyl hydroperoxide (TBHP) as an oxidant at RT was carried out in an acetonitrile medium. Out of all the morphologies evaluated, c-Cu2O NCs show the highest activity. They could complete the model oxidation reaction within 3 days with ∼99% yield and 100% selectivity for benzophenone as a sole product without any catalyst obliteration. Based on chemical kinetics experiments, electrochemical analyses, and DFT calculations, a reaction mechanism (similar to the Mars-van Krevelen reaction cycle for semiconductor metal oxide surfaces) involving (100) surfaces of c-Cu2O NCs was proposed. Furthermore, BET surface area analyses and ζ potential measurements were carried out to confirm the catalytic effect due to {100}, {111}, and {110} facets exposed. To demonstrate the efficiency of the developed oxidation protocol, industrially important oxidation of cumene to cumene hydroperoxide (CHP) was carried out under solvent-less conditions with 95% yield and 70% selectivity for CHP.

MnO2 nanoparticles supported on CNTs for cumene oxidation: Synergistic effect and kinetic modelling

Synergistic effects between the carbon materials and metal oxides usually are considered as the significant factor in the selective oxidation of hydrocarbons. In current study, MnO2/CNTs catalysts were prepared under mild condition and applied in the cumene oxidation. As high as 73.44% cumene conversion with 59.06% selectivity of 2-phenyl-2-propanol(PP) was obtained over 21.23-MnO2/CNTs, which is much higher than those of CNTs-catalysis and MnO2-catalysis systems. The decomposition of cumene hydroperoxide (CHP), a key step for cumene oxidation, was proved to be facilitated by the interaction between MnO2 nanoparticles and CNTs, which also confirmed from the DFT calculations. These results demonstrated that the synergistic effect between MnO2 nanoparticles and CNTs would greatly enhance the activity and tune the distribution of products selectivity. The kinetic modeling study in this work further revealed that the interactions between MnO2 nanoparticles and CNTs would accelerate all the elementary steps, especially, the homolytic cleavage of CHP. The reaction rate constant (k80 = 9 h−1) for 21.23-MnO2/CNTs is 450-folds of CNTs (k80 = 0.02 h−1). Moreover, the concentration distributions of acetophenone (AP) and PP were well illustrated from the kinetic study.

Prospects for the use of Zn, Cd and Hg 2-ethylhexanoates as catalysts for cumene oxidation

The effect of Zn(EH)2, Cd(EH)2 and Hg(EH)2 (EH is 2-ethylhexanoate) on cumene oxidation has been established. The use of these catalysts will make it possible to solve a number of tasks that are relevant for cumene oxidation running under industrial conditions, namely: 1) the task of reducing the oxidation time to achieve the required cumene conversion; 2) the task of increasing cumene conversion regardless of the stage of oxidation compared to non-catalytic oxidation (this will reduce the consumption of the recycle stream in the industrial process); 3) the task of accelerating cumene oxidation even in the absence of an initiator at the initial moment of time; 4) the task of maintaining the selectivity of the process even in the late stages of oxidation at a relatively low concentration of the catalyst. The most appropriate catalyst for industrial use is Cd(EH)2 because ROOH·Cd(EH)2 intermediate adduct decomposes most rapidly into free radicals.

Cumene autooxidation to cumene hydroperoxide based on a gas-liquid microdispersion strategy

Three-step Hock process is widely used in phenol industry, which suffers slow reaction speed, low efficiency, and generation of many by-products. As a key step, cumene oxidation has a significant influence on the quality of produced phenol and the process is controlled by mass transfer. Herein, aimed at enhancing cumene oxidation, microfluidics was used to strengthen the non-catalytic process. Experimental investigation with different microfluidic strategies confirmed that continuous mass transfer enhancement was of great importance for this system. When oxygen was used as the oxidant and operation at 130 °C and 0.8 MPa for 2 h, 66.2% conversion, 92.0% selectivity, and 60.9% yield were obtained, which were better than those in traditional batch reactors. The conversion was doubled while still maintaining a high selectivity of over 90%, and the reaction time was shortened to 1/4 of the original time. On the basis of the enhanced mass transfer, the kinetics of cumene oxidation was also investigated. The obtained reaction order of cumene was approximately 1.5.

Preparation of Bimetallic CuZn@mSiO2 Yolk‐Shell Catalyst for the Selective Oxidation of Cumene to Acetophenone

AbstractBimetallic catalysts have exhibited huge catalytic potential in the oxy‐functionalization of alkanes. Here, we provide a valid strategy for encapsulating copper and zinc metal oxide nanoparticles by mesoporous SiO2. The prepared CuZn@mSiO2 catalyst are yolk‐shell nanospheres with a diameter of 600 nm and a large specific surface area around 1000 m2 g−1. Bimetallic synergy between Cu and Zn was further analyzed by XRD, XPS and H2‐TPR. The selective oxidation of cumene to acetophenone was used as a probe reaction to evaluate the activity of bimetallic yolk‐shell catalysts, and the results showed excellent catalytic performance that promoted cumene to acetophenone transformation under mild conditions (80 °C, 5 h, H2O2 as oxidant). Also, the recycling tests verified the robust stability and reusability for the catalyst. Finally, a reasonable reaction mechanism was proposed to better understand the oxidation pathway of cumene.

Solid Acid Catalysts for the Hock Cleavage of Hydroperoxides

The oxidation of cumene and following cleavage of cumene hydroperoxide (CHP) with sulfuric acid (Hock rearrangement) is still, by far, the dominant synthetic route to produce phenol. In 2020, the global phenol market reached a value of 23.3 billion US$ with a projected compound annual growth rate of 3.4% for 2020–2025. From ecological and economical viewpoints, the key step of this process is the cleavage of CHP. One sought-after way to likewise reduce energy consumption and waste production of the process is to substitute sulfuric acid with heterogeneous catalysts. Different types of zeolites, silicon-based clays, heteropoly acids, and ion exchange resins have been investigated and tested in various studies. For every type of these solid acid catalysts, several materials were found that show high yield and selectivity to phenol. In this mini-review, first a brief introduction and overview on the Hock process is given. Next, the mechanism, kinetics, and safety aspects are summarized and discussed. Following, the different types of heterogeneous catalysts and their performance as catalyst in the Hock process are illustrated. Finally, the different approaches to substitute sulfuric acid in the synthetic route to produce phenol are briefly concluded and a short outlook is given.

Mno2 Nanoparticles Supported on Cnts for Cumene Oxidation: Synergistic Effect and Kinetic Modelling

Mno2 Nanoparticles Supported on Cnts for Cumene Oxidation: Synergistic Effect and Kinetic Modelling

A highly efficient transformation from cumene to cumyl hydroperoxide via catalytic aerobic oxidation at room temperature and investigations into solvent effects, reaction networks and mechanisms

Cumyl hydroperoxide (CHP) is an important intermediate for the production of phenol/acetone, but suffers from severe reaction conditions and a low yield industrially. Here, an efficient transformation from cumene to CHP was developed. Different solvents were modulated for cumene oxidation catalyzed by NHPI/Co, and reaction network and mechanisms were investigated methodically. Hexafluoroisopropanol (HFIP) markedly promoted the transformation from cumene to CHP compared to other solvents at room temperature. A cumene conversion high up to 64.3% were observed with a selectivity to CHP of 71.7%. The solvent HFIP exhibited a significant promotion on cumene oxidation due to its contribution to the enhancement of the concentration of PINO radicals. Moreover, cumyl, cumyl oxyl and methyl radicals were captured by TEMPO and analyzed by HRMS, and the reaction paths and mechanisms from cumene to products were inferred. The preparation method discovered in this work may open an access to the production of CHP.

A green catalyst-free concomitant air oxidation of DMSO and cumene to form methylsulfonylmethane (dimethylsulfone)

Methylsulfonylmethane (MSM) is a newly discovered human nutrient that has significant health care and therapeutic function. In this work, we developed a new type of catalyst-free air oxidation of dimethyl sulfoxide (DMSO) to MSM under relatively mild conditions based on the mechanism of isopropylphenyl free radicals (R·) activating molecular oxygen (O2) generating reactive oxygen species (ROS). Experimental results showed that cumene as a solvent, due to its active tertiary sp3 C–H bond, promotes the efficient catalyst-free air oxidation of DMSO to MSM under relatively mild optimized conditions. Based on the quenching test of free radicals and theoretical calculation of the activation energies of two oxidation pathways of isopropylphenyl peroxy radicals (ROO·) and cumene hydroperoxide (CHP), it has been demonstrated that ROS in this reaction is mainly ROO· and hydroxyl radicals (HO·). Furthermore, we proposed a possible catalyst-free air oxidation mechanism. This work provided a simple and cost-efficient approach for the green synthesis of MSM.

The influence of Fe(III) acetylacetonate and o-phenanthroline towards improvement of NHPI-catalyzed cumene oxidation

Cumene hydroperoxide (CHP) is the most important product or intermediate in the oxidative processing of cumene. In the present study, cooperative action of NHPI catalyst with Fe(acac)3/Phen additives in oxidation of cumene has been described in terms of oxidation rate and selectivity for products, notably CHP, under variable conditions. The oxidation characteristics were influenced by promoting additives, the main function of which was to generate an active PINO radical. An abundance of the additives might enhance the non-selective conversion of intermediates and decomposition of CHP, which led to a decrease in CHP selectivity. The addition of 0.0003 mol% Fe(acac)3 was sufficient to initiate NHPI catalyzed fast cumene oxidation and very selective CHP production at 50 °°C. Phen showed an impressive multifaceted effect, as the increase in its amount initially lowered the CHP selectivity and then increased to 95% with a large excess of Phen over Fe(acac)3. That was due to the different ability of iron complexes of various compositions to react to NHPI and to CHP. UV-VIZ spectroscopy and DFT calculation was used to elucidate assistance of Phen in reduction of Fe(acac)3 with NHPI and creation of FeII/FeIII –Phen2or3 complexes as reversible single-electron carriers upon catalysis by NHPI. In addition, the selective formation of CHP contributes to the resistance of NHPI to degradation during catalysis.

The cumene oxidation and cumene hydroperoxide decomposition in the presence of Zn, Cd or Hg 2-ethylhexanoate: Kinetic model and analysis of its sensitivity

A general kinetic model for industrially significant cumene oxidation and cumene hydroperoxide decomposition in the presence of Zn, Cd or Hg 2-ethylhexanoate as catalyst was developed. The model was based on the mass action law, in the form of a stiff system of nonlinear differential equations describing the rates of change in the concentrations of all species in the reaction mixture during the processes. Physically substantiated values of the unknown coefficients of the model (the coefficients of the temperature dependencies of the reaction rate constants) were found as a result of solving the inverse problem. It was done by minimizing the average relative error (using the method of direct search of the zero order) between the data calculated as a result of the numerical solving of the model by the implicit BDF method and the experimental data. The analysis of model sensitivity to changes of its coefficients has been carried out. Through this analysis, the original model is reduced to a simplified form, more convenient for studying the kinetic regularities and the mechanism of the considered chemical processes. The modification of the original model involved in exception from its equations of the terms containing the coefficients that were found as a result of solving the inverse problem, for which change the model is insensitive. A total of 39 terms were excepted out of 179. Thus, a possible mechanism for the cumene oxidation and cumene hydroperoxide decomposition in the presence of Zn, Cd or Hg 2-ethylhexanoate has been substantiated. The developed model was used to study the catalytic activity and thermal stability of Zn, Cd and Hg 2-ethylhexanoates in cumene oxidation and cumene hydroperoxide decomposition. Computational experiments have shown that the catalytic activity of Zn, Cd and Hg 2-ethylhexanoates in cumene oxidation and cumene hydroperoxide decomposition is caused by formation of intermediate adducts ROOH⋅Cat, which turn to be an additional source of free radicals due to their lower thermal stability compared to the original catalyst and cumene hydroperoxide. This phenomenon can be used for practical purposes to increase the rate of cumene hydroperoxide accumulation during cumene oxidation. The kinetic model presented in the article, can be a starting point (model object) for the development of kinetic models of oxidation processes of other aromatic hydrocarbons, catalyzed by nontransition metals due to the formation of intermediate adducts.

Inhibitory effect of Zn2+ on the chain‐initiation process of cumene oxidation

AbstractCarbon nanotubes (CNTs) have excellent catalytic activity in liquid phase reaction, especially in aerobic oxidation of cumene. In previous work, the conversion of cumene was 41.8% and the selectivity of cumene hydroperoxide was 71.5%, which was catalyzed by CNTs. But a small amount of impurity Zn2+ totally blocked up the aerobic oxidation of cumene that catalyzed by CNTs, which is an unexpected discovery. By analyzing the catalytic mechanism of CNTs, the inhibition effect of Zn2+ is locked on the abstraction of H atom from cumene. The inhibition of Zn2+ is confirmed in two effects by density functional theory calculations. First, due to the strongly coordination of active oxygen species (ROS) by Zn2+, the energy barrier of initial reaction increases to 1.90 eV, which is nearly 4 times higher than that of the only ROS promoted‐process. Second, the interaction of Zn2+ and RO· or ROO· to inhibits the chain propagation reaction of free radicals. This work precisely demonstrates that the inhibition effect of Zn2+ on initial reaction of cumene. The most significant thing is that the effect of metallic heteroatoms is not negligible in organic oxidation reaction.

Supported transition metals oxides and N-hydroxyphthalimide as binary catalytic systems for the liquid-phase oxidation of cumene

• Transition metal oxide (TMO) activates NHPI molecule producing PINO • radical • Surface acidity and redox properties of the metal oxide catalyst influence activation of NHPI • PINO • radical activated at the surface initiates/propagates homogeneous oxidation • Synergistic effect of NHPI-TMO couple increases oxidation rate • The efficiency of TMO as a cocatalyst decreases in order V 2 O 5 ≈ MnO x > CuO x The heterogeneous catalysts based on single active component such as V 2 O 5, MnOx and CuOx and bi-components V 2 O 5 -MoO 3 V 2 O 5 -WO 3 and V 2 O 5 -SbO x supported onto TiO 2 , TiO 2 -SiO 2 and Al 2 O 3 -SiO 2 was prepared and characterized. The aerobic liquid-phase oxidation of cumene (RH) in the presence of binary catalytic system containing N-hydroxyphthalimide (NHPI) and supported V, Mn and Cu oxides has been studied. It was observed that catalytic activities of the mono metallic systems decreases in order V 2 O 5 ≈ MnO x > CuO x , bi-metallic catalysts showed no catalytic activities. The effect of catalytic system composition comprising MnO x or VO x and NHPI, AIBN on the oxidation rate was studied . The major oxidations product was cumene hydroperoxide, whereas dimethyl phenyl carbinol and acetophenone were found as minor ones. The reactions scheme that summarizes the oxidation chemistry identifying the related role of heterogeneous initiation and homogeneous propagation and termination steps for oxidation of cumene via free-radical mechanism are presented.