Di-tert-butyl Peroxide Research Articles

Initiator-introduced heavy oil visbreaking in supercritical benzene

The performance of introducing a free radical initiator into dealkylation-based visbreaking of heavy oil in the N2 or supercritical benzene (SCbenzene) medium was investigated. Calculations based on density functional theory show that the introduction of di-tert-butyl peroxide (DTBP) into heavy oil visbreaking results in the formation of alkyl C radicals similar to those naturally formed in high temperature initiation. The visbreaking in SCbenzene environment is sensitive to the introduction of DTBP, which is different from the visbreaking in N2 environment. According to reaction kinetics analysis, the presence of SCbenzene solvent and the introduction of DTBP greatly accelerate the dealkylation related lumped reactions. Benefiting from improved diffusion environment, the superimposed radicals resulting from DTBP introduction effectively participate in visbreaking and selectively accelerate dealkylation. After only 10–20 min of reaction at 380 °C, visbreaking products with satisfactory viscosity reduction, reduced asphaltene content and improved light component yield can be obtained.

Transition‐Metal‐Free Radical Cyclization of 2‐Arylbenzoimidazoles with Unactivated AlkanesviaC(sp3)−H Functionalizations in Aqueous Media

AbstractHere we present a transition‐metal‐free radical cyclization of 2‐arylbenzoimidazoles with unactivated alkanes. By using di‐tert‐butyl peroxide (DTBP) to promote the C(sp3)−H bond functionalization, this approach enables assembly of various benzimidazo[2,1‐a]isoquinolin‐6(5H)‐ones in aqueous media. This strategy can not only well tolerate a wide range of cyclic alkanes, straight‐chain alkanes, toluene derivatives, as well as pharmaceutical molecule eudesmol, but also provides an approach for the functionalization of unactivated C(sp3)−H bonds in aqueous media under transition‐metal‐free systems.magnified image

Efficient Oxidation of Cyclohexane over Bulk Nickel Oxide under Mild Conditions.

Nickel oxide powder was prepared by simple calcination of nickel nitrate hexahydrate at 500 °C for 5 h and used as a catalyst for the oxidation of cyclohexane to produce the cyclohexanone and cyclohexanol—KA oil. Molecular oxygen (O2), hydrogen peroxide (H2O2), t-butyl hydrogen peroxide (TBHP) and meta-chloroperoxybenzoic acid (m-CPBA) were evaluated as oxidizing agents under different conditions. m-CPBA exhibited higher catalytic activity compared to other oxidants. Using 1.5 equivalent of m-CPBA as an oxygen donor agent for 24 h at 70 °C, in acetonitrile as a solvent, NiO powder showed exceptional catalytic activity for the oxidation of cyclohexane to produce KA oil. Compared to different catalytic systems reported in the literature, for the first time, about 85% of cyclohexane was converted to products, with 99% KA oil selectivity, including around 87% and 13% selectivity toward cyclohexanone and cyclohexanol, respectively. The reusability of NiO catalyst was also investigated. During four successive cycles, the conversion of cyclohexane and the selectivity toward cyclohexanone were decreased progressively to 63% and 60%, respectively, while the selectivity toward cyclohexanol was increased gradually to 40%.

Chemo- and regioselective benzylic C(sp3)–H oxidation bridging the gap between hetero- and homogeneous copper catalysis

SummarySelective C‒H functionalization in a pool of proximal C‒H bonds, predictably altering their innate reactivity is a daunting challenge. We disclose here, an expedient synthesis of privileged seven-membered lactones, dibenzo[c,e]oxepin-5(7H)-one through a highly chemoselective benzylic C(sp3)‒H activation. Remarkably, the formation of widely explored six-membered lactone via C(sp2)‒H activation is suppressed under the present conditions. The reaction proceeds smoothly on use of inexpensive metallic copper catalyst and di-tert-butyl peroxide (DTBP). Owing to the hazards of stoichiometric DTBP, further, we have developed a sustainable metallic copper/rose bengal dual catalytic system coupled with molecular oxygen replacing DTBP. A 1,5-aryl migration through Smiles rearrangement was realized from the corresponding diaryl ether substrates instead of expected eight-membered lactones. The present methodology is scalable, applied to the total synthesis of cytotoxic and neuroprotective natural product alterlactone. The catalyst is recyclable and the reaction can be performed in a copper bottle without any added catalyst.

The effect of temperature and peroxides content on cross-linking and properties of EPDM-based rubber matrix

In this work, dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP), di(tert-butylperoxyisopropyl)benzene (DTBPIB), and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (DDTBPH) were used for cross-linking of rubber matrix based on Ethylene-propylene-diene monomer rubber (EPDM). The aim was to investigate the influence of curing temperature and the type and content of peroxide on curing process of rubber compounds, cross-link density, and physical-mechanical properties of vulcanizates. The results revealed that higher curing temperatures promote faster decomposition of organic peroxides, leading to the faster reactions of peroxide radicals with rubber chains. The increase in temperature resulted also in the increase of cross-linking degree. Although, side reactions as chain scission take over the main cross-linking reactions at very high temperatures resulting in the decrease of cross-link density. The increasing content of peroxides resulted in the acceleration of curing reactions and to increase of cross-link density. The fastest curing kinetics exhibited rubber compounds cured with DCP. However, vulcanizates cured with DCP were found to have the lowest cross-link density. In generally, the dependences of modulus, hardness, and elongation at break of vulcanizates were in line with the dependences of the cross-link densities, while higher tensile strength were found to have vulcanizates cured at higher temperatures and lower peroxides content.

Visible‐Light‐Driven di‐t‐Butyl Peroxide‐Promoted the Oxidative Homo‐ and Cross‐Coupling of Phenols

AbstractThe visible‐light‐induced oxidative homo‐ and cross‐coupling of phenols by di‐t‐butyl peroxide (DTBP) are described. These reactions occur with metal‐free process and feature high chemo‐ and regioselectivity under mild reaction conditions. DTBP is an inexpensive, benign, stable at room temperature, and commercially available oxidizer. It can be irradiated by blue LEDs to generate tert‐butoxyl radical (tBuO⋅), which induces the oxidative homo‐coupling of phenols and the cross‐coupling of phenols with naphthols, respectively.

Controlled preparation of PAMS hollow core microcapsules with high uniformity and its application in the production of GDP fuel capsules for ICF engineering

Uniform poly-α-methylstyrene (PAMS) hollow core microcapsules (HCMs) are widely used as templates to fabricate glow discharge polymer (GDP) fuel capsules, which are fundamental devices for inertial confinement fusion (ICF) engineering. The sphericity and surface finish uniformity of PAMS HCMs are critical for achieving high-quality GDP fuel capsules. In this work, millimeter-scale PAMS HCMs were fabricated by a microencapsulation technique. The sphericity and surface finish uniformity were concurrently improved using di-t-butyl peroxide (DTBP). The mechanisms of these effects were also experimentally and theoretically investigated. The results show that DTBP distributes at the O-W2 interface of W1/O/W2 compound droplets, which resists the diffusion of molecules through the O-W2 interface bidirectionally. The resisted diffusion of H2O molecules into the O phase eliminates PAMS HCM surface defects. Additionally, the resistance of fluorobenzene (FB) molecules from diffusing from the O phase into the W2 phase can effectively extend the solidification of W1/O/W2 compound droplets and thus improve the spherical uniformity of the HCMs. Using these improved PAMS HCMs, GDP fuel capsules meeting the stringent requirements for ICF engineering are prepared, and the quality of which is beyond the National Ignition Facility standard.

Temperature distribution and pressure oscillation characteristics of di-tert-butyl peroxide overpressure relief in a confined space

Pressure relief can effectively reduce the damage caused by the thermal runaway reaction of organic peroxides in the chemical process. To further understand the overpressure relief mechanism of di- tert -butyl peroxide (DTBP), pressure vessel test system and numerical simulation method were combined to systematically analyze the dynamic relief characteristics of DTBP in a confined space. The three-dimensional spatial distribution and variation law of temperature, pressure, and airflow velocity during the relief process were also revealed. The results show that a high-speed under-expanded jet is generated when DTBP overpressure relief occurs, and low temperature and negative pressure are produced inside the vessel and near the vent. The airflow velocity first increases and then decreases during the relief process, with a maximum value of 487 m/s. Both the internal temperature and pressure show prominent damping oscillation characteristics, and the oscillation period is between 2.1 ms and 2.3 ms. The pressure oscillation curves at different positions present different peak shapes, and the closer to the vent, the smaller the pressure amplitude. The consistency between the experimental results and simulation data also verifies the reliability of the numerical model.

Analytical pyrolysis of jet fuel using different free radical initiators to produce low molecular weight hydrocarbons

Employing endothermic hydrocarbon fuels in high speed flights aids in regenerative cooling of the aircraft surfaces and components due to the physical and chemical heat sink mechanisms they offer. The development of such fuels involves a thorough understanding of its pyrolysis characteristics in the presence of additives. In this study, analytical Curie point pyrolyzer is used to conduct pyrolysis of Jet-A1 fuel, and investigate the effect of temperature and free radical initiators on the pyrolysate composition. The temperatures were 590 °C, 740 °C and 920 °C, and the initiators were triethylamine (TEA), 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), phenyl hydrazine (PH), 1-nitropropane (NP), di-tert-butyl peroxide (DTBP), and cumene hydroperoxide (CH). The results showed that, at 590 °C, the addition of TEMPO, NP and PH, all at 5 wt% to the fuel, improved the cracking reactions with 25% decline in yield of alkanes compared to pyrolysis of neat Jet-A1. It was also observed that the yield of alkyl-substituted benzenes was high in presence of TEMPO and PH, while the yield of iso-alkanes was high in the presence of DTBP, CH and TEA. At 920 °C, the yield of low molecular weight alkenes (C3-C7) was high with TEMPO (11.6%) followed by PH (6.8 wt%), TEA (6.7 wt%) and NP (6.5 wt%). The plausible reactions occurring in the presence of initiators are discussed by thoroughly analyzing the pyrolysates.

Thermal hazards and initial decomposition mechanisms study of four tert-butyl organic peroxides combining experiments with density functional theory method

Thermal hazards and initial decomposition mechanisms of di-tert-butyl peroxide (DTBP), tert-butyl cumyl peroxide (TBCP), tert-butyl peroxy benzoate (TBPB) and tert-butyl peroxy-2-ethylhexanoate (TBPEH) were comprehensively studied. Activation energies of the four tert-butyl organic peroxides (TBOPs) were obtained by differential scanning calorimetry (DSC) experiments and kinetic analysis methods. Adiabatic thermal decomposition characteristic parameters were obtained by accelerating rate calorimeter (ARC) and thermal risk was evaluated by matrix assessment. Thermal decomposition products were determined by gas chromatography-mass spectrometry (GC-MS) experiments and decomposition pathways were proposed according to the analytical results. The energy of each step of the proposed pathways was calculated by density functional theory (DFT) method. The results indicated that all of the four TBOPs were divided into class Ⅲ unacceptable hazard. Acetone was the main decomposition product of the four TBOPs. The most likely decomposition step to generate acetone was that the tert-butane oxygen radical detached a methyl. The main pathway was determined by comparing the energy barrier of rate-determining step. This work provided helpful suggestions for the safe application of the four TBOPs in the practical chemical process.

Influence of injection timing on performance and combustion characteristics of compression ignition engine working on quaternary blends of diesel fuel, mixed biodiesel, and t-butyl peroxide

The objective of the present work is to examine the effects of adding t-butyl peroxide (TB) additive with diesel fuel and biodiesel originated from Mahua oil and waste Palm oil in form of quaternary blends with varying injection timing (21obTDC (before Top Dead Centre), 23obTDC, and 25obTDC) on performance, emission, and combustion characteristics of a diesel engine. In this experimentation, all the quaternary blends were prepared by keeping the volume percentage of diesel fuel at 50% v/v, while concentrations of Mahua oil-based biodiesel, waste Palm oil-based biodiesel, and t-butyl peroxide were varied by volume. The prepared blends were utilized on a constant-speed single-cylinder 4-stroke turbocharged diesel engine for comprehensive analysis in contrast to diesel fuel. The obtained results depicted that the quaternary blend of 50% diesel fuel (D)/20% mixed biodiesel (MB)/30% t-butyl peroxide (TB) (D50-MB20TB30) at advanced injection timing of 25°bTDC has shown a 2.66% increment in exhaust gas temperature and a 2.12% reduction in brake thermal efficiency compared to diesel fuel. At peak load, emission parameters such as carbon monoxide, unburnt hydrocarbon, and smoke opacity for D50-MB20TB30 were found to be respectively 4.59%, 3.47% and 5.03% lower than those of diesel fuel, although there was a slight increment by 0.83% of nitrogen oxide compared to diesel fuel. Considering combustion behaviours, heat release rate, cylinder pressure, and ignition delay were also observed to be 1.14%, 2.21%, and 8.34% lesser than conventional diesel fuel at 100% load, respectively. In closing, using the D50-MB20TB30 quaternary blend combined with advanced injection timing of 25°bTDC could offer a significant efficiency in improving the engine performance and reducing pollutant emissions, contributing to sustainable development and environment protection.

Adiabatic kinetics calculations considering pressure data

Pressure and temperature play an important role in the adiabatic decomposition of hazardous materials. In this article, Accelerating Rate Calorimeter (ARC) was used to study adiabatic decomposition of 40 wt% dicumyl peroxide (DCP) solution，20 wt% di-tert-butyl peroxide (DTBP) solution and 2,4-dinitrotoluene (2,4-DNT). Based on the temperature and pressure signals, the kinetic constants of 40 wt% DCP and20 wt% DTBP were calculated separately. It is found that the temperature and gas production kinetics of the 40 wt% DCP solution are in good agreement with each other, but the temperature and gas production kinetics of 20 wt% DTBP solution are significantly different. The adiabatic decomposition of 2,4-DNT under different pressure conditions was experimentally investigated. The experimental results indicated that pressure promoted the adiabatic decomposition of 2,4-DNT. Accordingly, new kinetic equations were developed to describe the adiabatic decomposition of 2,4-DNT under different pressure conditions. These works provide a new insight into adiabatic kinetics calculations.

Synthesis and application of SBA-15-supported CuO as an efficient catalyst for the oxidative C(sp2)-O coupling reaction

SBA-15-supported CuO was synthesized via wet impregnation of SBA-15 with copper (II) acetylacetonate followed by calcination in the static air. The BET surface area of the Cu-containing SBA-15 was approximately 600 m2/g, which significantly decreased in comparison with that of as-synthesized SBA-15 silica (1081 m2/g). The successful loading of copper with a 3.20 wt.% content was determined by ICP-OES analysis, consistent with theoretical composition. However, no Cu-based phases were detected on the PXRD results and TEM images for CuO/SBA-15 showed regular hexagonal meso channels remained, indicating that CuO species was well distributed in the SBA-15 framework via the applied synthetic procedure. Catalytic activity of SBA-15-supported CuO was investigated for the selective C(sp2)-O coupling reaction between salicylaldehyde and N, N-dimethylformamide (DMF) in the presence of di-tert butyl peroxide (DTBP) as an oxidant. Influence of the reaction conditions on the formation of desired product was studied including reaction time, temperature, reactant ratio, amount of catalyst and oxidant. The experimental results proved that the high activity of the prepared catalyst as the C(sp2)-O coupling product could be obtained in an excellent yield of 90% with only 3 mol% of SBA-15-supported CuO in the presence of 4 equivalents of DTBP at 120 °C in 2 hours.

Di-tert-butyl peroxide (DTBP)-mediated synthesis of symmetrical N,N′-disubstituted urea/thiourea motifs from isothiocyanates in water

ABATRACT A direct approach to N,N′-disubstituted urea/thiourea from the self-condensation reactions of isothiocyanates in water has been developed. This access tolerated a wide range of functional groups on the aromatic ring, providing a practical and environment-friendly process to N,N′-disubstituted urea/thiourea in moderate to excellent yields from safe and easily available starting materials. A plausible mechanism of the desulfurization self-condensation reaction for urea was also proposed and the role of di-tert-butyl peroxide (DTBP) and copper catalyst in the present strategy was demonstrated with the help of ESI mass spectrometry of intermediate studies.

Influence of Newly Organosolv Lignin-Based Interface Modifier on Mechanical and Thermal Properties, and Enzymatic Degradation of Polylactic Acid/Chitosan Biocomposites.

This article aimed to study the effects of chitosan fiber and a newly modifying agent, based on organosolv lignin, on mechanical and thermal performances and the enzymatic degradation of PLA/chitosan biocomposites. A newly modifying agent based on polyacrylic acid-grafted organosolv lignin (PAA-g-OSL) was synthesized via free radical copolymerization using t-butyl peroxide as the initiator. The biocomposites were prepared using an internal mixer and the hot-pressed method at various fiber loadings. The results demonstrate that the addition of chitosan fiber into PLA biocomposites remarkably decreases tensile strength and elongation at break. However, it improves the Young’s modulus. The modified biocomposites clearly demonstrat an improvement in tensile strength by approximately 20%, with respect to the unmodified ones, upon the presence of PAA-g-OSL. Moreover, the thermal stability of the modified biocomposites was enhanced significantly, indicating the effectiveness of the thermal protective barrier of the lignin’s aromatic structure belonging to the modifying agent during pyrolysis. In addition, a slower biodegradation rate was exhibited by the modified biocomposites, relative to the unmodified ones, that confirms the positive effects of their improved interfacial interaction, resulting in a decreased area that was degraded through enzyme hydrolysis.

Evaluating the outcomes of a single-cylinder CRDI engine operated by lemon peel oil under the influence of DTBP, rice husk nano additive and water injection

In the search for an alternative energy source with lesser pollution for transportation needs, bio-oil, a denser and viscous fuel that needs a transesterification process, have been widely considered for diesel engines. However, these problems are solved by using low viscous biofuel, but this improvement also significantly leads to increased NOx emission. Hence this present study investigates the usage of a low viscous biofuel in the CRDI engine with measures to reduce NOx emission through water injection technique. The low viscous bio-oil was used in this study along with an ignition enhancer (di-tert-butyl-peroxide), non-metallic nano additive (rice husk). They were tested in a constant speed, single-cylinder, diesel engine for various loads. Considering the brake thermal efficiency (BTE), 2% and 150 ppm were selected as the optimum value after testing five ratios (1%, 1.5%, 2%, 2.5% and 3%) of di tert butyl peroxide (DTBP) and four ratios (50, 100, 150 and 200 ppm) of rice husk (RH). The lemon peel oil (LPO) with the optimum additive ratio produced 30.69% BTE, which was 4.7% lesser than diesel fuel. A considerable decrease in fuel consumption and emissions except for nitrogen oxides (NOx) is recorded. NOx emission increased by 17.3% for the biofuel blend containing RH and DTBP. To control NOx emission, 2% of water was injected into the intake manifold with the fresh intake air. Two percent by vol. was finalised after experimenting four ratios (1%, 2%, 3% and 4%) of water addition. This 2% water reduces 11% of NOx emission and affects the other outputs, denoted with the 8.9% reduced BTE value compared with diesel fuel. Thus, the LPOC combination proved to operate well in the CRDI engine and produces lower NOx emissions than other LPO blends.

Prediction-Optimization of the Effects of Di-Tert Butyl Peroxide-Biodiesel Blends on Engine Performance and Emissions Using Multi-Objective Response Surface Methodology

Abstract Alternative fuels, such as biodiesel, can be used in place of fossil fuels, although they have a greater viscosity and a longer igniting delay. To compensate for these limitations, several additives are added to biodiesel. The cetane improver di-tert butyl peroxide (DTBP) was investigated as an additive in this work. DTBP was shown to influence the combustion and emission properties of waste cooking oil biodiesel-diesel blends. The multi-objective response surface technique (MORSM) with Box-Behnken design was used to decrease the number of trials to conserve precious resources such as human effort, time, and money. Theil's uncertainty for the model's predictive capabilities (Theil's U2) was less than 0.1189, demonstrating its robustness. Nash-Sutcliffe efficiency was excellent (0.9885–0.9995), with a mean absolute percentage error of less than 1.32%. The engine operating parameters that were optimized were 71.64% engine load, 4964 ppm DTBP additive, and 24.98-deg advance ignition timing. The MORSM-based proposed technique's reliability and robustness validate the usage of DTBP with biodiesel blends, model prediction, and optimization.

Novel Thiol Containing Hybrid Antioxidant-Nitric Oxide Donor Small Molecules for Treatment of Glaucoma.

Oxidative stress induced death and dysregulation of trabecular meshwork (TM) cells contribute to the increased intraocular pressure (IOP) in primary open angle (POAG) glaucoma patients. POAG is one of the major causes of irreversible vision loss worldwide. Nitric oxide (NO), a small gas molecule, has demonstrated IOP lowering activity in glaucoma by increasing aqueous humor outflow and relaxing TM. Glaucomatous pathology is associated with decreased antioxidant enzyme levels in ocular tissues causing increased reactive oxygen species (ROS) production that reduce the bioavailability of NO. Here, we designed, synthesized, and conducted in vitro studies of novel second-generation sulfur containing hybrid NO donor-antioxidants SA-9 and its active metabolite SA-10 to scavenge broad-spectrum ROS as well as provide efficient protection from t-butyl hydrogen peroxide (TBHP) induced oxidative stress while maintaining NO bioavailability in TM cells. To allow a better drug delivery, a slow release nanosuspension SA-9 nanoparticles (SA-9 NPs) was prepared, characterized, and tested in dexamethasone induced ocular hypertensive (OHT) mice model for IOP lowering activity. A single topical eye drop of SA-9 NPs significantly lowered IOP (61%) at 3 h post-dose, with the effect lasting up to 72 h. This class of molecule has high potential to be useful for treatment of glaucoma.

Sunlight-induced C[sbnd]C bond formation reaction: Radical addition of alcohols/ethers/acetals to olefins

A sunlight-induced CC bond formation reactions upon the addition of alcohols/ethers/acetals to olefins proceeded efficiently using di-tert-butyl peroxide (DTBP). The reactions proceeded faster than many of the previously reported sunlight and many conventional lamp photolyses, typically in 3–4 h under irradiation with sunlight, in excellent yield using olefins bearing two electron withdrawing groups (EWGs) (product yield > 95 %) and in good to fair yield with olefins bearing one EWG. The yields observed for some products were ∼20 % higher than those obtained using a conventional Xe lamp as the light source, which was confirmed to be due to a light intensity effect. Gram-scale experiments showed similar yields to those observed in their corresponding small-scale experiments.

Highly Efficient Copper-Catalyzed Dehydrogenative Cross-Coupling of Azoles with α-Amino Carbonyl Compounds

AbstractA novel and highly efficient dehydrogenative cross-coupling­ reaction between α-amino carbonyl compounds and azoles by copper catalysis using di-tert-butyl peroxide (DTBP) as an oxidant is described­. A diverse range of azoles undergo the dehydrogenative imidoylation smoothly with various α-amino carbonyl compounds for the exclusive formation of the corresponding N-imidoyl azoles in high yields under air. The synthetic method has the advantages of good functional-group tolerance, wide substrate scope, excellent yields, and simple operation­, thus providing a convenient and practical protocol for the synthesis of functionalized azoles.