Non-catalytic Reaction Research Articles

Production of biodiesel from non-edible industrial oilseeds via non-catalytic transesterification

The non-catalytic conversion of non-edible biomass into biodiesel (BD) is the subject of this investigation. Conventional oil extraction from biomass often results in economic and technical inefficiencies. This study suggests a non-catalytic transesterification reaction to directly convert castor seeds into BD in order to overcome these problems. Base-catalysed transesterification of extracted castor seed oil had a BD yield of 84.43 wt% (reaction time: 24 h at 60 ˚C). In contrast, non-catalytic transesterification of castor seed oil produced a BD yield of 93.79 wt%, which completed the reaction in 1 min at 390 ˚C. Thus, using the non-catalytic transesterification approach, we were able to empirically verify the greater conversion efficiency of BD. Additionally, the direct non-catalytic conversion of castor seed to BD achieved a yield of 105.81 wt%, suggesting that substantial oil loss occurs during the extraction process. These findings suggest that the traditional method of converting BD, which involves oil extraction and base-catalysed transesterification, is less efficient and less financially advantageous than directly converting castor seeds into BD.

NO Emission Characteristics of Pulverized Coal Combustion in O2/N2 and O2/H2O Atmospheres in a Drop-Tube Furnace.

Oxy-steam combustion is a new oxy-fuel combustion technology. This paper focuses on the NO emission characteristics during the combustion of SF (Shen Fu) coal in O2/N2 and O2/H2O mixtures. Experiments were performed in a drop-tube furnace. Combustion tests were carried out in O2/N2 and O2/H2O atmospheres for various O2 concentrations (21%, 30%, 40%, and 60%) at different temperatures (1173 K, 1273 K, and 1373 K). In addition, combustion experiments at different excess oxygen ratios (λ) were conducted in O2/N2 and O2/H2O atmospheres. The influences of the atmosphere, oxygen concentration, temperature, and excess oxygen ratio on NO emissions were analyzed. The results show that the NO concentrations of SF coal combustion in the 21% O2/79% H2O atmosphere were much lower than those in the 21% O2/79% N2 atmosphere at the three temperatures considered. This was because a large amount of NO was decomposed during the SF coal combustion in the O2/H2O atmospheres. The reasons for the decomposition of NO include the selective non-catalytic reaction (SNCR) mechanism and char's important role as a catalyst for the destruction of NO, either directly or by reacting with CO or H2. In oxy-steam combustion, the NO concentrations significantly increased with the increase in the oxygen concentration from 21 vol.% to 60 vol.% and the temperature from 1173 K to 1373 K. The excess oxygen ratio (λ) slightly impacted the NO emissions in the O2/H2O atmosphere.

Novel Determination of Functional Groups in Partially Acrylated Epoxidized Soybean Oil.

The acrylation degree of vegetable oils plays a relevant role in determining the mechanical properties of the resulting polymers. Both epoxide and acrylate functionalities participate in polymerization reactions, producing various types of chemical bonds in the polymer network, which contribute to specific properties such as molecular size distribution, crosslinking degree, and glass transition temperature (Tg). The accurate identification of epoxide and acrylated groups in triglyceride molecules helps to predict their behavior during the polymerization process. A methodology based on analytical spectrometric techniques, such as direct infusion, mass spectrometry with electrospray ionization, and ultra-high-performance liquid chromatography, is used in combination with FTIR and 1H NMR to characterize the epoxy and acrylic functionalities in the fatty chains with different numbers of carbon atoms of partially acrylated triglycerides obtained by a non-catalytic reaction.

Catalytic hydrothermal liquefaction of Azolla filiculoides into hydrocarbon rich bio-oil over a nickel catalyst in supercritical ethanol

Hydrothermal liquefaction (HTL) is one of the most promising thermochemical techniques for converting wet biomass into crude oil-like products (bio-oil). In this study, Catalytic hydrothermal liquefaction of Azolla filiculoides (AZ) was performed over a various loading of nickel (Ni) on magnesium oxide (MgO) catalyst for the higher and quality bio-oil production. The key operating parameters such as temperature, reaction holding time, amount of Ni on MgO supports catalyst, and reaction solvents were investigated in the presence of a hydrogen environment. There was a 12.8 wt% increase in bio-oil yield and a 6.3 wt% decrease in biochar yield with addition of 15 wt% Ni catalysts compared to the non-catalytic reaction bio-oil yield (44.0 wt%). Results confirmed the highest total bio-oil yield of 56.8 wt% was attained at 280 °C with the catalyst amount of 15 wt% at a residence time of 45 min. Gas chromatography-mass spectrometry (GC-MS), FT-IR, CHNS, TGA, and NMR analyses were performed on the bio-oil, identifying 32.8 % long-chain hydrocarbons (C12-C16) along with small amounts of alcohols, alkanes, and esters. The boiling point distribution revealed that bio-oil produced using the Ni/MgO catalyst contained a significantly higher proportion of diesel-range hydrocarbons (42.4 %). Furthermore, the bio-oil yield under ethanol solvent and Ni catalysts showed higher heating value (HHV) 42.2 MJ/kg. Overall in the presence of Ni hydrogenation efficient catalysts on MgO in the liquefaction reaction promoted the deoxygenation and hydrogenation reaction.

Catalytic and non-catalytic reactions of methane pyrolysis for hydrogen production in screening and electromagnetic levitation reactors using computational fluid dynamics

Molten metal (MM)-based methane (CH4) pyrolysis is a promising technology for clean hydrogen production with a minimal carbon footprint. Electromagnetic levitation (EMLR) and screening reactors (SR) were used to investigate the intrinsic catalytic reaction kinetics of MM-based CH4 pyrolysis. Heterogeneous catalytic reactions in the SR and EMLR occurred on the surfaces of the MM crucible and droplet, respectively. However, a homogenous non-catalytic reaction may occur just above the surface because the CH4 gas is preheated by the high-temperature MM. This study presents three-dimensional (3D) computational fluid dynamics (CFD) model coupled with chemical reactions to assess the extent to which non-catalytic reactions intervene in CH4 pyrolysis in both the SR and EMLR, which is difficult to measure experimentally. The CFD model validated against experimental data revealed that the non-catalytic reaction accounted for 4.0 % of CH4 pyrolysis in the CH4-Ni0.27Bi0.73 SR at 1045 °C, whereas it represented 0.02 % in the CH4-Sn EMLR at 1021 °C. This result highlights that the EMLR is suitable for studying the intrinsic catalytic reaction kinetics of MM-based CH4 pyrolysis because the non-catalytic reaction occurs to a lesser extent.

Application of KF/waste glass catalyst in the synthesis of fatty acid esters under pressurized conditions without glycerol generation

In this study, the efficiency of applying the KF/waste glass catalyst was tested in the transesterification of crambe oil under pressurized conditions for the synthesis of esters and glycerol carbonate (GLC). For this, a miscella pressurized extraction was used. The influence of temperature on different residence times was evaluated, and to verify the effect of the catalyst on the process, non-catalytic reactions were conducted. In reactions without the use of catalyst, a temperature of 250 °C was required to obtain >90 % esters yield. In the catalytic reactions, the operating conditions were reduced to 225 °C, to obtain ∼96 % esters yield, also providing the synthesis of a greater quantity of GLC, and a glycerol-free sample. The wet modification of powdered glass waste with KF results in the K2SiF6, NaF, CaF2, and KCaF3 phases. The laser-induced breakdown spectroscopy analyses showed the presence of fluorinated compounds in the catalyst. Furthermore, calcium and sodium ions from the glass waste matrix support were the source for the crystalization of K2SiF6/CaF2/KCaF3 and NaF phases, respectively. The catalyst showed a good catalytic activity, promoting high ester and GLC formation at 225 °C, 10 min and 10 MPa, remaining with good performance even after 8h of reaction, but it is important to mention that the stability of the catalyst needs to be improved due to the leaching of K to Ca.

A Study of Hydroxyl-Terminated Block Copolyether-Based Binder Curing Kinetics.

In order to determine the curing reaction model and corresponding parameters of hydroxyl-terminated block copolyether (HTPE) and provide a theoretical reference for its practical application, the non-isothermal differential scanning calorimetry (DSC) method was used to analyze the curing processes of three curing systems with HTPE and N-100 (an aliphatic polyisocyanate curing agent), isophorone diisocyanate (IPDI), and a mixture of N-100 and IPDI as curing agents. The results show that the curing activation energy of N-100 and HTPE was about 69.37 kJ/mol, slightly lower than the curing activation energy of IPDI and HTPE (75.60 kJ/mol), and the curing activation energy of the mixed curing agent and HTPE was 69.79 kJ/mol. The curing process of HTPE conformed to the autocatalytic reaction model. The non-catalytic reaction order (n) of N-100 and HTPE was about 1.2, and the autocatalytic order (m) was about 0.3, both lower than those of IPDI and HTPE. The reaction kinetics parameters of the N-100 and IPDI mixed curing agent with HTPE were close to those of N-100 and HTPE. The verification results indicate a high degree of overlap between the experimental data and the calculated data.

Recovery of methyl methacrylate from waste poly (methyl methacrylate) pellets using a low-temperature plasma and zeolites

A dielectric barrier discharge (DBD) plasma method with zeolite catalysts was applied to waste poly (methyl methacrylate) (PMMA) pellets to retrieve methyl methacrylate (MMA), methacrylic acid, and methanol at a relatively low temperature. Waste PMMA pellets were provided in the form of post-industrial recycled (PIR) PMMA. Three types of zeolite catalysts such as HY, H-zeolite socony mobil-5 (HZSM-5), and H-mobil composition of matter-22 (HMCM-22) were tested to assess their catalytic performance for retrieval under plasma irradiation. By conducting comparative examples such as non-catalytic, catalytic, and plasma-assisted non-catalytic thermolysis reactions, the cooperative effects of the DBD plasma discharge and zeolite catalyst were investigated. HMCM-22 was found to be more effective, especially for the retrieval of MMA. In the cases of non-catalytic and catalytic thermolysis at 300 °C, conversions of PMMA were found 50.9 % and 52.6 %, respectively. By contrast, plasma-assisted non-catalytic thermolysis showed that the PMMA conversion improved by up to 90.6 %, whereas the yield of MMA was relatively low (34.6 %). Using zeolite catalysts in the plasma bed also improved PMMA conversion by up to nearly 90 %. The liquid products yields were comparable for HY and HZSM-5. By contrast, HMCM-22 afforded the highest liquid product yield. Notably, the HMCM-22 case showed highest MMA yield at nearly 53.1 %, which seems highly related to a large amount of Brønsted acid sites. More importantly, the byproducts having odor issue such as methyl pyruvate and 2,3-butanedione were not produced in such a plasma-assisted catalytic or non-catalytic conversion method.

Quantification of cooking oil fumes using non-catalytic transesterification: A reliable method for indoor air quality assessment

Cooking oil fumes (COFs), which are aerosols formed via the interaction of water and oil (triglycerides, TGs), contribute to the incidence of lung cancer. Control of indoor COF concentrations has not yet been established, as reliable methods for quantifying COFs have not been developed. This study aimed to quantify COFs based on the derivatization of TGs via a non-catalytic transesterification reaction. Our investigation into the thermolytic behaviors of oil confirmed that COFs generated at ≤ 200 °C primarily consisted of oil and water vapor. Alkali-catalyzed transesterification is commonly used for the derivatization of TGs. However, it is sensitive to impurities such as free fatty acids and water, leading to side reactions. Furthermore, this reaction requires additional purification steps to separate the catalyst and has long reaction times (≥120 min). In contrast, non-catalytic transesterification is not sensitive to impurities and can achieve a conversion yield of over 97 wt% within 1 min. The conversion yield of non-catalytic transesterification was higher than that of the alkali-catalyzed method, indicating that non-catalytic transesterification could be a more reliable method for quantifying COFs. Additionally, the concentration of COFs determined using non-catalytic derivatization was higher than that obtained using the conventional aerosol analysis method (PM gravimetric method). This approach addresses a critical gap in current practices, offering a valuable tool for assessing and regulating COF levels in indoor spaces. Consequently, this contributes to broader efforts aimed at mitigating potential adverse health effects associated with exposure to COFs.

Structural Diversification of Pyrazinone Metabolites via Spontaneous Oxa-Michael Addition in Staphylococcus xylosus.

A family of pyrazinone metabolites (1-11) were characterized from Staphylococcus xylosus ATCC 29971. Six of them were hydroxylated or methoxylated, which were proposed to be produced by the rare noncatalytic oxa-Michael addition reaction with a water or methanol molecule. It was confirmed that isopropyl alcohol can also be the Michael donor of the reaction. 1-7 and the synthetic precursor 2a showed significant inhibition of breast cancer cell migration.

Multi-dimensional CFD-Mask R-CNN and CFD-watershed segmentation approach for multiphase non-catalytic gas-solid reactions: A case study for hydrogen reduction of porous iron oxide pellets

The direct reduction of iron oxide (DRI) using hydrogen is a promising method for clean steelmaking. Previous studies used one-dimensional models to explore this non-catalytic gas–solid reaction, but they lacked accuracy in assessing the impact of pellet shape. To tackle this issue, a multi-dimensional computational fluid dynamic (CFD) method has been employed, integrating a novel porous three-interface unreacted shrinking core model (USCM) to explore the effects of pellet shape through multiphase reactions of Fe2O3 → Fe3O4 → FeO → Fe by pure hydrogen. The model incorporates Knudsen, molecular, and effective diffusion mechanisms, alongside a continuous porosity function. Validation against previous experiments within a temperature range of 800–1000 °C and varying porosity is performed by solving four partial differential equations (PDEs) of mass and momentum balance in a porous media using the finite element method (FEM). Subsequently, a dataset comprising 754 images of pellets from the industrial DRI unit is collected and applied for the mask region-based convolutional neural network (Mask R-CNN) algorithm coupled with CFD, to draw geometries and simulate DRI to study indentations and protrusions of pellets. Furthermore, watershed segmentation is applied to investigate the shapes and real sizes of pellets from their images. The Mask R-CNN achieves intersection over union (IoU), precision, and recall percentages of 86.1 %, 87.3 %, and 87.2 % on average, respectively. Pellet shape investigations reveal notable discrepancies in wustite phase profiles and porosity. A nuanced impact is discerned regarding the DRI in 2D shape deviation, while 3D model errors in solid conversion time range from 3 % to 12.8 %.

Hydrogen peroxide assisted oxidative liquefaction of alkaline lignin over cobalt-nickel loaded zirconia catalysts

Research toward the oxidative fractionation of lignin is gaining attention due to the selective breaking of a sub-aromatic unit of lignin's complex structure into monomeric phenolic. This study aims to investigate the liquefaction tendency of alkaline lignin by screening the synergistic effect of Co and Ni loaded on synthesized (syn) ZrO2 catalyst under the applied mild oxidative reaction conditions of molecular oxygen and hydrogen peroxide. Compared to the non-catalytic reaction (38.1 wt%), a significant improvement in the bio-oil yield (53.7 wt%) was obtained with the 5Co–5Ni/ZrO2-syn catalyst under the oxidative condition of molecular oxygen. However, only 44.3 wt% bio-oil was observed with commercial (com) 5Co–5Ni/ZrO2-com catalyst. The synergistic study of Co and Ni metal exhibited a diverse impact on the fractionation of lignin into respective product yields (bio-oil, gas, and char). Notably, adding a catalytic amount of hydrogen peroxide showed a remarkable improvement in liquefaction. The maximum bio-oil yield (72.1 wt%), and a maximum conversion (77.9%) were noticed with 0.5 mL H2O2 at 120 °C/30 min under the atmospheric molecular oxygen. The GC-MS analysis of bio-oil (5Co–5Ni/ZrO2-syn-HP) attributed to a high quantity of guaiacyl phenolic with a maximum proportion of benzaldehyde-3-hydroxy-4-methoxy (65.3%). The 5Co–5Ni/ZrO2-syn catalyst was also examined for the three catalytic cycles, which did not show any significant loss in product yield.

Quantum chemical pathways for the formation of 2,3,7,8-tetrachloro dibenzo-p-dioxin (TCDD) from 2,4,5-trichlorophenol: a mechanistic and thermo-kinetic study.

Dioxins, specifically 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD), are highly toxic dioxins known for their severe health impacts and persistent environmental pollutants. This study focuses on understanding the formation pathways of TCDD from its precursor molecule 2,4,5-trichlorophenol (2,4,5-TCP). In our exploration of reaction pathways from 2,4,5-trichlorophenol (TCP), we delve into three reaction mechanisms: free-radical, direct condensation, and anionic. Our findings highlight the significance of the radical mechanism, particularly propagated by H radicals, with a notable increase in dioxin formation around 900K. These results are consistent with experimental observations indicating an increase in the conversion of trichlorophenol from 600 to 900K in the non-catalytic gas phase reaction. Thermodynamic parameters (∆H, ∆S, and ∆G), reaction barriers, and rate constants (k) were calculated across a temperature range of 300-1200K to support the findings and provide insights into the optimal temperature range for controlling dioxins during the incineration process. In this study, quantum chemical calculations were conducted using density functional theory (DFT) with the B3LYP functional and the 6-311 + + G(d,p) basis set in Gaussian 16 software. Stationary points, including transition states (TS), were confirmed with frequency calculations. Intrinsic reaction coordinate (IRC) calculations ensured minimum energy paths between TS and products, visualized in GaussView 6.0 Program. Single-point energy calculations utilized a more precise basis set, 6-311 + + G(3df,2p), for enhanced energy accuracy, incorporating zero-point vibrational energy (ZPE) and other energy corrections. These calculations were repeated over a temperature range of 298.15-1200K at 1atm pressure. Finally, rate constant (k) expressions associated with TCDD formation were determined using transition state theory (TST).

A facile approach for design of novel semiconducting thiazolo[5,4-d]thiazole-based conjugated polymers in ambient conditions

The design of conjugated polymers with advanced properties is a significant task for the development of organic electronics. At the same time, it is important to pay attention to the methods of their synthesis, excluding toxic and expensive reagents, following the trends in sustainability. In this study, six thiazolothiazole-based conjugated polymers with thiophene, fluorene, phenylene, and benzodithiophene moieties were synthesized and thoroughly characterized. All materials were obtained through a non-catalyzed condensation reaction of carbonyl derivatives with rubeanic acid under ambient conditions. It is shown that the optoelectronic and electrophysical properties of polymers are suitable for their application in organic or hybrid electronic devices. The certain polymers are found to be promising hole-transport interlayer materials in perovskite solar cells, thus featuring the great potential of proposed methods of development of organic semiconductors.

Multiscale modeling of non-catalytic gas-solid reactions applied to the hydrogen direct reduction of iron ore in moving-bed reactor

Direct hydrogen reduction (H-DR) is a promising technology for green ironmaking. Given the absence of commercial H-DR data, computational simulation is a powerful tool for engineering and overcoming the complexity of the system. This study develops a multiscale moving-bed reactor model to simulate non-catalytic gas-solid reactions and evaluate parameters at the pellet scale that hierarchically impact the performance at reactor scale. The reactor and solid particles are treated as coupled physical domains, enabling the computation of the solid transformations along both scales. Predictions for H-DR process highlight the substantial supply of H2 molar flow in enhancing reactor performance. A sensitivity multivariate analysis revealed the significant effect of pellet structural characteristics and gas inlet conditions on the process. Increased pellet porosity offers flexibility for process optimization, enabling the use of lower H2 percentages and temperatures. These findings provide valuable insights into optimizing H-DR process, improving energy efficiency, and better H2 utilization.

Selective production of phenolic monomer via catalytic depolymerization of lignin over cobalt-nickel-zirconium dioxide catalyst

The utilization of lignin, an abundant and renewable bio-aromatic source, is of significant importance. In this study, lignin oxidation was examined at different temperatures with zirconium oxide (ZrO2)-supported nickel (Ni), cobalt (Co) and bimetallic Ni-Co metal catalysts under different solvents and oxygen pressure. Non-catalytic oxidation reaction produced maximum bio-oil (35.3 wt%), while catalytic oxidation significantly increased the bio-oil yield. The bimetallic catalyst Ni-Co/ZrO2 produced the highest bio-oil yield (67.4 wt%) compared to the monometallic catalyst Ni/ZrO2 (59.3 wt%) and Co/ZrO2 (54.0 wt%). The selectively higher percentage of vanillin, 2-methoxy phenol, acetovanillone, acetosyringone and vanillic acid compounds are found in the catalytic bio-oil. Moreover, it has been observed that the bimetallic Co-Ni/ZrO2 produced a higher amount of vanillin (43.7% and 13.30 wt%) compound. These results demonstrate that the bimetallic Ni-Co/ZrO2 catalyst promotes the selective cleavage of the ether β-O-4 bond in lignin, leading to a higher yield of phenolic monomer compounds.

Copper and zinc-impregnated mesoporous gamma-alumina catalyst for hydrothermal liquefaction of alkali lignin

The complete utilization of lignocellulose is a sustainable key for bio-refineries, where the utilization of evitable lignin is a great challenge owing to its structural complexity. Here, the effect of Cu and Zn-loaded mesoporous γ-Al2O3 catalysts was examined for the first time for the hydrothermal liquefaction of alkali lignin in an ethanol/water solvent system. It showed excellent performance towards the liquefaction as compared to that of (commercial) com-5Cu/γ-Al2O3 catalyst. Here, the bio-oil yield was observed to be 47.7 wt% for com-5Cu/Al catalyst which was increased to 59.1% for syn-5Cu/Al. It was increased substantially to 65.4 wt% for syn-10Cu/Al. However, only a 40 wt% bio-oil yield was found for the non-catalytic (NC) reaction. Additionally, a further significant improvement to 74.7 wt% was noticed for Zn (5 wt%) modified syn-10Cu/Al catalyst. Here, the screening of the water-ethanol mixture, and reaction parameters were also evaluated which showed a small increase in bio-oil yield to 77.4 wt% for ethanol/water (75/25, v/v). The GC-MS analysis of bio-oil exhibited the high specificity of vanillin (69.3%) for syn-10Cu-5Zn/Al. The 1H NMR and FT-IR investigation also validate the diverse functionality of bio-oils. The reusability of the optimum catalyst (syn-10Cu-5Zn/Al) was also tested for three successive catalytic cycles that exhibited the good performance of the catalyst up to the second cycle.

Advancements and Perspectives toward Lignin Valorization via O-Demethylation.

Lignin represents the largest aromatic carbon resource in plants, holding significant promise as a renewable feedstock for bioaromatics and other cyclic hydrocarbons in the context of the circular bioeconomy. However, the methoxy groups of aryl methyl ethers, abundantly found in technical lignins and lignin-derived chemicals, limit their pertinent chemical reactivity and broader applicability. Unlocking the phenolic hydroxyl functionality through O-demethylation (ODM) has emerged as a valuable approach to mitigate this need and enables further applications. In this review, we provide a comprehensive summary of the progress in the valorization of technical lignin and lignin-derived chemicals via ODM, both catalytic and non-catalytic reactions. Furthermore, a detailed analysis of the properties and potential applications of the O-demethylated products is presented, accompanied by a systematic overview of available ODM reactions. This review primarily focuses on enhancing the phenolic hydroxyl content in lignin-derived species through ODM, showcasing its potential in the catalytic funneling of lignin and value-added applications. A comprehensive synopsis and future outlook are included in the concluding section of this review.

Actively Learned Optimal Sustainable Operation of Plasma-Catalyzed Methane Bireforming on La0.7Ce0.3NiO3 Perovskite Catalyst

Actively Learned Optimal Sustainable Operation of Plasma-Catalyzed Methane Bireforming on La_0.7Ce_0.3NiO₃ Perovskite Catalyst

Trans-Cyclooctenes as Scavengers of Bromine Involved in Catalytic Bromination.

Scavengers that capture reactive chemical substances are used to prevent the decomposition of materials. However, in the field of catalysis, the development of scavengers that inhibit background pathways has attracted little attention, although the concept will open up an otherwise inaccessible reaction space. In catalytic bromination, fast non-catalyzed background reactions disturb the catalytic control of the selectivity, even when using N-bromoamide reagents, which have a milder reactivity than bromine (Br2 ). Here, we developed a trans-cyclooctene (TCO) bearing a 2-pyridylethyl group to efficiently retard background reactions by capturing Br2 in bromocyclization using N-bromosuccinimide. The use of less than a stoichiometric amount of the TCO was sufficient to inhibit non-catalyzed reactions, and mechanistic studies using the TCO revealed that in situ-generated Br2 provides non-catalyzed reaction pathways based on a chain mechanism. The TCO is useful as an additive for improving enantioselectivity and regioselectivity in catalytic reactions. Cooperative systems using the TCO with selective catalysts offer an alternative strategy for optimizing catalyst-controlled selectivity during bromination. Moreover, it also served as an indicator of Br2 involved in catalytic reaction pathways; thus, the TCO was useful as a probe for mechanistic investigations into the involvement of Br2 in bromination reactions of interest.