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An electrophotochemical ring-opening bromination of unstrained tert-cycloalkanols has been developed. This electrophotochemical method enables the oxidative transformation of cycloalkanols with 5- to 7-membered rings into synthetically useful ω-bromoketones without the use of chemical oxidants or transition-metal catalysts. Alkoxy radical species would be key intermediates in the present transformation, which generate through homolysis of the O-Br bond in hypobromite intermediates under visible light irradiation.

We report the first X-ray single crystal structures of hypochlorite (ClO- ) and hypobromite (BrO- ) salts, including hydrated sodium hypochlorite, a staple of the chlorine industry and ubiquitous bleaching and disinfection agent for almost 200 years. The structures, supported by variable-temperature Raman spectroscopy on individual crystals and periodic density-functional theory (DFT) calculations, provide insight into solid-state geometry and supramolecular chemistry of hypohalite ions.

The freezing-induced acceleration of bromate reduction by humic substances (HS) contributes to HS bromination and the formation of organobromine compounds (OBCs). Herein, we report the enhanced reduction of bromate by dissolved organic matter and the formation of large amounts of OBCs in freezing solutions. After 48 h of freezing process, 78.1-100% of bromate was reduced by DOM at different initial concentrations of bromate and DOM in acidic solutions (pH 3 and 4). Bromide was one of the main reduction products, and it accounted for 30.9-47.8% of the total bromine content. Except for bromide, a large amount of OBCs formed by brominating DOM with reactive bromine species, like hypobromite, were detected. The conversion of bromate to OBCs, calculated as the total organobromine content to the initial bromate content, ranged from 28.2 to 52.5% and was mainly dependent on the bromate/DOM content. About 110-603 species of OBCs were detected by Fourier transform ion cyclotron resonance mass spectrometry, and they were primarily highly unsaturated and phenolic compounds. By analyzing the spectral variation before and after the freezing process, we found the disappearance of 900 compounds containing only C, H, and O with a low carbon oxidation state that was regarded as the main reductant of bromate. Our findings call for further investigation of the processes and the effects of bromate formation in aqueous environments.

2-Bromomethyl-2,3-dihydrobenzofurans are valuable and highly functionalized compounds that can be obtained by an intramolecular reaction between 2-allylphenols and a bromenium ion source (Br+). Due to the ineffectiveness of the safe and easy-to-handle brominating agent N-bromosuccinimide (NBS) to deliver the desired products, a catalytic process using a mixture of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and acetic acid was conceived. We hypothesized that this catalytic system delivers in situ acetyl hypobromite (AcOBr) as the active brominating agent, enabling the conversion of a range of 2-allylphenols with diverse electron densities to the products. The protocol was robust enough to permit the reaction to be scaled up to 10 mmols of starting material. Besides, the functional group interconversion with a 2-bromomethyl-2,3-dihydrobenzofuran derivative was successfully demonstrated.

Using 15N stable isotope as a tracer to quantify N transformation rates in isotope-enrichment experiments improves understanding of the N cycle in various ecosystems. However, measuring 15N-nitrate (15NO3−) in small volumes of water for these experiments is a major challenge due to the inconvenience of preparing samples by traditional techniques. We developed a “REOX/MIMS” method by applying membrane inlet mass spectrometry (MIMS) to determining 15NO3− concentrations in a small volumes of water from isotope-enrichment experiments after converting the dissolved inorganic N to N2. The nitrates (NO3− + NO2−) were reduced to NH4+ with zinc powder, and the ammonium (NH4+) was then oxidized to N2 by hypobromite iodine solution. The resulting 29N2 and 30N2 were measured via MIMS. This optimized protocol provides a sensitive (~0.1 μM) and precise (relative standard deviation = 0.1–4.37%) approach to quantify 15NO3− concentrations (0.1–500 µM) in water samples over a wide range of salinities (0–35‰) and in 2 M KCl solution with excellent calibration curves (R2 ≥ 0.9996, p

We report the first single crystal structures of hypochlorite and hypobromite salts, including hydrated sodium hypochlorite - a ubiquitous bleaching and disinfection agent in use for almost 200 years. The structures represent the first characterization of fundamentally important hypochlorite and hypobromite anions in the solid state, by X-ray crystallography and are supported by Raman spectroscopy on individual crystals. The structural analysis provides insight into supramolecular chemistry of the hypohalite ions in the hydrated environment of the NaOCl.5H2O and NaOBr.5H2O solid salts, and reveals measured Cl-O and Br-O bond lengths of 1.69 A and 1.82 A, respectively, which are significantly longer than those for corresponding higher-valence oxoanions, and in agreement with the values spectroscopically determined for hypohalous acids and corresponding oxides in the gas phase.

The determination of fixed ammonium (NH₄⁺) normally involves hydrofluoric acid (HF) digestion to decompose clay minerals following a rigorous pretreatment to control interference by organic nitrogen (N); however, the methods are tedious and time-consuming, and recoveries can be incomplete if the soil under analysis was recently fertilized with ammoniacal N. Diffusion methods were developed to simplify and improve this determination, which utilize a potassium chloride (KCl) pretreatment to clearly differentiate exchangeable from nonexchangeable NH₄⁺. In these methods, the HF digest is treated with magnesium carbonate (MgCO₃) to neutralize residual acidity and precipitate magnesium fluoride (MgF₂), and fixed NH₄⁺-N is then liberated with magnesium oxide (MgO) as diffusion is performed on an orbital shaker for 3 h at 45 to 50°C (Method A) or for 3 d at 20 to 25°C (Method B). When averaged across 16 diverse soils, both diffusion methods were in close agreement with the Silva-Bremner technique using a potassium hypobromite (KOBr) pretreatment, although significant discrepancies were more common for Method A than B, indicating greater potential for organic interferences. In a study to compare recoveries of recently fixed ¹⁵NH₄⁺-N, Method A was significantly higher than the procedure of Silva and Bremner. The latter finding leaves no doubt about the need to avoid the use of KOBr for measuring fixed NH₄⁺ in soils recently fertilized with ammoniacal N, and demonstrates that the methods described will be advantageous for tracer research involving ¹⁵N.

An electrochemical methodology for the Minisci-type trifluoromethylation of electron-deficient heterocycles mediated by cheap and easily available bromide ions has been developed. By virtue of the in situ generated sulfonyl hypobromite intermediate, the CF3 radical can be regulated and controlled at a low concentration, thereby improving the reaction efficiency over direct electrolysis. Also, this indirect electrochemical process is performed in a beaker-type undivided cell under galvanostatic conditions, without using external expensive supporting electrolytes. This protocol provides an alternative electrochemical trifluoromethylation methodology for the late-stage functionalization of biologically important molecules.

The rapidly increasing use of graphene oxide (GO) necessitates the immediate investigation of the environmental fate and effects of this unique material. To date, little is known about the transformation of GO in environmental media, especially in water and wastewater treatment systems. This study explored the changes in the physicochemical properties of GO that result from (photo)bromination by simulating the reactions experienced by GO during water and wastewater treatment. The surface oxygen functionalities of GO considerably changed upon treatment. Specifically, the C OH and COOH groups of GO were lost under bromination, and the reduction of GO was enhanced under photobromination. GO sheets wrinkled and fragmented under bromination, and GO decomposition was enhanced by photobromination. The decreases in O/C ratio and GO decomposition in the presence of bromine were mainly attributed to the relatively high oxidation potential of bromine, which can oxidize carbon nanosheets. The oxidation of carbon nanosheets, in turn, resulted in the decomposition and formation of brominated disinfection by-products. Irradiation, hypobromous acid/hypobromite (HOBr/OBr−), and reactive radicals, such as OH, Br , BrO and Br2 −, may all affect the physicochemical transformation of GO in the presence of bromine and simulated solar light. Bromination and photobromination drastically changed the aggregation and sedimentation behavior of GO. The findings of this study advance knowledge on the transformations of GO in water treatment systems and provide insight on the environmental fate of the transformation products of GO.

The initial energy in a reactive intermediate is derived from the transition state before the intermediate but can affect selectivity after the intermediate. In this way an observable selectivity can report on a prior, kinetically hidden mechanistic step. This new type of mechanistic probe is demonstrated here for the oxidation of 1-methylcyclobutanol by phthaloyl peroxide/Bu(4)N(+)Br(−), and it supports a hypobromite chain mechanism in place of the previously proposed hydrogen atom transfer mechanism.

Iodosobenzene (PhIO) is known to be a potent oxidant for alcohols in the presence of catalytic bromide in water. In order to understand this important and practical oxidation process, we have conducted density functional theory studies to shed light on the reaction mechanism. The key finding of this study is that PhIO is not the reactive oxidant itself. Instead, the active oxidant is hypobromite (BrO-), which is generated by the reaction of PhIO with bromide through an SN2-type reaction. Critically, water acts as a cocatalyst in the generation of BrO- through lowering the activation energy of this process. This investigation also demonstrates why BrO- is a more powerful oxidant than PhIO in the oxidation of alcohols. Other halide additives have been reported experimentally to be less effective catalysts than bromide - our calculations provide a clear rationale for these observations. We also examined the effect of replacing water with methanol on the ease of the SN2 reaction, finding that the replacement resulted in a higher activation barrier for the generation of BrO-. Overall, this work demonstrates that the hypervalent iodine(III) reagent PhIO can act as a convenient and controlled precursor of the oxidant hypobromite if the right conditions are present.

RATIONALE There has never been a highly sensitive method for simultaneously measuring the δ15 N and δ18 O values of nitrate ions (NO3- ) and the δ15 N values of ammonium ions (NH4+ ) in particulate matter using denitrifying bacteria. In this study, we explored a method that combines use of an anion-exchange resin and denitrifying bacteria to make such measurements. METHODS The δ15 N-NH4+ values of samples obtained using the hypobromite and denitrifying bacteria method were measured by isotope ratio mass spectrometry. Tests (effect of flow rate, breakthrough, and acid concentration) were conducted to verify the removal of NO3- using an AG1-X8 anion-exchange resin for NH4+ measurements and the enrichment of NO3- . For aerosol samples, the optimized method was used to measure the δ15 N-NO3- , δ18 O-NO3- , and δ15 N-NH4+ values of atmospheric particulate matter (PM2.5 , aerodynamic diameter

The nucleophilicities of the oxidants hydroperoxide, hypochlorite, hypobromite, bromite, and peroxymonosulfate were determined by following the kinetics of their reactions with a series of benzhydrylium ions of known electrophilicity (E) in alkaline, aqueous solutions at 20 °C. The reactivities of the oxidants correlate only weakly with their basicities. Analyzing the rate constants by using the relationship log k2 = sN(N + E) gave the parameters N (and sN), which were applied to predict the rates of Weitz–Scheffer epoxidations.

Decomposition of aqueous suspensions of uranium(IV) oxalate under the action of an ozone–oxygen mixture was studied. The process occurs in two steps. In the first step, the U(IV) oxidation with the formation of oxalic acid uranyl solutions prevails. The second step involves decomposition of oxalate ions and hydrolysis of uranyl ions. An increase in temperature accelerates the transformation of uranium(IV) oxalate into uranium(VI) hydroxide compounds. In solutions containing KBr or UO2Br2, the following reaction occurs: O3 + Br– → O2 + BrO–. The arising hypobromite ions and hypobromous acid oxidize uranium(IV) oxalate extremely efficiently. The possible mechanism of ozonation of aqueous uranium(IV) oxalate suspensions is discussed.

It has been discovered for the first time that gaseous ozone in the presence of carbon dioxide and water vapor interacts with crystalline potassium bromide giving gaseous Br2 and solid salts KHCO3 and KBrO3. Molecular bromine and hydrocarbonate ion are the products of one and the same reaction described by the stoichiometric equation 2KBr(cr.) + O3(gas) + 2CO2(gas) + H2O(gas) → 2KHCO3(cr.) + Br2(gas) + O2(gas). The dependencies of Br2, KHCO3 and KBrO3 formation rates on the concentrations of O3 and CO2, humidity of initial gas mixture, and temperature have been investigated. A kinetic scheme has been proposed that explains the experimental regularities found in this work on the quantitative level. According to the scheme, the formation of molecular bromine and hydrocarbonate is due to the reaction between hypobromite BrO−, the primary product of bromide oxidation by ozone, with carbon dioxide and water; bromate results from consecutive oxidation of bromide ion by ozone Br − → + O 3 , − O 2 BrO − → + O 3 , − O 2 BrO 2 − → + O 3 , − O 2 BrO 3 − .

Systems based on organic complexes of tribromide anion generate upon dissolution in water nucleophile–oxidant couple HOBr/BrO– and accelerate hydrolysis of ethyl 4-nitrophenyl ethylphosphonate, diethyl 4-nitrophenyl phosphate, and 4-nitrophenyl p-toluenesulfonate by a factor of 15–90 in the presence of cationic surfactant micelles. As in water, hypobromite ion in surfactant micelles acts as α-nucleophile, and the magnitude of the α-effect almost does not change in going from water to micelles. Micellar effects of surfactants are determined by the nucleophilicity of hypobromite ion in surfactant micelles and by solubilization of the substrate and BrO–, which largely depend on the counterion concentration in the micelle surface layer. The main factor responsible for the observed acceleration is increased reactant concentration in the micellar pseudophase.

Herein we present the first example of aryl radical formation via the visible light-mediated decarboxylation of aryl carboxylic acids using photoredox catalysis., Herein we present the first example of aryl radical formation via the visible light-mediated decarboxylation of aryl carboxylic acids using photoredox catalysis. This method constitutes a mild protocol for the decarboxylation of cheap and abundant aryl carboxylic acids and tolerates both electron-rich substrates and those lacking ortho-substitution. The in situ formation of an acyl hypobromite is proposed to prevent unproductive hydrogen atom abstraction and trapping of the intermediate aroyloxy radical, enabling mild decarboxylation.

Ferrate (VI) is traditionally recognized as a safe oxidant without production of disinfection byproducts (DBPs). However, here we detected probable carcinogenic bromate (BrO3(-)) during ferrate(VI) oxidation of bromide (Br(-))-containing water, and evaluated the effects of pH, ferrate(VI) dose, initial Br(-) concentration, and co-existing anions on the BrO3(-) formation. BrO3(-) was produced at a moderately-weakly acidic pH condition and in the absence of phosphate that was commonly applied as a buffer and stabilizing agent in previous ferrate(VI) studies. At pH 5.0, the produced BrO3(-) was increased from 12.5 to 273.8 μg/L with the increasing initial Br(-) concentration from 200 to 1000 μg/L at 10 mg/L Fe(VI), corresponding to an increase in the molar conversion ([BrO3(-)]/initial [Br(-)]) from 2.3% to 10.3%, in a bicarbonate-buffered solution. As pH increased to 7.0, the BrO3(-) concentration gradually dropped. The BrO3(-) production appeared to be associated with the oxidation by high valence iron species (i.e. Fe(VI), Fe(V) and Fe(IV)). Two key intermediate products (i.e. hypobromous acid/hypobromite (HOBr/OBr(-)) and hydrogen peroxide (H2O2)) relevant to the bromate formation were identified. The production of HOBr, a requisite intermediate for the ensuing bromate formation, was indirectly validated through identification of bromine-containing trihalomethanes and haloacetic acids during ferrate oxidation in a natural water, though these bromo-organic DBPs produced were insignificant. Furthermore, the inhibition effects of various anions on the formation of BrO3(-) followed chloride sulfate silicate phosphate. More H2O2 was detected at higher phosphate concentration. It could reduce HOBr to Br(-), thereby inhibiting the bromate formation.

Antimicrobial photocatalysis involves the UVA excitation of titanium dioxide (TiO2) nanoparticles (particularly the anatase form) to produce reactive oxygen species (ROS) that kill microbial cells. For the first time we report that the addition of sodium bromide to photoactivated TiO2 (P25) potentiates the killing of Gram-positive, Gram-negative bacteria and fungi by up to three logs. The potentiation increased with increasing bromide concentration in the range of 0–10 mM. The mechanism of potentiation is probably due to generation of both short and long-lived oxidized bromine species including hypobromite as shown by the following observations. There is some antimicrobial activity remaining in solution after switching off the light, that lasts for 30 min but not 2 hours, and oxidizes 3,3′,5,5′-tetramethylbenzidine. N-acetyl tyrosine ethyl ester was brominated in a light dose-dependent manner, however no bromine or tribromide ion could be detected by spectrophotometry or LC-MS. The mechanism appears to have elements in common with the antimicrobial system (myeloperoxidase + hydrogen peroxide + bromide).

N-Bromophthalimide (NBP)-triggered bromination of aromatic compounds has been studied in the presence of aqueous acetic acid. Reaction Kinetics indicated first order in [NBP] and zero order in [Anisole]. The reactions afforded very good yields of corresponding bromo derivatives under kinetic conditions. The mechanism of the reaction is explained through the formation of acetyl hypobromite due to the interaction of NBP and acetic acid, which in turn reacts with anisole to afford a bromo derivative of anisole.

Sulfate radical-based advanced oxidation processes (SR-AOPs) show a good prospect for effective elimination of organic contaminants in water due to the powerful oxidation capability and good adaptability of sulfate radical (SO4•-). However, great concerns have been raised on occurrence of the carcinogenic byproduct bromate (BrO3-) in SR-AOPs. The present article aims to provide a critical review on BrO3- formation during bromine (Br)-containing water oxidation by various SR-AOPs. Potential reaction mechanisms are elaborated, mainly involving the sequential oxidation of bromide (Br-) by SO4•- to Br-containing radicals (e.g., bromine atom (Br•)) and then to hypobromous acid/hypobromite (HOBr/OBr-), which acts as the requisite intermediate for BrO3- formation. Some key influencing factors on BrO3- formation are discussed. Particularly, dissolved organic matter (DOM) as a component ubiquitously present in aquatic environments shows a significant suppression effect on BrO3- formation, primarily attributed to the reduction of Br• by DOM to Br-. The reaction of Br• with DOM can hardly produce organic brominated byproducts, while their formation is mainly due to the bromination of HOBr/OBr- generated through nonradical pathways such as the direct reaction of Br- with oxidants (e.g., peroxymonosulfate (PMS)) or other reactive species derived from catalytic activators (e.g., Co(III) in the Co(II)/PMS process). The debromination of brominated pollutants during their oxidation by SO4•- results in the release of Br-, which, however, is not further transformed to BrO3- until coexisting organic matters are mineralized nearly completely. Furthermore, possible strategies for control of BrO3- formation in SR-AOPs as well as the future research needs are proposed.

Controlling membrane fouling and disinfection by-products (DBPs) is an ongoing challenge in achieving sustainable membrane-based seawater desalination. This study assessed the efficacy of a new disinfectant, stabilized hypobromite, for controlling biofouling and DBP formation during reverse osmosis (RO) membrane treatment of seawater. Accelerated chemical exposure tests revealed that stabilized hypobromite did not degrade a commercial polyamide RO membrane; thus, unlike other powerful oxidants, it is able to remain as a residual chemical on membrane surfaces. In our experiments, stabilized hypobromite also effectively inactivated bacteria in seawater and reduced potential organic foulants (e.g., humic acid-like and protein-like substances). Disinfection at a stabilized hypobromite dose of 5 mg-Cl2/L resulted in the formation of trihalomethanes (THMs), haloacetic acids (HAAs), and bromate at 55, 29, and, Desalination, 488, art.no.114507; 2020

Hypobromous acid and molecular bromine have been described as the active species involved in the oxidative bromination using perhydrolase, which catalyzes the reaction from acetic acid and hydrogen peroxide to peracetic acid (AcOOH). However, the brominating activity of them in a chemical model system was lower than that of the active species produced by the spontaneous reaction between AcOOH and Br−. Consequently, acetyl hypobromite (AcOBr) was suggested as new active species on the bromination by detection of the decarboxylation in the reaction between AcOOH and Br− and the strong brominating power with some tolerance against H2O2. Its production mechanism was explained as the ionic reaction involving the protonated intermediate of AcOOH by kinetic analysis. Copyright © 2015 John Wiley & Sons, Ltd.

A simple and general method for the synthesis of highly substituted α-tropolone ethers that allows rapid access to the bis(tropolone) core of the antiproliferative metabolites (-)-gukulenins A and F (3, 4) is described. The reaction proceeds by thermolytic opening of gem-dibromobicyclo[4.1.0]heptane intermediates, which are readily accessed from simple starting materials. Mechanistic studies suggest the reaction proceeds via an autocatalytic process mediated by methyl hypobromite. This synthetic sequence allows access to a broad array of highly substituted α-tropolones.

An efficient continuous-flow procedure for the synthesis of tribromomethylsulfones and tribromomethanesulfonates has been developed starting from the corresponding methylsulfones or methanesulfonates and potassium hypobromite using a biphasic reaction. Two different continuous-flow systems were used and compared for the bromination reaction. Different derivatives were synthesized in excellent isolated yields in very short reaction times using a small excess of potassium hypobromite. Hypobromite can be synthesized continuously leading to the continuous production of the brominated derivates. With the optimized flow conditions, a throughput of up to 53 g/day was obtained. The bromination reaction in flow has significant advantages compared to the corresponding batch process.

Bromide-assisted electrochemical decarboxylation efficiently produces valuable nitriles in high yields from a wide range of naturally occurring amino acids in a single step. Bromide salts are used as both redox mediators and supporting electrolytes in a simple one-compartment setup. As demonstrated for lysine, the selectivity of the decarboxylation can be tuned towards nitriles, amines or amides.

Nitrogen (N) pollution in aquatic ecosystems has attracted much attention over the past decades, but the dynamics of this bioreactive element are difficult to measure in aquatic oxygen-transition environments. Nitrogen-transformation experiments often require measurement of 15N-ammonium (15NH4+) ratios in small-volume 15N-enriched samples. Published methods to determine N isotope ratios of dissolved ammonium require large samples and/or costly equipment and effort. We present a novel (“OX/MIMS”) method to determine N isotope ratios for 15NH4+ in experimental waters previously enriched with 15N compounds. Dissolved reduced 15N (dominated by 15NH4+) is oxidized with hypobromite iodine to nitrogen gas (29N2 and/or 30N2) and analyzed by membrane inlet mass spectrometry (MIMS) to quantify 15NH4+ concentrations. The N isotope ratios, obtained by comparing the 15NH4+ to total ammonium (via autoanalyzer) concentrations, are compared to the ratios of prepared standards. The OX/MIMS method requires only small sampl...

No report has been published concerning reference materials of ammonium chloride in which ammonium ions were accurately determined, though ammonium chloride is widely used as a standard of ammonium ions. In the present paper, accuracy of the coulometric titration of ammonium ions with electrogenerated hypobromite was studied. The authors found that the pH of electrolyte solution significantly affected the accuracy of the assay of ammonium ions. Lower assays were obtained at pH more than 8.5 or less than 8.0: much higher pH values led to evaporation of ammonia and much lower pH ones led to insufficient hypobromite generation or insufficient conditional equilibrium constant of the reaction between ammonium ions and hypobromite. Ammonium ions in ammonium chloride were certified by coulometric titration under an appropriate condition, and chloride ions in it were also certified by gravimetric titration based on standard sodium chloride. The first certified reference material with ammonium assay was developed which enabled more accurate ammonium determination than that before.

We report a new chemical method to determine the (15)N natural abundance (δ(15)N) for ammonium (NH4(+)) in freshwater (e.g., precipitation) and soil KCl extract. This method is based on the isotopic analysis of nitrous oxide (N2O). Ammonium is initially oxidized to nitrite (NO2(-)) by hypobromite (BrO(-)) using previously established procedures. NO2(-) is then quantitatively converted into N2O by hydroxylamine (NH2OH) under strongly acid conditions. The produced N2O is analyzed by a commercially available purge and cryogenic trap system coupled to an isotope ratio mass spectrometer (PT-IRMS). On the basis of a typical analysis size of 4 mL, the standard deviation of δ(15)N measurements is less than 0.3‰ and often better than 0.1‰ (3 to 5 replicates). Compared to previous methods, the technique here has several advantages and the potential to be used as a routine method for (15)N/(14)N analysis of NH4(+): (1) substantially simplified preparation procedures and reduced preparation time particularly compared to the methods in which diffusion or distillation is involved since all reactions occur in the same vial and separation of NH4(+) from solution is not required; (2) more suitability for low volume samples including those with low N concentration, having a blank size of 0.6 to 2 nmol; (3) elimination of the use of extremely toxic reagents (e.g., HN3) and/or the use of specialized denitrifying bacterial cultures which may be impractical for many laboratories.

This paper mainly compares the determination of ammonia in indoor air by hypobromite oxidation method and salicylic acid spectrophotometry, and selects higher precision, higher sensitivity, larger linear range and more stable results. The reproducible salicylic acid method is improved. In this way, the salicylic acid method is more convenient, time-saving and easy to operate, and is advantageous for the application of the method in a wider range.

Vinyl bromides bearing an arylamino group in the vicinal position are chemoselectively transformed into interesting α-arylamino-α′-bromoacetones through a straightforward oxidative hydrolysis promoted by calcium hypobromite under mild acidic conditions. Significantly, this particular combination [vinyl bromides and Ca(BrO)2] avoids bromination at both the aromatic ring and activated positions in groups substituting the amine nitrogen. The usefulness of this class of brominated ketones has been shown in a Wittig homologation.

In this study, we focused on the studying of taurine complexes with phenol and sodium hypochlorite, and of taurine with sodium hypobromite by spectrometry, reverse phase chromatography and ion-exchange chromatography. The formed complexes were studied under various conditions such as temperature (10, 20, 30, 40, 50 and 60 °C), and/or time of interaction (0, 5, 10, 15, 20, 25 and 30 min). In addition, we optimized high performance liquid chromatography coupled with UV detector for detection of taurine and its complexes with the acids. Taurine–phenol–hypochlorite complex was effectively separated under isocratic elution, mobile phase water:methanol 30:70 %, v:v, flow rate 1 mL min−1 and 55 °C. Taurine-bromamine complex was isolated under the following optimized conditions as isocratic elution, mobile phase water:methanol 85:15 % v:v, flow rate 1 mL min−1 and 55 °C. The limits of detection (3 S/N) were estimated as 1 μM for both types of complexes, i.e. for taurine. Further, we estimated recovery in one sample of urine (male 25 years), commercially achieved energy drink and tea leaves and varied from 79 to 86 %. Further, we aimed our attention at investigating the ability of the above characterized taurine and taurine complexes to scavenge reactive oxygen species. For this purpose, an ion-exchange liquid chromatography with post-column derivatization with ninhydrin and VIS detector was used. It clearly follows from the results obtained that taurine itself reacts with peroxide more intensely than in a bound form, which can be associated with the highest signal decrease. Complexes stabilized structure taurine against peroxide radicals, resulting in slower decreasing of peak heights. The most stable was taurine complexes with phenol and hypobromite.

A highly chemoselective oxidation of widely substituted aryl allylic sulfides, prepared by allylation of arylthioethers with KF-Celite, to the corresponding aryl allylic sulfoxide was achieved by employing calcium hypobromite. Neither over-oxidation to sulfones nor halogenation of the aromatic rings was observed. The protocol may be successfully applied for the oxidation of substituted allylic systems (i.e., 2-haloallyl) that per se could interact with the oxidizing agent.