Additional Bromine Research Articles

Simulating the spread of disinfection by-products and anthropogenic bromoform emissions from ballast water discharge in Southeast Asia

Abstract. Ballast water treatment is required for vessels to prevent the introduction of potentially invasive neobiota. Some treatment methods use chemical disinfectants which produce a variety of halogenated compounds as disinfection by-products (DBPs). One of the most abundant DBPs from oxidative ballast water treatment is bromoform (CHBr3), for which we find an average concentration of 894±560 nmol L−1 (226±142 µg L−1) in the undiluted ballast water from measurements and the literature. Bromoform is a relevant gas for atmospheric chemistry and ozone depletion, especially in the tropics where entrainment into the stratosphere is possible. The spread of DBPs in the tropics over months to years is assessed here for the first time. With Lagrangian trajectories based on the NEMO-ORCA12 model velocity field, we simulate DBP spread in the sea surface and quantify the oceanic bromoform concentration and emissions to the atmosphere from ballast water discharge at major harbours in the tropical region of Southeast Asia. The exemplary simulations of two important regions, Singapore and the Pearl River Delta, reveal major transport pathways of DBPs and anthropogenic bromoform concentrations in the sea surface. Based on our simulations, we expect DBPs to spread into the open ocean, along the coast and through advection with monsoon-driven currents into the North Pacific and Indian Ocean. Furthermore, anthropogenic bromoform concentrations and emissions are predicted to increase locally around large harbours. In the sea surface around Singapore, we estimate an increase in bromoform concentration by 9 % compared to recent measurements. In a moderate scenario in which 70 % of the ballast water is chemically treated, bromoform emissions to the atmosphere can locally exceed 1000 pmol m−2 h−1 and double climatological emissions. In the Pearl River Delta all bromoform is directly outgassed, which leads to an additional bromine (Br) input into the atmosphere of 495 kmol Br a−1 (∼42 t CHBr3). For Singapore ports the additional atmospheric Br input is calculated as 312 kmol Br a−1 (∼ 26 t CHBr3). We estimate a global anthropogenic Br input from ballast water into the atmosphere of up to 13 Mmol a−1. This is 0.1 % of global Br input from background bromoform emissions and thus not relevant for stratospheric ozone depletion.

Synthesis of 4‐Substituted Pyrrolo[2, 3‐c]quinolines via Microwave‐Assisted C‐N Bond Formation

AbstractA metal‐free approach for the synthesis of 4‐substituted pyrolo[2, 3‐c]quinoline is reported in this paper. Synthesis of the target molecule started from easily available quinoline and was carried out in five steps. The fused pyrrolo‐quinoline unit was assembled using Bartoli indolization and the crucial final step involving microwave assisted C−N bond formation was carried out by reaction of 4‐chloro‐3H‐pyrrolo[2, 3‐c]quinolines and diverse aliphatic amines, in the presence of N, N’‐diisopropylethylamine (DIPEA). Final molecules were obtained in good yields even in the presence of additional bromine functionality on the quinolines, thus demonstrating the selectivity of the developed coupling procedure and possibility of increasing the product diversity.

Elucidation of the mangicol and neomangicol biosynthetic pathway from the marine fungus Fusarium equiseti CNC-477

While actinomycetes are often regarded as good resources for the discovery of bioactive metabolites, the recent explosion in whole genome sequencing has brought filamentous fungi back into the spotlight as feasible resources for drug discovery programs. The marine-derived fungal strain Fusarium equiseti CNC-477, characterized by the Fenical laboratory, was shown to be a prolific producer of rare sesterterpene (C25) polyols. Mangicols A-G contain an unprecedented spirotricyclic core and possess remarkable anti-inflammatory activity, whereas neomangicols A-C contain a tetracyclic skeleton and exhibit antimicrobial activities. Both classes of molecules contain multiple hydroxylations on the uncyclized prenyl chain and neomangicols A and B contain an additional chlorine or bromine atom, respectively, that is crucial for bioactivity. De novo genome sequencing and assembly has revealed candidate biosynthetic clusters responsible for the synthesis of these sesterterpene polyols. These biosynthetic clusters, a proposed biosynthetic route and the development of alternative platforms for the heterologous production of the mangicols and neomangicols will be presented.

A biochemical multi-species quality model of a drinking water distribution system for simulation and design

Abstract Drinking Water Distribution Systems (DWDSs) play a key role in sustainable development of modern society. They are classified as critical infrastructure systems. This imposes a large set of highly demanding requirements on the DWDS operation and requires dedicated algorithms for on-line monitoring and control to tackle related problems. Requirements on DWDS availability restrict the usability of the real plant in the design phase. Thus, a proper model is crucial. Within this paper a DWDS multi-species quality model for simulation and design is derived. The model is composed of multiple highly inter-connected modules which are introduced to represent chemical and biological species and (above all) their interactions. The chemical part includes the processes of chloramine decay with additional bromine catalysis and reaction with nitrogen compounds. The biological part consists of both heterotrophic and chemo-autotrophic bacteria species. The heterotrophic bacteria are assumed to consume assimilable organic carbon. Autotrophs are ammonia oxidizing bacteria and nitrite oxidizing bacteria species which are responsible for nitrification processes. Moreover, Disinfection By-Products (DBPs) are also considered. Two numerical examples illustrate the derived model’s behaviour in normal and disturbance operational states.

Crystal structure of [Co(N2C2H8)3] [AuBr4]2Br bis(tetrabromoaurate(III))tris(ethylenediamine) cobalt(III) bromide

A double complex salt [Co(N2C2H8)3][AuBr4]2Br is obtained and characterized using single crystal X-ray diffraction analysis. The crystallographic data of C6H24Au2Br9CoN6 are as follows: a = 21.6479(17) A, b = 14.9085(12) A, c = 8.2676(7) A, β = 110.820(2)°, V = 1538.92(12) A3, C2/c space group, Z = 4, d x = 3.602 g/cm3. Square planar coordination of the gold atom in the complex anion is completed to a tetragonal pyramid by an additional bromine atom of the adjacent complex anion at the Au... Br distance of 3.677 A.

Synthesis of novel ageladine A analogs showing more potent matrix metalloproteinase (MMP)-12 inhibitory activity than the natural product

By employing a previously established synthetic scheme, the synthesis described in the title was carried out in order to explore the substituent effects in the pyrrole ring of ageladine A on MMP-12 inhibitory activity. It became evident that a halogen atom (Br or Cl) at the 2-position and an additional bromine atom at the 4-position are highly effective for improving the inhibitory activity. These studies led us to discover three novel ageladine A analogs ( 4a, c, o) showing more potent MMP-12 inhibitory activity than the natural product.

Tropospheric and stratospheric BrO columns over Arrival Heights, Antarctica, 2002

Spectroscopic measurements of BrO using direct sun and zenith sky viewing geometries are combined in an optimal estimation retrieval algorithm to obtain tropospheric and stratospheric columns of BrO. Twenty‐two twilight periods are investigated over Arrival Heights, Antarctica (77.8°S, 166.7°E) during the polar spring period of 2002. This paper presents the first tropospheric and stratospheric BrO column retrievals from UV‐visible ground‐based measurements for a polar location. A direct comparison is made between stratospheric columns retrieved at 80°, 84°, and 88° solar zenith angles (SZA) from the spectroscopic measurements and those calculated by the SLIMCAT three‐dimensional chemical transport model. The ground‐based column BrO observations are consistent with a SLIMCAT stratospheric Bry loading of 21.2 parts per trillion at 20 km. SLIMCAT reproduces the observed sunrise column BrO increase but does not match the sunset observations, which display less variation. The significant warming of the Antarctic polar stratosphere in 2002 led to highly variable stratospheric columns being observed. The observed column BrO decreased with the transition from vortex to extravortex air on 21 September but did not change much following the return of the vortex on 12 October. For the tropospheric column, an almost normal distribution consistent with a “background” of 0.3 ± 0.3 × 1013 molecules cm−2 is observed from the ground (80°, 84°, and 88° for both sunrise and sunset). A statistically significant “bromine explosion” event (at the 2σ level) was detected at the end of October with a tropospheric column of 1.8 ± 0.1 × 1013 molecules cm−2. The measured tropospheric columns are compared with the tropospheric Model of Atmospheric Transport and Chemistry–Max Planck Institute for Chemistry version model. The tropospheric BrO sunrise column observations can only be explained with an additional bromine source other than decomposition of CH3Br and downward transport of long‐lived bromine from the stratosphere. A comparison with the spaceborne Global Ozone Monitoring Experiment (GOME) found the total columns observed from the ground to be 16–25% smaller than the total columns observed by GOME for SZAs between 80° and 88°.

Thermodynamic Property and Relative Stability of 76 Polybrominated Naphthalenes by Density Functional Theory

The fully optimized calculation of naphthalene and 75 polybrominated naphthalenes (PBNs) in the ideal gas phase were carried out at the B3LYP/6-31G* level. The corresponding thermodynamic parameters, including standard enthalpy, standard Gibbs energy, standard entropy, standard heat capacity at constant volume, and standard thermal energy (i.e., the sum of zero-point energy and thermal energy corrections for molecular translation, rotation, and vibration), were calculated according to temperature correction. In addition, the dependences of some thermodynamic parameters on the number and the position of bromine substituent are discussed. With each additional bromine atom being introduced to the PBNs, the increments of standard entropy and standard heat capacity at constant volume are about 41 J·mol-1·K-1 and 17 J·mol-1·K-1, respectively, and the decrease of standard thermal energy is about 48 kJ·mol-1. By designing isodesmic reactions, the standard enthalpy of formation and the standard Gibbs energy of formation were obtained. On the basis of the magnitude of the relative standard Gibbs energy of formation, the relative stability of PBN isomers was theoretically proposed in this work. Furthermore, comparison of the standard formation enthalpies values, obtained from the B3LYP/6-31G* method as well as four semiempirical methods (AM1, MNDO-d, MNDO, and PM3), was made for PBNs.

Sensitivity of ozone to bromine in the lower stratosphere

Measurements of BrO suggest that inorganic bromine (Bry) at and above the tropopause is 4 to 8 ppt greater than assumed in models used in past ozone trend assessment studies. This additional bromine is likely carried to the stratosphere by short‐lived biogenic compounds and their decomposition products, including tropospheric BrO. Including this additional bromine in an ozone trend simulation increases the computed ozone depletion over the past ∼25 years, leading to better agreement between measured and modeled ozone trends. This additional Bry (assumed constant over time) causes more ozone depletion because associated BrO provides a reaction partner for ClO, which increases due to anthropogenic sources. Enhanced Bry causes photochemical loss of ozone below ∼14 km to change from being controlled by HOx catalytic cycles (primarily HO2+O3) to a situation where loss by the BrO+HO2 cycle is also important.

Enzymatic decolorization of sulfonphthalein dyes

The white rot fungus (WRF) Pleurotus ostreatus produced manganese peroxidase (MnP) and manganese-independent peroxidase (MIP) activities during solid state fermentation of wheat straw, a natural lignocellulosic substrate. Most of the sulfonphthalein (SP) dyes were decolorized by MnP at pH 4.0. The higher K m for meta-cresol purple (40 μM) and lower K m for ortho-cresol red (26 μM) for MnP activities explained the preference for the position of methyl group at ortho than at meta on chromophore. Bromophenol blue decolorizing activity was higher at pH 3.5 and decreased as the concentration of Mn II was increased. SP-decolorizing activity was associated not only with MnP but also with MIP. Additional bromine group along with the methyl group on SP chromophores decreases the rate of decolorization. Bromination of sulfonphthalein chromophore makes them the poorer substrate for MnP. This is evident from the higher K m for bromocresol green (117 μM) when compared to bromocresol purple (36 μM) and bromophenol blue (78 μM). The order of preference for the SP dyes as substrate for the MnP-catalyzed decolorizing activity is phenol red > ortho-cresol red > meta-cresol purple > bromophenol red > bromocresol purple > bromophenol blue > bromocresol green and the order of preference for the SP dyes as substrate for the MIP-catalyzed decolorizing activity is bromocresol green > bromophenol blue > bromocresol purple > bromophenol red > meta-cresol purple > ortho-cresol red > phenol red. Inhibition of PR decolorizing activity by NaN 3 provided the evidence of decolorizing activity as an oxidative process.

Bromide content of sea‐salt aerosol particles collected over the Indian Ocean during INDOEX 1999

Bromide can be depleted from sea‐salt aerosol particles in the marine boundary layer (MBL) and converted to reactive gas‐phase species like Br, BrO, and HOBr, which affect ozone chemistry. Air pollution can enhance the bromine release from sea‐salt aerosols and thus inject additional bromine into the MBL. During the winter monsoon the northern Indian Ocean is strongly affected by air pollution from the Indian subcontinent and Asia. As part of the Indian Ocean Experiment (INDOEX), aerosol particles were sampled with stacked filter units (SFU) on the NCAR Hercules C‐130 aircraft during February‐March 1999. We determined the vertical and latitudinal distribution of the major inorganic aerosol components (NH4+, Na+, K+, Mg2+, Ca2+, Cl−, NO3−, SO42−) and the Br− content of the coarse aerosol to examine the role of the bromine release on the gas‐phase chemistry in the marine boundary layer over the tropical Indian Ocean. The aerosol mass and composition varied significantly with air mass origin and sampling location. In the northern part of the Indian Ocean (5°–15°N, 66°–73°E), high concentrations of pollution‐derived inorganic species were found in the marine boundary layer extending from the sea surface to about 1.2 km above sea level. In this layer, the average mass concentration of all aerosol species detected by our technique was comparable to pollution levels observed in industrialized regions. In the Southern Hemisphere (1°–9°S, 66°– 73°E), the aerosol concentrations rapidly declined to remote background levels. A chloride loss from the coarse aerosol particles was observed in parallel to the latitudinal gradient of the non sea salt SO42− burden. In most of the samples, Br− was depleted from the sea‐salt aerosols. However, we found an enrichment in bromide in aerosols affected by air masses originating over strong pollution sources in India (Bombay, Calcutta). In these cases the additional pollution‐derived Br from organo‐halogen additives in petrol outweighs the release of sea‐salt bromine.

Vapor Pressures of the Polybrominated Diphenyl Ethers

The supercooled liquid vapor pressures PL of 23 polybrominated diphenyl ether congeners were determined as a function of temperature with a gas chromatographic retention time technique. PL at 298.15 K ranged from 0.1 Pa for monobrominated diphenyl ethers to 10-6 Pa for heptabrominated diphenyl ethers. The halogen substitution pattern was found to influence PBDE vapor pressure, indicating that congeners with bromine substitutions in the ortho positions to the ether-link have higher vapor pressures. The enthalpy of vaporization ΔvapH for the 23 PBDE congeners ranged from (−67 to −116) kJ/mol, decreasing with each additional bromine substitution by about (7 to 8) kJ·mol-1. ΔvapH was also found to be influenced by the number of ortho bromines. Using a Junge−Pankow approach, the fraction of chemical adsorbed to aerosols as a function of temperature was estimated for three congeners and used to speculate on the likely environmental behavior of these chemicals.

Absolute Rate Constants for the Reactions of Cl Atoms with CH3Br, CH2Br2, and CHBr3

The rate constants for the reactions of chlorine atoms with the complete series of the three bromomethanes CH3Br (1), CH2Br2 (2), and CHBr3 (3) were measured in a very low pressure reactor, employing a microwave discharge for the generation of Cl atoms with mass spectrometric detection of reactants and products. The experiments were performed in the temperature range 273−363 K and at total pressures ∼1 mTorr. The reactions proceed via hydrogen atom transfer leading to HCl product and the corresponding bromomethyl radicals. Their rate constant expressions are (in cm3 molecule-1 s-1): k1 = (1.66 ± 0.14) × 10-11 exp(−1072 ± 46/T), k2 = (0.84 ± 0.15) × 10-11 exp(−911 ± 101/T), and k3 = (0.43 ± 0.11) × 10-11 exp(−809 ± 142/T). The activation energy of the reaction decreases with additional bromine substitution, which is attributed to the gradual weakening of the corresponding C−H bond strength. Ab initio theoretical calculations performed at the MP2/6-31++G(2d,2p) level of theory suggest C−H bond strengths fo...

Marine Alkaloids. 19. Three New Alkaloids, Securamines E−G, from the Marine Bryozoan Securiflustra securifrons

Three new halogenated indole−imidazole alkaloids, securamines E (1), F (2), and G (3), have been isolated from the marine bryozoan Securiflustra securifrons. Their structures were determined by NMR and mass spectrometry. The new alkaloids, 1−3, can all be related to the earlier reported securamine C (4). Compound 1 has an additional bromine substituent at the indole ring system compared to 4; 2 and 4 are diastereomers differing in configuration at one of the four asymmetric carbon atoms; and 3 is a hydrogenated form of 4.

Oligomeric Rare-Earth-Metal Halide Clusters. Three Structures Built of (Y(16)Z(4))Br(36) Units (Z = Ru, Ir).

Suitable reactions in sealed Nb tubing at 850-950 degrees C gave good yields of a family of oligomeric cluster phases that were characterized by single-crystal X-ray diffraction means. The basic Y(16)Z(4) units ( approximately &fourmacr; symmetry) can be derived from 2+2 condensation of centered Y(6)Br(12)Z-type clusters or as tetracapped truncated tetrahedra Y(16) that are centered by a large tetrahedral Z(4). These are surrounded by 36 bromine atoms which bridge edges or cap faces of the Y(16)Z(4) nuclei and, in part, bridge to metal atoms in other clusters. The principal bonding appears to be Y-Z and Y-Br, with weaker Y-Y (&dmacr; approximately 3.70 Å) and negligible Z-Z interactions. The phase Y(16)Br(20)Ru(4) (P4(2)/nnm, Z = 2; a = 11.662(1) Å, c = 16.992 (2) Å) is isostructural with Y(16)I(20)Ru(4) and with the new Sc(16)Br(20)Z(4) (Z = Fe, Os). Syntheses only in the presence of Ir and ABr-YBr(3) fluxes (A = K-Cs) produce Y(16)Br(24)Ir(4) (Fddd, Z = 8; a = 11.718(3) Å, b = 22.361(7) Å, c = 44.702(2) Å), in which the electron-richer Ir interstitials are compensated by four additional bromine atoms and altered bridging between macroclusters. Larger amounts of YBr(3) yield a third example, Y(20)Br(36)Ir(4) (Y(16)Br(24)Ir(4).4YBr(3), I4(1)a, Z = 4; a = 12.699(1) Å, c = 45.11(1) Å). Here infinite zigzag chains of YBr(6/2) octahedra that share cis edges lie between and bridge to the Y(16)Ir(4) clusters. All of these phases contain 60-electron, closed-shell macroclusters. Y(16)Br(20)Ru(4) and Y(20)Br(36)Ir(4) were found to exhibit temperature-independent (Van Vleck) paramagnetism with values typical of those found for other rare-earth-metal, zirconium, niobium, and tantalum cluster halides.

Studies on the breakdown of organoselenium compounds in a hydrobromic acid–bromine digestion system

The chemical role played by bromine in HBr solution was investigated in the breakdown of both the trimethylselenonium ion and selenomethionine. Hydride generation and gas chromatography, both coupled with atomic fluorescence detection, polarography, and 1H and 77Se nuclear magnetic resonance spectrometry, were employed in order to collect information on the intermediate and final selenium compounds. Trimethylselenonium and selenomethionine were quantitatively converted into inorganic SeIV in hot concentrated HBr, but only in the presence of a large excess of bromine with respect to organoselenium. In the absence of additional bromine and under a stream of inert gas, the digestion of trimethylselenonium resulted in a 95% loss of selenium from the solution. Dimethyl diselenide and dimethyl selenide were detected in the headspace gases of the digestion apparatus. Under the same conditions, selenomethionine gave a result of about 70% of selenium caught in the solution. In this instance experimental evidence indicated that the major selenium component in the headspace gases of the digestion apparatus was methaneselenol. The roles played by bromine and HBr in the conversion of organoselenium into inorganic SeIV were identified as (i) the oxidative addition of bromine to divalent selenium to form bromoselenonium intermediates and (ii) the dealkylation of selenonium compounds by the bromide ion.

Atropisomerism in (±)-7-methyl- and -phenyl-substituted dinaphtho[2,1- b;1′,2′- d]phospholes and dinaphth[2,1- b;1′,2′- d]arsoles

The reaction of 2,2′-dilithio-1,1′-binaphthyl with RECl 2 (E = P or As; R = Me or Ph) affords the corresponding (±)-7-substituted dinaphtho[2,1- b;1′,2′- d]phospholes and dinaphth[2,1- b:1′,2′- d]arsoles. The molecules are fluxional on the NMR time scale with similar barriers between the conformational isomers (atropisomers) for the four compounds, vis. † G‡ = 56 ± 1 (243 K, ER = PMe), 56 ± 1 (254 K, ER = PPh), 65 ± 1 (287 K, ER = AsMe), 59 ± 1 (259 K, ER = AsPh) kJ mol −1. An X-ray diffraction study of ( S)-7-phenyldinaphth[2,1- b;1′,2′- d]arsole which crystallized out by spontaneous resolution reveals appreciable bending of the distorted naphthyl residues away from each other. The asymmetric unidentates (±)-L coordinate to iron(II) in complexes of the type [(η 5-C 5H 5)[1,2-C 6H 4(PMePh) 2]FeL]PF 6 with a small degree of enantioselection of one atropisomer of (±)-L. The complexes of the arsines are stable on the NMR time scale in CD 2Cl 2 at 20°C, but the corresponding phosphine complexes require cooling for observation of diastereomerism. The 7-methyl substituted arsole is demethylated by bromine giving the corresponding 7-bromo compound, which, in turn, is converted by additional bromine into configurationally stable (±)-[2-(2′-bromo-1,1′-binaphthyl)]dibromoarsine.

Transbilayer distribution of bromine in fluid bilayers containing a specifically brominated analog of dioleoylphosphatidylcholine

We describe in this paper the transbilayer distribution of the bromines of the specifically halogenated phospholipid 1-oleoyl-2-(9,10-dibromostearoyl)-sn-glycero-3- phosphocholine (OBPC). The distribution was determined by X-ray diffraction of oriented multilayers of mixtures of OBPC and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) at 66% relative humidity by the general approach of Franks et al. (1978) [Nature 276, 530-532]. The bromine distribution of OBPC in the fluid L alpha phase is described accurately by a pair of Gaussian functions located 7.97 +/- 0.27 A from the center of the bilayer with l/e half-widths of 4.96 +/- 0.62 A. We find that OBPC bilayers are accurately described as DOPC bilayers with an additional bromine distribution centered at the position of the double bond of DOPC and conclude that OBPC is an excellent structural isomorph for DOPC under the conditions of these experiments. The distribution obtained is the complete and fully resolved transbilayer image of the halogen label because the broad distribution of the bromines is due entirely to thermal disorder and not to experimental limitations [Wiener, M. C., & White, S. H. (1991a) Biophys. J. 59, 162-173]. The observed width of the bromine distribution indicates that virtually all of the hydrocarbon interior is accessible to the bromines. The distance between the bromine/double-bond position and the headgroup phosphate position was determined from one-dimensional Patterson maps and found to be approximately 12 A. The application of accurately determined bromine distributions to the quantitative interpretation of fluorescence quenching experiments is discussed. A method for the self-consistent global analysis of diffraction data from mixtures that permits the use of data sets with different instrumental scale factors is developed in an Appendix.

Regioselective halo- and carbodesilylation of (trimethylsilyl)-1-methylpyrazoles

The isomeric 3-, 4-, and 5-(trimethylsily1)- as well as the 3,4-, 3,5-, and 4,5-bis(trimethylsilyl)-l-methylpyrazoles (2,7,3,5,9,a nd 10, respectively) are obtained by methylation of the corresponding (trimethylsily1)-1H-pyrazoles or by silylation of Grignard or lithio derivatives of appropriate 1-methylpyrazoles with chlorotrimethylsilane. 5 and 10 are halodesilylated regioselectively by Br2 or ICl in the 4-position, yielding 13 and 15. With additional bromine, these monobromo compounds suffer exclusively bromodesilylation to give 3,4- and 4,5-dibromo-lmethylpyrazole (14 and 16, respectively). These findings are in accord with the electrophilic substitution reactivity indices for 1-methylpyrazole (8) and with ipso-directing influence of the MeBSi group. The reaction of 5 with Iz, unexpectedly, attacks preferentially at the 3-position. Regioselective carbodesilylation in the 5-position is observed in the fluoride-catalyzed reactions of 3, 9, and 10 with carbon electrophiles. The high regiospecificity of this reaction is rationalized in terms of carbanion stabilization at the individual pyrazole positions.

Some observations concerning the bromination of imidazole derivatives in chloroform

The bromination of imidazole. N-methylimidazole, benzimidazole and N-methyl- benzimidazole in chloroform has been studied. Imidazole gives with half mole of bromine a C-polybromoderivative together with imidazole hydrobromide which by treatment with additional bromine gives a red dicoordinate complex of unipositive bromine, N-methylimidazole gives a similar result. Benzimidazole also gives a dicoordinate complex but, probably, the intermediate is the N-bromobenzimidazole hydrobromide: no C-bromination is detected in this case. Under similar conditions N-methylbenzimidazole gives a 1:1 complex of the n-donor type. The reasons for these differences are discussed.