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An efficient [3 + 2] cycloaddition reaction involving vinyl acetates with tri/difluoroacetohydrazonoyl bromides has been established. This reaction provides an efficient method for synthesis of highly valuable ring-fused fluoroalkyl pyrazoles in moderate to good yields under mild reaction conditions, exhibiting remarkable regioselectivity and broad substrate scopes. The strategy further demonstrated that tri/difluoroacetohydrazonoyl bromides are effective tri/difluoromethyl building blocks for synthesis of fluoroalkyl heterocycle compounds. [Display omitted] • Tri/difluoromethyl pyrazoles were synthesized using tri/difluoromethylacetohydrazonoyl bromides as building blocks. [ABSTRACT FROM AUTHOR]

The potential of compound-specific stable isotope analysis (CSIA) to characterize biotransformation of brominated organic compounds (BOCs) was assessed and compared to chlorinated analogues. Sulfurospirillum multivorans and Desulfitobacterium hafniense PCE-S catalyzed the dehalogenation of tribromoethene (TBE) to either vinyl bromide (VB) or ethene, respectively. Significantly lower isotope fractionation was observed for TBE dehalogenation by S. multivorans (ε C = −1.3 ± 0.2‰) compared to D. hafniense (ε C = −7.7 ± 1.5‰). However, higher fractionation was observed for dibromoethene (DBE) dehalogenation by S. multivorans (ε C = −16.8 ± 1.8‰ and −21.2 ± 1.6‰ for trans - and cis -1,2- (DBE) respectively), compared to D. hafniense PCE-S (ε C = −9.5 ± 1.2‰ and −14.5 ± 0.7‰ for trans -1,2-DBE and cis- 1,2-DBE, respectively). Significant, but similar, bromine fractionation was observed for for S. multivorans (ε Br = −0.53 ± 0.15‰, −1.03 ± 0.26‰, and −1.18 ± 0.13‰ for trans -1,2-DBE, cis- 1,2-DBE and TBE, respectively) and D. hafniense PCE-S (ε Br = −0.97 ± 0.28‰, −1.16 ± 0.36‰, and −1.34 ± 0.32‰ for cis -1,2-DBE, TBE and trans- 1,2 - DBE, respectively). Variable C Br dual-element slopes were estimated at Λ (ε C /ε Br ) = 1.03 ± 0.2, 17.9 ± 5.8, and 29.9 ± 11.0 for S. multivorans debrominating TBE, cis- 1,2-DBE and trans- 1,2-DBE, respectively, and at 7.14 ± 1.6, 8.27 ± 3.7, and 8.92 ± 2.4 for D. hafniense PCE-S debrominating trans- 1,2-DBE, TBE and cis- 1,2-DBE, respectively. A high variability in isotope fractionation, which was substrate property related, was observed for S. multivorans but not D. hafniense , similar as observed for chlorinated ethenes, and may be due to rate-limiting steps preceding the bond-cleavage or differences in the reaction mechanism. Overall, significant isotope fractionation was observed and, therefore, CSIA can be applied to monitor the fate of brominated ethenes in the environment. Isotope effects differences, however, are not systematically comparable to chlorinated ethenes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Mizoroki-Heck coupling based new method of polymerization of a-bromostyrene derivatives is developed to synthesize substituted poly(phenylacetylene)s. • Branched poly(phenylacetylene)s are synthesized by using bifunctional vinyl halide monomers. • End-group functionalization of synthetic poly(phenylacetylene)s is achieved via Mizoroki-Heck coupling reaction of terminal vinyl bromide and alkene functionalities. Polyacetylene and its derivatives are a class of traditional conjugated polymers that started the era of conducting plastics. In this paper, we develop a new approach of synthesizing substituted poly(phenylacetylene)s through Mizoroki-Heck coupling of vinyl bromides. A series of α-bromostyrene derivatives are synthesized and used as the monomers for the polycoupling reaction. It is found that K 2 CO 3 is the effective base while Et 3 N shows almost no catalytic reactivity. Gel permeation chromatography (GPC) results indicate that the molecular weight distribution is broad, which is typical for step growth polymerization. A kinetic study shows that electron withdrawing group on the phenyl ring increase the polymerization rate of the corresponding monomer. Furthermore, incorporating both aryl and vinyl halides into a single vinyl monomer allows the synthesis of branched polyacetylene possessing oligo(phenylene vinylene) at the branch points. The current approach may serve as a new tool for the molecular engineering of substituted polyacetylene materials. [ABSTRACT FROM AUTHOR]

A molecularly imprinted mesoporous silica-based fluorescent sensor was prepared using a tetraphenylethene derivative (TBPE) as a signal transducer. Diethylstilbestrol (DES) was chosen as a target molecule and was connected to two triethoxysilane groups via thermally reversible urethane bonds. DES imprinted cavities with two-point binding sites were formed between the pores of the mesoporous silica by the sol-gel reaction and subsequent removal of DES. TBPE was selectively introduced to the pore surface. TBPE-grafted, DES imprinted mesoporous silica nanoparticle (TBPE-DIMSNP) showed a specific binding ability for the target template. The degree of fluorescence quenching of TBPE-DIMSNP was proportional to the concentration of DES. The sensitivity and selectivity of TBPE-DIMSNP were estimated by the Stern-Volmer equation. TBPE-DIMSNP displayed a much larger Stern-Volmer quenching constant for DES than for DES analogs with a high molecular imprinting factor. TBPE-DIMSNP also exhibited a great recovery of its initial fluorescence intensity even after several extraction and rebinding cycles. [ABSTRACT FROM AUTHOR]

This work presents experimental results on the inhibition performance of kinetic hydrate inhibitors (KHIs) of structure-II hydrates. The studied KHIs, namely derivatives of copolymers of N -vinylcaprolactam (VCap) and alkylimidazolium salts, were synthesized at the Mexican Petroleum Institute with the objective of producing copolymers with higher cloud points than that exhibited by the poly( N -vinylcaprolactam) homopolymer. Three experimental methods were used to evaluate the hydrate inhibition performance of the synthesized copolymers: the capacity to inhibit the formation of tetrahydrofuran (THF) hydrates (under atmospheric pressure and at a temperature of −0.5 °C; i.e., a subcooling for THF hydrates of about 3.4 °C); the capacity to inhibit the formation of natural gas hydrates under high pressure (about 6 MPa) and low temperature conditions (about 1 °C; i.e. a subcooling of 16 °C for the studied natural gas sample); and the determination of the cloud point temperature of the studied copolymers in aqueous systems of varying salinity (under atmospheric pressure and temperatures ranging from 2 to 81 °C). The inhibition performance and the high solubility (in highly saline aqueous systems) of the synthesized copolymers seems to indicate that these compounds can be considered as promising low dosage inhibitors to prevent or delay the formation of hydrates during the production and transport of hydrocarbons. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dissolution of poly-Si in H 3 PO 4 consists of unstable suboxide formation and its dissolution. • Epoxy and vinyl group additives in H 3 PO 4 passivate poly-Si surface. • Epoxy and vinyl group additives suppress dissolution of poly-Si in H 3 PO 4. • Additives with Si–O bond as well as epoxy or vinyl group in H 3 PO 4 selectively remove Si 3 N 4 layers at multi-stacked Si 3 N 4 /SiO 2. This work investigates the mechanism of polycrystalline silicon (poly-Si) dissolution in H 3 PO 4. The etching rate of poly-Si was more rapid than that of silicon dioxide (SiO 2) in H 3 PO 4 solution, because poly-Si surface possesses unstable Si1+, Si2+, and Si3+ states – rather than Si4+, which is more stable. Additives such as epichlorohydrin, 1,2-epoxy-3-phenoxypropane, vinyl bromide, and phenyl vinyl ether with epoxy or vinyl groups were introduced into the H 3 PO 4 to passivate the poly-Si surface. This significantly increased the presence of the Si4+ state and provided hydrophobic functional groups on the poly-Si surface to reduce the wettability of the poly-Si surface. The introduction of these additives significantly reduced the etching rate of poly-Si. 3-glycidyloxypropyl trimethoxysilane, 3-glycidyloxypropyl dimethoxymethylsilane, allyltrimethoxysilane, and vinyltrimethoxysilane with Si–O bonds, as well as epoxy or vinyl groups in their molecular structures, were demonstrated to suppress the etching rate of both SiO 2 and poly-Si. The introduction of these additives to H 3 PO 4 promoted the selective removal of silicon nitride (Si 3 N 4) layers from multi-layered Si 3 N 4 /SiO 2 trench structures without the loss of either poly-Si or SiO 2. [ABSTRACT FROM AUTHOR]

Vinyl bromides were subjected to the trifluoroethoxylation reactions with copper reagent [(phen) 2 Cu][OCH 2 CF 3 ] at 80 °C in DMF with the presence of NaO t -Bu to afford the trifluoroethyl vinyl ethers in good yields. A range of functional groups, such as cyano, nitro, alkoxy, trifluoromethyl, halide, and heterocyclic groups were well tolerated. This approach is also amenable to being performed out on gram scales. [ABSTRACT FROM AUTHOR]

The adsorption and desorption of Cd onto Shewanella oneidensis bacterial cells with and without blocking of sulfhydryl sites was measured in order to determine the effect of metal loading and to understand the role of sulfhydryl sites in the adsorption reactions. The observed adsorption/desorption behaviors display strong dependence on metal loading. Under a high loading of 40 μmol Cd/g bacterial cells, blocking the sulfhydryl sites within the cell envelope by exposure of the biomass to monobromo(trimethylammonio)bimane bromide (qBBr) does not significantly affect the extent of Cd adsorption, and we observed fully reversible adsorption under this condition. In contrast, under a low metal loading of 1.3 μmol Cd/g bacterial cells, the extent of Cd adsorption onto sulfhydryl-blocked S. oneidensis cells was significantly lower than that onto untreated cells, and only approximately 50–60% of the adsorbed Cd desorbed from the cells upon acidification. In conjunction with previous EXAFS results, our findings demonstrate that Cd adsorption onto S. oneidensis under low metal loading conditions is dominated by sulfhydryl binding, and thus is controlled by a distinct adsorption mechanism from the non-sulfhydryl site binding which controls Cd adsorption under high metal loading conditions. We use the data to develop a surface complexation model that constrains the values of the stability constants for individual Cd-sulfhydryl and Cd-non-sulfhydryl bacterial complexes, and we use this approach to account for the Cd adsorption behavior as a function of both pH and metal loading. This approach is crucial in order to predict metal adsorption onto bacteria under environmentally relevant metal loading conditions where sulfhydryl binding sites can dominate the adsorption reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Allylic alcohols may be converted directly to α-bromo-α,β-unsaturated ketones in a single reaction. • This procedure employs TEMPO, tetraethylammonium bromide and oxone, an environmentally friendly oxidant. • Primary allylic alcohols may be converted to α-bromo-α,β-unsaturated aldehydes under these conditions. Allylic alcohols may be converted directly to α-bromo-α, β-unsaturated ketones in a single reaction with a mixture of TEMPO, Oxone and tetraethylammonium bromide. The process proceeds first through the oxidation of the alcohol to the ketone, followed by dibromination of the alkene with bromine that is generated from Oxone and tetraethylammonium bromide. Quenching the reaction with triethylamine then facilitates an elimination and forms the vinyl bromide. The presence of electron-donating groups on the aromatic ring leads to faster reactions and higher yields. Alternatively, substrates decorated with electron withdrawing groups on the aromatic ring are slower to oxidize. This method provides a rapid means to access these bromoalkenes using conditions that are operationally simple with reagents that are stable and easy to handle. [ABSTRACT FROM AUTHOR]

A metal-free regioselective hydrobromination of alkynes has been developed to provide the Markovnikov-type vinyl bromides in good yields using dibromomethane/N,N-dimethylaniline as in-situ 'HBr' source. This protocol also represents an elegant example of the activation of sp² CH and CBr bonds in one pot, in which 'HBr' is generated and transferred under mild metal-free conditions. D-incorporated experiments were employed to investigate the reaction mechanism and a plausible reaction path was proposed. [ABSTRACT FROM AUTHOR]

Abstract: A one-pot base-mediated reaction of azides and β- or α-vinyl bromides has been reported. The effects of bases and solvents have been investigated in the process. A variety of 1,5-disubstituted triazoles were prepared in low to good yields. Further studies reveal that the corresponding alkynes were produced as intermediates via elimination reaction. Under the same reaction conditions, the reactions of alkyl alkynes with phenyl azide would give 1,5-disubstituted 1,2,3-triazoles. [Copyright &y& Elsevier]

Abstract: A nickel-catalyzed intramolecular addition of vinyl or aryl bromides to ketoamides has been developed. The reactions proceeded efficiently with Ni(bpy)Br2 as a catalyst and zinc powder as reducing agent, affording 3-hydroxypyrrolidinones, 3-hydroxyoxindoles, and dihydroquinolinones as important heterocyclic compounds in good to excellent yields. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: A palladium-catalyzed tandem reaction of 2-alkynylaniline with 2-alkynylvinyl bromide provides an efficient route for the assembly of cyclopenta[c]quinolin-3-ols. A double insertion of triple bonds is the key step during the transformation. [Copyright &y& Elsevier]

Abstract: A time-resolved study of the infrared fluorescence emission produced in the infrared multiphoton dissociation of vinyl bromide at different experimental conditions has been carried out. Two different regimes, namely unimolecular and collisional, have been identified and characterized through the parent vinyl bromide and the HBr and C2H2 photoproducts emissions. In the pressure interval studied, the formation of HBr has been determined to be mainly unimolecular, while the C2H2 is produced through a collisionally assisted photodecomposition process. The collisional regime is explained in terms of the 3-centre elimination channel while the unimolecular regime is ascribed to the 4-centre mechanism. Relaxation rate constants for both the vibrationally excited HBr by vinyl bromide and by Ar and for vibrational excited VBr by unexcited VBr, are reported. [Copyright &y& Elsevier]

[Co(η4-C4Ph4)(η5-C5H4C≡C–CHO)], 4a, has been prepared from [Co(η4-C4Ph4)(η5-C5H4CHO)], 1a, by reactions similar to those used previously to convert [Fe(η5-C5H5)(η5-C5H4CHO)], 1b, to [Fe(η5-C5H5)(η5-C5H4C≡C–CHO)], 4b, i.e. via the dibromoethene [Co(η4-C4Ph4)(η5-C5H4CHᆖCBr2)], 2a, and alkyne [Co(η4-C4Ph4)(η5-C5H4C≡CH)], 3a. Both 4a and 4b undergo the normal aldehyde reactions with malononitrile and 2,4-dinitrophenylhydrazines to give their respective condensation products [Co(η4-C4Ph4){η5-C5H4C≡C–CHC(CN)2}], 5a, and [Fe(η5-C5H5){η5-C5H4C≡C–CHᆖC(CN)2}], 5b; [Co(η4-C4Ph4){η5-C5H4C≡C–CHᆖN–N(H)C6H3(NO2)2-2,4}], 6a, and [Fe(η5-C5H5){η5-C5H4C≡C–CHᆖN–N(H)C6H3(NO2)2-2,4}], 6b, as separable mixtures of syn- and anti-isomers; and the anti-isomers of [Co(η4-C4Ph4){η5-C5H4C≡C–CHᆖN–N(Me)C6H3(NO2)2-2,4}], 7a, and [Fe(η5-C5H5){η5-C5H4C≡C–CHN–N(Me)C6H3(NO2)2-2,4}], 7b. With [Fe2(η-C5H5)2(CO)2(μ-CO)(μ-CMe)][BF4] 4a and 4b form blue-green [Fe2(η-C5H5)2(CO)2(μ-CO)(μ-C–CHᆖCH-C≡C–C5H4-η5)Co(η4-C4Ph4)][BF4], [8a][BF4], and black [Fe2(η-C5H5)2(CO)2(μ-CO)(μ-C–CHᆖCH–C≡C–C5H4-η5)Fe(η5-C5H5)][BF4], [8b][BF4] salts. 4a and 4b also react with the Wittig reagent [Fe(η5-C5H5)(η5-C5H4–CH2PPh3)][I]/nBuLi to give mixtures of Z and E-[Co(η4-C4Ph4)(η5-C5H4–C≡C–CHᆖCH–C5H4-η5)Fe(η5-C5H5)], 9a, and [Fe(η5-C5H5)(η5-C5H4–C≡C–CHᆖCH–C5H4-η5)Fe(η5-C5H5)], 9b, which are separable for 9b but not 9a. The Wittig reagent obtained from [Co(η4-C4Ph4)(η5-C5H4–CH2PPh3)][Cl]/nBuLi failed to react with 4a or 4b, but the reaction of 4a with [ClCH2PPh3][Cl]/tBuOK gives very low yields of one expected product, E-[Co(η4-C4Ph4)(η5-C5H4–C≡C–CHᆖCH–C5H4-η5)Co(η4-C4Ph4)], E-10a, together with a number of other unidentified compounds. The IR, 1H NMR and 13C NMR, and UV/Vis spectra of 4–9 are reported, assigned and discussed. They confirm that 4–9 are Donor–π–Acceptor complexes in which Co(η4-C4Ph4)(η5-C5H4–) is a weaker donor than Fe(η5-C5H5)(η5-C5H4–), the acceptor strength increases for Acceptor  CHᆖCHFc < CHᆖN–N(R)C6H3(NO2)2-2,4 < CHO < CHC(CN)2 < (–CHᆖCH–Cμ+)(μ-CO)(CO)2Fe2(η5-C5H5)2, and that an ethyne linker, π = CC, is less effective than an ethene linker, π = CHᆖCH, in promoting electronic communication between the Donor and Acceptor. The molecular structures of 2a, 3a, 4a, 4b, 5b, syn-6a, syn-6b (two crystal forms) and anti-7b have been determined by X-ray diffraction. They have normal molecular dimensions, and the C5H4–C≡C–CHY moiety does not deviate greatly from planarity with angles between the C5H4 and C–C(H)Y planes of 4.2–19.6°. This contrasts with the structures of Fc–C≡C–R (R = aryl) complexes where the C5H4 and aryl planes are orthogonal or close to it. The electrochemistry of 3a/3b, 4a/4b, 5a/5b, syn-6a/6b, anti-7a/7b, E/Z-9a, Z-9b, E-9b and [Co(η4-C4Ph4)(η5-C5H4–C≡C–C6H5)] has been studied. The Co(η4-C4Ph4)(η5-C5H4–) complexes undergo reversible 1e oxidations at higher E° than their Fe(η5-C5H5)(η5-C5H4–) counterparts with E° increasing as the electron-withdrawing ability of the acceptor group increases. Furthermore, like their ferrocenyl counterparts, the alkyne derivatives [Co(η4-C4Ph4)(η5-C5H4–CC–X)] are oxidised at a more positive E° than the alkene complexes [Co(η4-C4Ph4)(η5-C5H4–CHᆖCH–X)]. The UV/Visible spectrum of the oxidized species [Co(η4-C4Ph4)(η5-C5H4–C≡C–C6H5)]+ shows an absorption band at 960 nm due to a C6H5 → Co(η4-C4Ph4)(η5-C5H4–) charge transfer transition; its equivalent in the spectrum of [Fe(η5-C5H5)(η5-C5H4–C≡C–C6H5)]+ is found at 797 nm. This implies that {Co(η4-C4Ph4)(η5-C5H4–)}+ is a stronger acceptor than {Fe(η5-C5H5)(η5-C5H4–)}+. [ABSTRACT FROM AUTHOR]

Abstract: Vinyl bromides derived from 2-alkylidene-4-oxothiazolidines represent a class of vinyl halides, which readily undergo a bromophilic attack by a range of nucleophiles. With Ph3P, AcS−, CN−, I−, F−, Ac2CH− and N3 − the attack ends up with reductive debromination, whereas the bromine substitution takes place with KSCN. When acetate anion and organic bases, such as pyridine, Et3N or morpholine, are employed as nucleophiles the initial bromophilic attack is followed by bromine migration to the C(5) position of the ring, allowing the C(5) functionalization of this heterocyclic system. [ABSTRACT FROM AUTHOR]

Abstract: The suitability of a granulated zero valent iron (ZVI) permeable reactive barrier (PRB) remediation strategy was investigated for tribromoethene (TriBE), cis-1,2-dibromoethene (c-DBE), trans-1,2-dibromoethene (t-DBE) and vinyl bromide (VB), via batch and large-scale column experiments that were subsequently analysed by reactive transport modelling. The brominated ethenes in both batch and large-scale column experiments showed rapid (compared to controls and natural attenuation) degradation in the presence of ZVI. In the large-scale column experiment, degradation half-lives were 0.35 days for TriBE, 0.50 days for c-DBE, 0.31 days for t-DBE and 0.40 days for VB, under site groundwater flow conditions, resulting in removal of brominated ethenes within the first 0.2 m of a 1.0 m thick ZVI layer, indicating that a PRB groundwater remediation strategy using ZVI could be used successfully. In the model simulations of the ZVI induced brominated ethene degradation, assuming a dominant reductive β-elimination pathway via bromoacetylene and acetylene production, simulated organic compound concentrations corresponded well with both batch and large-scale column experimental data. Changes of inorganic reactants were also well captured by the simulations. The similar ZVI induced degradation pathway of TriBE and TCE suggests that outcomes from research on ZVI induced TCE remediation could also be applied to TriBE remediation. [Copyright &y& Elsevier]

Abstract: We present a comparison between the theoretical and experimental 1H and 13C chemical shifts of molecules 1–5. In order to compute the chemical shifts, it was necessary to calculate the geometric parameters for the cited alcohols considering in any case the level of theory used in the chemical shift treatment. Thus, RHF ab initio and DFT with at least 6-31G(d) basis sets were used. The geometry parameters of alcohol 1 compare well with X-ray data. The theoretical chemical shifts were obtained using the GIAO method in association with RHF ab initio and DFT levels of theory with at least 6-31G(d) basis sets. Associations with RHF ab initio geometry and DFT levels of theory for the GIAO calculations were also tested. This data set indicates that there are problems of geometric character in the calculation of the brominated vinylic system. On the other hand, the calculations for the nortricyclenic cycloropane ring are in good agreement with experimental findings. [Copyright &y& Elsevier]

The title compounds are prepared via a two step procedure involving a transesterification between a diol and diethyl phosphite followed by a palladium-catalyzed coupling of the so-obtained cyclic phosphite with vinyl bromide. Theoretical DFT calculations have been performed on phosphonate and phosphite anions models in order to estimate stereoelectronic effects in five-membered and six-membered ring compounds. [Copyright &y& Elsevier]

The gas-phase infrared spectrum of natural CH2&z.dbnd6;CHBr has been investigated in the ν6 band region near 1258 cm−1, at a resolution of about 0.002 cm−1, using a tunable diode laser spectrometer. This vibration of symmetry species A′ yields an a/b hybrid band exhibiting predominant characteristics of the a-type component. Spectral analysis resulted in the assignment of 359 (J≤31, Ka≤7) and 351 (J≤50, Ka≤6) transitions of the ν6 fundamental of 79Br and 81Br isotopomers, respectively, whose band origin is separated by 0.0207 cm−1. The assigned transitions, fitted using Watson''s A-reduction Hamiltonian in the Ir representation, yielded upper state constants up to the quartic coefficients for both the isotopic species. The ν6 vibration is locally perturbed by a second order a-type Coriolis resonance with the ν9+ν11 state and the coupling constant as well as the band origin for the perturber were determined. [Copyright &y& Elsevier]

The first total synthesis of aplysinoplide B has been achieved. The synthetic highlight of our approach includes sp 2 –sp 3 Suzuki–Miyaura cross coupling of a vinyl bromide with an alkyl 9-BBN derivative. The vinyl bromide was efficiently synthesized from the disubstituted Z -alkene utilizing a one-pot regioselective bromination. Through the synthetic studies, the absolute stereochemistry at the C4 position of naturally occurring aplysinoplide B was established as an R configuration. [ABSTRACT FROM AUTHOR]

• Red light irradiation of O 3 led to the reaction of O(3P) with C 2 H 3 Br and C 2 H 3 F. • The product yield and distribution were quite different with C 2 H 3 Br and C 2 H 3 F. • A triplet biradical is proposed as the first intermediate in the 625 nm reaction. • 254 nm irradiation led to ketene and bromoketene with C 2 H 3 Br + o 3. • Ketene and fluoroketene were not observed with 254 nm irradiation of C 2 H 3 F + O 3. [Display omitted] A study of the photolytically-induced reactions of ozone with vinyl bromide and vinyl fluoride, H 2 C CHX (X = F , Br), in argon matrixes is described, after either red LED (625 nm) or Hg pen lamp (254 nm) irradiation. Products were observed using infrared spectroscopy and identification was aided by 18O labeling experiments. The experimental work was supported by extensive DFT calculations. For vinyl bromide, bromoacetaldehyde was the dominant product despite the fact that acetyl bromide was calculated to be the most energetically favored product. Lesser amounts of bromooxirane and possibly bromovinyl alcohol were observed. These results are in agreement with an earlier study of the photochemical reaction of ozone with vinyl chloride. In contrast, the overall product yield with vinyl fluoride was much lower. Fluorooxirane was the main product with only a hint of fluoroacetaldehyde despite that fact that fluorooxirane was calculated to be higher in energy than either acetyl fluoride or fluoroacetaldehyde. [ABSTRACT FROM AUTHOR]

• The hydrodebromination of 1,1-dibromoalkenes via visible light catalysis. • A new method for the synthesis of vinyl bromides derivatives. • Broad scope of the substrates, moderate to excellent yields, simple operation and mild conditions. Vinyl bromides are versatile synthetic intermediates and widely applied in organic synthesis and pharmaceuticals. Herein, a hydrodebromination reaction of 1,1-dibromoalkenes was established via visible light catalysis. A variety of structurally different vinyl bromides were obtained in moderate to excellent yields. [ABSTRACT FROM AUTHOR]

The biofilm formation of Pseudomonas aeruginosa (P. aeruginosa) is regulated by a phenomenon of quorum sensing (QS). With 5-hydroxyl-3,4-halogenated-5 H -furan-2-ones as beginning, analogs bearing alkyl chains, vinyl bromide, or aromatic rings were designed and synthesized. The minimum inhibitory concentration (MIC) of the compounds against P. aeruginosa was assayed and the biofilm inhibition ratio was determined at different concentrations lower than the MIC. C-5 aromatic substituted furanones showed remarkable biofilm formation as well as inhibition of virulence factor production in P. aeruginosa. Fluorescence report analysis identified the QS regulatory mechanism of the most active compound 29. This study provides us a novel candidate for combating drug resistant bacteria strains by merely inhibiting biofilm formation. Without suppressing the regular life cycle of the bacteria, bacterial resistance mechanisms may not be activated. Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract: Reaction of α,β-ethylenic and acetylenic phosphonic acid monoesters with (biscollidine)iodine(I) or (biscollidine)bromine(I) hexafluorophosphate led to α,β-unsaturated halides by, without precedent, dephosphorylation reactions. [Copyright &y& Elsevier]