16536-57-5Relevant academic research and scientific papers
Use of Organic Molecules as Mechanistic Probes for Semiconductor-Mediated Photoelectrochemical Oxidations: Bromide Oxidation
Fox, Marye Anne,Pettit, Thomas L.
, p. 5013 - 5015 (1985)
Cyclohexene has been used as an organic probe for mechanism in the semiconductor-photocatalyzed oxidation of bromide in acetonitrile.Products derived from bromine addition and from cyclohexenyl radical mediated autoxidation were isolated.These results implicate a mechanism in which the photoexcited semiconductor effects a one electron oxidation of adsorbed bromide, producing surface-bound bromine atoms.These potentially could abstract hydrogen from cyclohexene to initiate autoxidation or could migrate along the semiconductor surface, producing bromine (Br2), which migrates into solution where it is rapidly trapped in conventional electrophilic addition.
An efficient regioselective halogenation of 5-amino-endo-tricyclo[5.2.1.02,6]deca-4,8-dien-3-ones
Ramesh, Namakkal G,Heijne, Erik H,Klunder, Antonius J.H,Zwanenburg, Binne
, p. 1361 - 1368 (2002)
An effective regioselective halogenation of 5-amino-endo-tricyclo decenyl enaminones 6 using N-halosuccinimides is reported. The reaction is extremely fast and the yields are almost quantitative. Exclusive α,N-dihalo or α,γ-dihalo compounds can be obtaine
Dendrimeric organochalcogen catalysts for the activation of hydrogen peroxide: Origins of the "dendrimer effect" with catalysts terminating in phenylseleno groups
Drake, Michael D.,Bright, Frank V.,Detty, Michael R.
, p. 12558 - 12566 (2003)
Several scenarios were evaluated to explain the large "dendrimer effect" observed in the bromination of cyclohexene with H2O 2 and NaBr catalyzed by the addition of Frechet-type dendrimers terminating in -O(CH2)3SePh groups. Although phenylseleninic acid was an efficient catalyst for the oxidation of NaBr with H2O2, first-order rate constants for the selenoxide elimination were too small to produce PhSeO2H at a rate sufficient to explain the rates of catalysis and no dendrimer effect was observed in the rates of selenoxide elimination. An induction period was observed using 1-SePh as a catalyst for the oxidation of Br- with H2O2. The addition of preformed selenoxide 1-Se(=O)Ph gave immediate catalysis with no induction period. However, rates of oxidation of the selenides with H 2O2 under homogeneous or biphasic conditions or with t-BuOOH under homogeneous conditions were too slow to account for the rates of catalysis, and no dendrimer effect was observed in the rates of oxidation. The primary oxidant for converting selenides to selenoxides was "Br+" produced initially by the uncatalyzed background reaction of H2O 2 with NaBr and then produced catalytically following formation of selenoxide groups. Autocatalysis is observed, and the rate of oxidation increases with the number of SePh groups. Autocatalysis is the source of the large dendrimer effect observed with the SePh series of catalysts.
Positive halogens from halides and hydrogen peroxide with organotellurium catalysts
Detty, Michael R.,Zhou, Feng,Friedman, Alan E.
, p. 313 - 318 (1996)
The oxidations of sodium bromide, sodium chloride, and sodium iodide to positive halogen with hydrogen peroxide in two-phase systems of dichloromethane and pH 6 phosphate buffer were catalyzed by organotellurium catalysts 1-3. The positive halogens were trapped by cyclohexene for bromine and chlorine to give mixtures of the 1,2-dihalocyclohexane (4) and 2-halocyclohexanol (5). For the bromination (4a)/hydrobromination (5a) of cyclohexene, unoptimized turnover numbers of 1010 mol of product per mole of catalyst for 1, 960 for 2, and 820 for 3 were measured with 4a/5a ratios of 55:45, 53:47, and 52:48, respectively. In cyclohexane, the turnover number for 1 was 150 and the 4a/5a ratio was 68:32. In the uncatalyzed process and in the reaction of aqueous bromine with cyclohexene, the 4a/5a ratio is 55:45 in dichloromethane and 67:33 in cyclohexane. The relative rates of catalysis for equimolar amounts of 1-3 were nearly identical to the relative second-order rate constants for oxidation of the organotellurium compounds with hydrogen peroxide, which suggests that oxidation of the catalyst is the rate-determining step of the process. Stopped-flow studies indicated a rapid reaction (k = 22.5 ± 0.3 M-1 s-1 for iodide and 13.9 ± 0.5 M-1 s-1 for bromide) between halide and oxidized 3 to regenerate catalyst 3. Relative rates of catalysis with 0.1 mol % of 1-3 (relative to cyclohexene) were 4.6 for 1, 2.0 for 2, 1.0 for 3, and 0.11 for the control reaction with no catalyst at 296.1 ± 0.1 K. Oxidation of chloride with hydrogen peroxide with 1 as a catalyst was much slower but the unoptimized turnover number was 100 with a 4b/5b ratio of 7:93 (10:90 in the uncatalyzed process) in a two-phase cylohexane/aqueous system. Oxidized 3 reacts rapidly with both sodium chloride and sodium bromide to give products from oxidative addition of halogen to the catalyst. Stronger Te-Cl bonds relative to Te-Br bonds slow down the release of the Te(II) state of the catalyst. Positive iodine from catalysis with 1 was trapped by 4-pentenoic acid to give iodomethyl lactone 6.
SURFACTANT CONTROL OF BROMINATION PRODUCTS
Bianchi, M. T.,Cerichelli, G.,Mancini, G.,Marinelli, F.
, p. 5205 - 5208 (1984)
The product distribution in the bromination of cyclohexene is almost completely controlled by the addition order of the reactants to the surfactant, the obtained bromohydrin being 99percent pure.Water seems to be present all around the micelles head groups.
Electrochemical bromofunctionalization of alkenes in a flow reactor
Seitz, Jakob,Wirth, Thomas
supporting information, p. 6892 - 6896 (2021/08/20)
The bromination of organic molecules has been extensively studied to date, yet there is still a demand for safe and sustainable methodologies. Hazardous reagents, selectivity, low atom economy and waste production are the most persisting problems of brominating reagents. The electrochemical oxidation of bromide to bromine is a viable strategy to reduce waste by avoiding chemical oxidants. Furthermore, thein situgeneration of reactive intermediates minimizes the risk of hazardous reagents. In this work, we investigate the electrochemical generation of bromine from hydrobromic acid in a flow electrochemical reactor. Various alkenes could be converted to their corresponding dibromides, bromohydrines, bromohydrin ethers and cyclized products in good to excellent yields.
Halofunctionalization of alkenes by vanadium chloroperoxidase from: Curvularia inaequalis
Dong, Jia Jia,Fernández-Fueyo, Elena,Li, Jingbo,Guo, Zheng,Renirie, Rokus,Wever, Ron,Hollmann, Frank
supporting information, p. 6207 - 6210 (2017/07/10)
The vanadium-dependent chloroperoxidase from Curvularia inaequalis is a stable and efficient biocatalyst for the hydroxyhalogenation of a broad range of alkenes into halohydrins. Up to 1 200 000 TON with 69 s-1 TOF were observed for the biocatalyst. A bienzymatic cascade to yield epoxides as reaction products is presented.
Catalytic Asymmetric Bromination of Unfunctionalized Olefins with H2O as a Nucleophile
Zhang, Xun,Li, Jing,Tian, Hua,Shi, Yian
, p. 11658 - 11663 (2015/08/18)
The dimeric cinchona alkaloid (DHQD)2PHAL is used to catalyze an effective asymmetric bromohydroxylation of unfunctionalized olefins with H2O as nucleophile an N-bromobenzamide as a bromine source. A variety of optically active bromohydrins are formed with up to 88%ee. PHAL's positive: An effective asymmetric bromohydroxylation of unfunctionalized olefins with H2O as nucleophile catalyzed by the dimeric cinchona alkaloid (DHQD)2PHAL (see scheme) is described. Optically active bromohydrins are obtained with up to 88%ee.
Bromine and iodine-cucurbit[6]uril complexes: Preparation and applications in synthetic organic chemistry
Reddy,Cavallini,Demets,Silva
supporting information, p. 2262 - 2264 (2014/06/09)
Iodine and bromine inclusion compounds were easily prepared by gas diffusion of the halogens using finely powdered CB[6]. A brown powder consisting of I2-CB[6]·4H2O and an orange one of (Br 2)4-CB[6]·10H2O were employed in several different reactions. I2-CB[6] can be used in catalytic reactions giving yields comparable to those reported in the literature. Br 2-CB[6] was effectively applied in electrophilic bromination of benzene and formation of bromohydrin. However, the radical substitution at cyclohexene could not be performed. Overall, based on these results, several applications can be envisioned for these complexes. This journal is the Partner Organisations 2014.
Synthesis of Di-, Tri-, and tetrasubstituted oxetanes by rhodium-catalyzed O-H insertion and C-C bond-forming cyclization
Davis, Owen A.,Bull, James A.
supporting information, p. 14230 - 14234 (2015/02/19)
Oxetanes offer exciting potential as structural motifs and intermediates in drug discovery and materials science. Here an efficient strategy for the synthesis of oxetane rings incorporating pendant functional groups is described. A wide variety of oxetane 2,2-dicarboxylates were accessed in high yields, including functionalized 3-/4-aryl-and alkyl-substituted oxetanes and fused oxetane bicycles. Enantioenriched alcohols provided enantioenriched oxetanes with complete retention of configuration. The oxetane products were further derivatized, while the ring was maintained intact, thus highlighting their potential as building blocks for medicinal chemistry.
