5401-62-7Relevant academic research and scientific papers
TRANSFORMATION OF AN EPOXIDE INTO A 1,2-DIBROMOALKANE BY A DIOXODIBROMOMOLYBDENUM(VI) COMPLEX
Arzoumanian, Henri,Krentzien, Heinz,Lai, Richard,Metzger, Jacques,Petrignani, Jean-Francois
, p. 175 - 178 (1983)
Dioxodibromomolybdenum(VI) when complexed with acetonitrile reacts with cyclohexane oxide in a 2/1 ratio to give 1,2-dibromocyclohexane.This novel bromination reaction probably proceeds by an initial oxirane ring opening to give the β-bromoalkoxide, which then reacts with a second molecule of molybdenumdibromide to give the 1,2-dibromoalkane.
Comparison of Molecular Bromine and Tribromide Ion as Brominating Reagents. 1. Kinetic Evidence for Different Mechanisms of Addition to Cyclohexene.
Bellucci, Giuseppe,Bianchini, Roberto,Ambrosetti, Roberto,Ingrosso, Giovanni
, p. 3313 - 3318 (1985)
The kinetics of bromination of cyclohexane with molecular bromine and with tetrabutylammonium tribromide in a series of chlorinated hydrocarbons of dielectric constant ranging between 2.2 and 10.7 have been investigated with the stopped-flow technique.Third-order (second order in Br2) and second order (first-order in Br3-) rate laws were respectively followed by the bromine and the tribromide reactions.Only in the least polar solvent, carbon tetrachloride, the reaction of molecular bromine gave erratic results even when fitted to a two-term rate equation.The rates of the bromine and of the tribromide reactions exhibited opposite temperature coefficients, negative for the former and positive for the latter.Added tetrabutylammonium bromide had only a modest negative salt effect on the rate of the Br3- reaction, excluding its dissociation to free Br2 and reaction of this electrophile.The rate of the free Br2 reaction was substantially determined by the solvent polarity.A linear plot of ln k3 against the Kirkwood function of the dielectric constant, indicating a highly polarized transition state, was obtained for reactions carried out in mixtures of 1,2-dichloroethane and chloroform.An inverted trend was observed for the rates of the tribromide reaction in the same binary mixture of solvents, but no linear plot was obtained, and the rates measured in the series of solvents correlated with the stability constants of Br3- and with the ability of solvents to hydrogen bond bromide ions.The reaction of tribromide, but not that of molecular bromine, was subjected to a kinetic solvent isotope effect (kH/kD=1.175 (0.031)) in CHCl3/CDCl3.The results are consistent with an ionic mechanism involving the rate-determining formation of a bromonium-tribromide ion pair intermediate for the free Br2 addition.For the Br3- reaction they point to the formation of an olefin-Br2 1:1 charge-transfer complex in equilibrium with the olefin and Br3-, followed by a rate- and product-determining nucleophilic attack by bromide on the transient complex through a transition state more charge delocalized than the initial state.
g-C3N4/metal halide perovskite composites as photocatalysts for singlet oxygen generation processes for the preparation of various oxidized synthons
Corti, Marco,Chiara, Rossella,Romani, Lidia,Mannucci, Barbara,Malavasi, Lorenzo,Quadrelli, Paolo
, p. 2292 - 2298 (2021/04/12)
g-C3N4/metal halide perovskite composites were prepared and used for the first time as photocatalysts forin situ1O2generation to perform hetero Diels-Alder, ene and oxidation reactions with suitable dienes and alkenes. The standardized methodology was made applicable to a variety of olefinic substrates. The scope of the method is finely illustrated and the reactions afforded desymmetrized hydroxy-ketone derivatives, unsaturated ketones and epoxides. Some limitations were also observed, especially in the case of the alkene oxidations, and poor chemoselectivity was somewhere observed in this work which is the first application of MHP-based composites forin situ1O2generation. The experimental protocol can be used as a platform to further expand the knowledge and applicability of MHPs to organic reactions, since perovskites offer a rich variety of tuning strategies which may be explored to improve reaction yields and selectivities.
Crystal structure, characterization, Hirshfeld surface analysis and DFT studies of two [propane 3-bromo-1-(triphenyl phosphonium)] cations containing bromide (I) and tribromide (II) anions: The anion (II) as a new brominating agent for unsaturated compounds
Nokhbeh, Seyed Reza,Gholizadeh, Mostafa,Salimi, Alireza,Sparkes, Hazel A.
, p. 542 - 554 (2019/06/18)
In this study, propane 3-bromo-1- (triphenyl phosphonium) bromide, I, and propane 3-bromo-1- (triphenyl phosphonium) tribromide, II, (II as a new brominating agent) were synthesized and characterized by 1H NMR, 13C NMR, 31P NMR, FT-IR, spectroscopy, Thermogravimetric Analysis, Differential thermal analysis, Differential scanning calorimetry and single crystal X-ray analysis. Density functional theory calculations (energy, structural optimization and frequencies, Natural Bond Orbital, absorption energy and binding energy) were performed by using B3LYP/6-311 G++ (d, p) level of theory. Hirshfeld surface analysis and fingerprint plots were utilized to investigate the role of bromide and tribromide anions on the crystal packing structures of title compounds. The results revealed that the change of accompanying anionic moiety can affect the directional interactions of C-H?Br hydrogen bonds between anionic and cationic units in which the H?Br with a proportion of 53.8% and 40.9% have the major contribution in the stabilization of crystal structures of I and II, respectively. Furthermore, the thermal stability of new brominating agent II with tribromide anion was compared with compound I with bromide anion. Nontoxicity, short reaction time, thermal stability, simple working up and high yield are some of the advantages of these salts.
Catalytic Bromination of Alkyl sp3C-H Bonds with KBr/Air under Visible Light
Zhao, Mengdi,Lu, Wenjun
supporting information, p. 5264 - 5267 (2018/09/12)
Alkyl sp3C-H bonds of cycloalkanes and functional branch/linear alkanes have been successfully brominated with KBr using air or O2 as an oxidant at room temperature to 40 °C. The reactions are carried out in the presence of catalytic NaNO2 in 37% HCl (aq)/solvent under visible light, combining aerobic oxidations and photochemical radical processes. For various alkane substrates, CF3CH2OH, CHCl3, or CH2Cl2 is employed as an organic solvent, respectively, to enhance the efficiency of bromination.
Dehalogenation of vicinal dihalo compounds by 1,1′-bis(trimethylsilyl)-1: H,1′ H-4,4′-bipyridinylidene for giving alkenes and alkynes in a salt-free manner
Rej, Supriya,Pramanik, Suman,Tsurugi, Hayato,Mashima, Kazushi
supporting information, p. 13157 - 13160 (2017/12/26)
We report a transition metal-free dehalogenation of vicinal dihalo compounds by 1,1′-bis(trimethylsilyl)-1H,1′H-4,4′-bipyridinylidene (1) under mild conditions, in which trimethylsilyl halide and 4,4′-bipyridine were generated as byproducts. The synthetic protocol for this dehalogenation reaction was effective for a wide scope of dibromo compounds as substrates while keeping the various functional groups intact. Furthermore, the reduction of vicinal dichloro alkanes and vicinal dibromo alkenes also proceeded in a salt-free manner to afford the corresponding alkenes and alkynes.
Complexes of cis-dioxomolybdenum(VI) with a chiral tetradentate tripodal-like ligand system: Syntheses, structures and catalytic activities
Ghosh, Sabari,Kurapati, Sathish Kumar,Pal, Samudranil
, p. 26 - 33 (2017/03/07)
Racemic complexes with the general formula cis-[MoO2(bzacLn)] (1–4) (H2bzacLn?=?2-((4/5-R-2-hydroxyphenylamino)(pyridin-2-yl)methyl)-1-phenylbutane-1,3-dione, where n?=?1–4 for R?=?H, 5-Me, 5-Cl and 4-Me, respectively and 2Hs represent the dissociable phenolic proton and the active tertiary CH proton) have been synthesized in 75–82% yields by reacting [MoO2(bzac)2] (Hbzac?=?benzoylacetone) with the potentially N2O-donor 5,5-membered fused chelate rings forming Schiff bases 4/5-R-2-(2-pyridylaldimine)phenols (HLn; n?=?1–4 for R?=?H, 4-Me, 4-Cl and 5-Me, respectively) in hot methanol. The chiral ligand system (bzacLn)2?in 1–4 is formed via metal assisted Mannich-type addition of benzoylacetonate methine to the azomethine fragment of HLn. All four complexes have been characterized by elemental (CHN) analysis, solution conductivity, magnetic susceptibility, spectroscopic (IR, UV–Vis and NMR) and electrochemical measurements. The molecular structures of 1–3 have been established by single crystal X-ray crystallography. In each complex, the chiral (bzacLn)2?acts as a tetradentate, N2O2-donor, tripodal-like ligand system and along with the two mutually cis oxo groups forms a distorted octahedral N2O4coordination environment around the molybdenum(VI) center. All four complexes are diamagnetic and non-electrolytic. The infrared spectra are generally consistent with the structural formulas of 1–4. The electronic spectra of 1–4 in dimethylformamide display two strong absorption bands in the range 245–300?nm. The cyclic voltammograms of 1–4 in dimethylformamide exhibit a metal centered one-electron reduction response within ?0.64 to ?0.74?V. All these complexes (1–4) and the analogous cis-[MoO2(acacL1–4)] (5–8) synthesized from [MoO2(acac)2] (Hacac?=?acetylacetone) and HL1–4have been evaluated for their bromoperoxidase activities.
On the bromination of aromatics, alkenes and alkynes using alkylammonium bromide: Towards the mimic of bromoperoxidases reactivity
Mendoza, Fabian,Ruíz-Guerrero, Rosario,Hernández-Fuentes, Carlos,Molina, Paulina,Norzagaray-Campos, Mariano,Reguera, Edilso
supporting information, p. 5644 - 5648 (2016/11/28)
This article describes an efficient method of bromination of organic substrates including aromatics, alkenes and alkynes with NH4VO3as a catalyst and H2O2as an oxidant agent using a non-toxic and easy-to-handle source of bromine, tetrabutylammonium bromide. The process was developed under mild reaction conditions and is an innovation from reported methods in aspects such as: i) short reaction times, ii) the ability to work at room temperature, iii) regioselectivity and good yields.
Accessing Pincer Bis(carbene) Ni(IV) Complexes from Ni(II) via Halogen and Halogen Surrogates
Martinez, Gabriel Espinosa,Ocampo, Cristian,Park, Yun Ji,Fout, Alison R.
supporting information, p. 4290 - 4293 (2016/05/10)
This communication describes the two-electron oxidation of (DIPPCCC)NiX (DIPPCCC = bis(diisopropylphenyl-benzimidazol-2-ylidene)phenyl); X = Cl or Br) with halogen and halogen surrogates to form (DIPPCCC)NiX3. These complexes represent a rare oxidation state of nickel, as well as an unprecedented reaction pathway to access these species through Br2 and halogen surrogate (benzyltrimethylammonium tribromide). The NiIV complexes have been characterized by a suite of spectroscopic techniques and can readily reduce to the NiII counterpart, allowing for cycling between the NiII/NiIV oxidation states.
Cis-Dioxomolybdenum(VI) complexes with unsymmetric linear tetradentate ligands: Syntheses, structures and bromoperoxidase activities
Kurapati, Sathish Kumar,Pal, Samudranil
, p. 116 - 124 (2016/02/18)
Reactions of [MoO2(acetylacetonate)2], 2-((2-(2-hydroxyethylamino)ethylamino)methyl)-4-R-phenols (H2Ln, n = 1-5 for R = H, Me, OMe, Cl and Br, respectively) and KOH in 1:1:2 mole ratio in methanol afford a series of complexes having the general formula cis-[MoO2(Ln)] (1, 2, 3, 4, 5) in 81-86% yields. The complexes have been characterized using elemental analysis, spectroscopy (infrared, UV-visible, and 1H NMR, 13C NMR and 13C-DEPT NMR) and electrochemical measurements. The molecular structures of 1, 2, 3, 4 have been determined using single-crystal X-ray crystallography. In each of 1, 2, 3, 4, the ONNO-donor 6,5,5-membered fused chelate rings forming (Ln)2- and the two mutually cis oxo groups assemble a distorted octahedral N2O4 coordination sphere around the metal centre. In the crystal lattice, each of 1, 2, 3, 4 forms a one-dimensional infinite chain structure via intermolecular N-H...O hydrogen bonding interactions. In cyclic voltammograms, the diamagnetic complexes display an irreversible metal-centred reduction in the potential range -0.73 to -0.88 V (vs Ag/AgCl). The physicochemical data are consistent with a very similar gross molecular structure for all of 1, 2, 3, 4, 5. All the complexes exhibit decent bromoperoxidase activities and are also able to effectively catalyse benzoin and methyl(phenyl)sulfide oxidation reactions.
