118-79-6Relevant articles and documents
Bromination of Phenols by Use of Benzyltrimethylammonium Tribromide
Kajigaeshi, Shoji,Kakinami, Takaaki,Tokiyama, Hajime,Hirakawa, Takahiro,Okamoto, Tsuyoshi
, p. 627 - 630 (1987)
The reaction of phenols with benzyltrimethylammonium tribromide in dichloromethane-methanol for 1 h at room temperature gave polybromophenols in good yields.
Kinetics and mechanism of oxidation of aspirin by bromamine-T, N-bromosuccinimide, and N-bromophthalimide
Ramachandrappa,Puttaswamy,Mayanna,Made Gowda
, p. 407 - 414 (1998)
The kinetics of the oxidation of aspirin (ASP) by bromamine-T (BAT), N-bromo-succinimide (NBS), and N-bromophthalimide (NBP) has been studied in aqueous perchloric acid at 303 K. The oxidation reaction follows identical kinetics with first-order in [oxidant], fractional-order in [ASP], and inverse fractional-order in [H+]. Under identical experimental conditions the extent of oxidation with different oxidizing agents is in the order: NBS > BAT > NBP, The rate decreased with decreasing dielectric constant of the medium. The variation of ionic strength and the addition of the reaction products and halide ions had no significant effect on the reaction rate. The solvent isotope effect was studied using D2O. Kinetic parameters were evaluated by studying the reaction at different temperatures. The reaction products were identified by GC-MS. The proposed reaction mechanism and the derived rate law are consistent with the observed kinetic data. Formation and decomposition constants for ASP-oxidant complexes have been evaluated. Decarboxylation, bromination, and loss of acetic acid gave 2,4,6-tribromophenol.
Electrophilic bromination in flow: A safe and sustainable alternative to the use of molecular bromine in batch
Van Kerrebroeck, Reinout,Naert, Pieter,Heugebaert, Thomas S.A.,D’hooghe, Matthias,Stevens, Christian V.
, (2019)
Bromination reactions are crucial in today’s chemical industry since the versatility of the formed organobromides makes them suitable building blocks for numerous syntheses. However, the use of the toxic and highly reactive molecular bromine (Br2) makes these brominations very challenging and hazardous. We describe here a safe and straightforward protocol for bromination in continuous flow. The hazardous Br2 or KOBr is generated in situ by reacting an oxidant (NaOCl) with HBr or KBr, respectively, which is directly coupled to the bromination reaction and a quench of residual bromine. This protocol was demonstrated by polybrominating both alkenes and aromatic substrates in a wide variety of solvents, with yields ranging from 78% to 99%. The protocol can easily be adapted for the bromination of other substrates in an academic and industrial environment.
Enthalpies of formation of 2,4,6-tribromophenol and of 2,4,6-tribromoaniline
Allot, Philip H.,Finch, Arthur,Pilcher, Geoffrey,Nunez, Lisardo,Barral, Luis
, p. 771 - 780 (1987)
The standard (p0 = 101.325 kPa) molar enthalpies of formation at 298.15 K of crystalline 2,4,6-tribromophenol and of 2,4,6-tribromoaniline were determined by both solution-reaction calorimetry and by rotating-bomb calorimetry.The values from the two methods agreed to within the limits of experimental error.The standard molar enthalpies of sublimation at 298.15 K were measured by microcalorimetry. 2,4,6-Tribromophenol: ΔfH0m(cr) = -98.5+/-2.3 kJ*mol-1, ΔgcrH0m = 97.6+/-1.1 kJ*mol-1; 2,4,6-tribromoaniline: ΔfH0m(cr) = 57.9+/-2.4 kJ*mol-1, ΔgcrH0m = 101.1+/-1.1 kJ*mol-1.The derived standard molar enthalpies of formation of the gaseous compounds were compared with values estimated assuming that each group, when substituted into the benzene ring, produces a characteristic increment in the enthalpy of formation.
Studies directed toward total synthesis of rhodocomatulins: A regioselective synthesis of brominated hydroxyanthraquinones by anionic annulations
Sk, Md Raja,Chakraborty, Soumen,Mal, Dipakranjan
, p. 309 - 317 (2018)
In this work, brominated hydroxyanthraquinones, which are the core structural motif of naturally occurring bromorhodocomatulins, were successfully synthesized using Hauser annulation reaction as the key step. When brominated Michael acceptors (brominated p-quinone monoketals) and cyanophthalides or bromocyanophthalides (Hauser donors) were reacted under the annulation conditions, brominated anthraquinones were obtained with 81–87% yields for four examples. On acidic quenching, products were obtained as solid which were separated by filtration and purified by recrystallization in acetone. No chromatography was required.
Benzylic oxidation by the GIF(IV) system
Barton,Halley,Ozbalik,Mehl
, p. 6615 - 6618 (1989)
Oxidation of ethylbenzene, diphenylmethane and benzylcyclopropane affords, in each case, the corresponding ketone as unique product. There is no detectable attack on the aromatic rings and only traces of phenol are formed from benzene. The oxidation of cumene affords acetophenone and 2-phenyl-2-hydroxypropane in nearly the same proportions as in a Gif(IV) oxidation of cumene hydroperoxide. An explanation is given.
Oxidovanadium (V and IV) complexes incorporating coumarin based O^N^O ligand: Synthesis, structure and catalytic activities
Majumder, Mitali,Krishna Rajak, Kajal
, (2020)
The tridentate ligand H2L1, [(E)-7-Hydroxy-8-[(2-hydroxy-phenylimino)-methyl]-4-methyl-chromen-2-one] has been used in the present work towards the synthesis of mononuclear oxidovanadium complexes. Three mononuclear complexes [VOL1(OMe)(MeOH)], 1; [VO(L1)(8-Hq)], 2 and [VO(L1)(1,10-phen)], 3 have been successfully synthesized with high yields by reacting [VO(acac)2] with H2L1 in 1:1 ratio in methanol under refluxing conditions where 8-hydroxyquinoline and 1,10-phenanthroline were used as co-ligands in the synthesis of complex 2 and 3. X-ray crystallographic studies reveal that in all the complexes synthesized in the present study, the ligand H2L1 binds as O^N^O coordinating ligand. The synthesized complexes were well characterized by using UV–Vis, IR, NMR and Mass spectral techniques. The physiochemical properties have been well interpreted by density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations. The synthesized complexes were established to show some distinctive properties e.g. oxidative bromination of aromatic aldehyde with high conversion rate and enhanced selectivity as well as high TON and TOF. The above properties were all well matched and demonstrated by using UV–visible and fluorescence as well as quenching studies. Complex 1 reacts with 3,5-DTBC catalytically in presence of molecular oxygen to generate corresponding ortho-benzoquinone.
A scalable and green one-minute synthesis of substituted phenols
Elumalai, Vijayaragavan,Hansen, J?rn H.
, p. 40582 - 40587 (2020/11/18)
A mild, green and highly efficient protocol was developed for the synthesis of substituted phenols via ipso-hydroxylation of arylboronic acids in ethanol. The method utilizes the combination of aqueous hydrogen peroxide as the oxidant and H2O2/HBr as the reagent under unprecedentedly simple and convenient conditions. A wide range of arylboronic acids were smoothly transformed into substituted phenols in very good to excellent yields without chromatographic purification. The reaction is scalable up to at least 5 grams at room temperature with one-minute reaction time and can be combined in a one-pot sequence with bromination and Pd-catalyzed cross-coupling to generate more diverse, highly substituted phenols.
A convenient and efficient H2SO4-promoted regioselective monobromination of phenol derivatives using N-bromosuccinimide
Wu, Yong-Qi,Lu, Hai-Jia,Zhao, Wen-Ting,Zhao, Hong-Yi,Lin, Zi-Yun,Zhang, Dong-Feng,Huang, Hai-Hong
supporting information, p. 813 - 822 (2020/02/15)
A convenient, rapid H2SO4-promoted regioselective monobromination reaction with N-bromosuccinimide was developed. The desired para-monobrominated or ortho-monobrominated products of phenol derivatives were obtained in good to excellent yields with high selectivity. Regioselective chlorination and iodination were also achieved in the presence of H2SO4 using N-chlorosuccinimide and N-iodosuccinimide, respectively.
Crystal structure and catalytic properties of a vanadium complex cis-[VO2(Him-py)(im-py)]2·3H2O
Sun, Meng,Zhang, Shaowei,Zhang, Jie,Xia, Wen,Chen, Jialiang,Yu, Xianyong
, p. 1899 - 1909 (2019/06/04)
The coordination behavior of Him-py (2-(1H-imidazol-2-yl)pyridine) toward vanadium has been explored. The six-coordinate complex, cis-[VO2(Him-py)(im-py)]2·3H2O (1), was synthesized by the coordination reaction of NH4VO3 and Him-py in the aqueous methanol solution, which was characterized by single-crystal X-ray technology. It belongs to the monoclinic space group P21/n with a = 8.0756(6), b = 19.3531(15), c = 11.4433(8), β = 106.905(2), V = 1711.2(2), and Z = 2. The crystal structure shows that the six-coordinate vanadium is bonded to two cis-oxido ligands and two bidentate ligands, Him-py and im-py. Interestingly, when crystals of 1 were immersed in H2O2, a peroxovanadium compound, (H2im-py)[OV(O2)2(Him-py)] (2), was obtained, which crystallizes in the orthorhombic space group Fdd2 with a = 22.600(2), b = 22.7259(13), c = 18.0146(11), V = 9252.4(12), and Z = 16, and consists of a seven-coordinate peroxovanadate(V) ion, one Him-py and one H2im-py ligand. Moreover, we also studied the catalytic activity of 1 in the oxidative bromination of phenol/aniline-like compounds towards mimicking bromoperoxidase reactivity.
