Ammonium Tribromide Research Articles

Tribromide enabled step-up generation of spirolactams from esters employing oxidative dearomatization of arenols.

Synthetically challenging spirolactams were developed in good yields and regio-selectivity through a step-up oxidative dearomatization of easily accessible arenols tethered to esters in the presence of quaternary ammonium tribromide as an economic oxidant and amines. The reaction mechanism associated with this unprecedented dearomative lactamisation has been forecasted with a series of controlled experiments and DFT studies.

A computational approach to understanding the mechanism of aromatic bromination using quaternary ammonium tribromides

Quaternary ammonium tribromides (QATBs) have garnered interest for nearly a century now. Various types of tribromides have been synthesized over the years and their diverse applications have been extensively reported. However, despite the fact that these reagents are touted as safer alternatives to the very poisonous bromine, there is insufficient information on the structure of Br3− in QATB systems and there is still no clear explanation for how the tribromide ion (Br3−) participates in bromination reactions. This paper reports a through structural assessment of Br3−, followed by an attempt was made to fully understand the mechanistic behaviour of tribromide during bromination of aromatic compounds.

Synthetic utility of biomimicking vanadium bromoperoxidase and n-tetrabutylammonium tribromide (TBATB) in organic synthesis.

Nature has established a broad spectrum of methods to introduce halogen atoms in organic compounds. Recent developments have revealed that haloperoxidases are one of the major sources responsible for incorporating bromines to produce bromoorganics in nature. Pioneering studies of numerous researchers have unravelled the details of haloperoxidases, mainly vanadium dependent enzyme bromo- and iodo-peroxidases, including reaction mechanism, kinetics and especially biomimicking studies. In this review, we initially have described the scope of biomimicking vanadium bromoperoxidase in producing the bromonium ion and its further utilisation in conducting oxidative bromination or cleavage of various organic molecules. Moreover, by biomicmicking, the synthesis of OATB and the synthetic utility of various organic ammonium tribromides (OATBs) have been discussed. Among such OATBs, n-tetrabutylammonium tribromide (TBATB) has been explored for bromination of organic molecules as well as in the facile removal of several protecting groups and as a potential catalyst in various synthetic transformations. This review attempts to compile a myriad of reactions concerning the catalytic activity of vanadium bromoperoxidases and the usefulness of various OATBs, particularly with special emphasis on TBATB in various organic transformations.

Visible photo-induced catalyst-free polymerization via in situ prepared dibromide

In situ bromination of vinyl monomers with tetra-n-butyl ammonium tribromide and irradiation of the corresponding dibromide upon exposure to visible-LED (λ = 400 nm) followed by C-Br bond photocleavage, successfully synthesis of polystyrene, polyacrylamide and the related random and block compolymers. GPC data revealed relatively low distributions in molecular weight for Dibromide-synthesized homo/copolymers, comparable with data obtained for ATRP, photo-ATRP and metal-free photo-ATRP.

Controlling Stereoselectivity in Tribromide Mediated Oxidative Dearomatisations – Synthesis of Selective Spirofurano‐naphthalones

A series of ammonium tribromides were screened for exploring the role of ammonium counterpart attached to tribromides on generation of stereoselective spiro‐furans via oxidative dearomatisation of naphthols. The proposition enlightens a suitable combination of the ammonium tribromide and solvent employed, deliver the best achieved diastereoselectivities. This in turn, has also envisioned the mechanistic aspects related to this category of reactions. The mentioned dearomative spiro‐furano naphthalones has also been successfully achieved on a large‐scale.

A theoretical and experimental study on the effect of cationic moiety of quaternary ammonium tribromides in bromination reactions

Attempt has been made to explain why different aliphatic quaternary ammonium tribromides (QATBs) show different levels of efficiency in bromination reactions. For this study, tetrabutyl ammonium tribromide (TBATB, [N(C4H9)4]Br3), and cetyl trimethyl ammonium tribromide (CTMATB, [N(CH3)3C16H33]Br3) were used as representative examples. UV–Vis Spectroscopic method was employed to measure the thermodynamic parameters of the reactions. Influence of quaternary ammonium cation on tribromide (Br3−) performance was assessed with the aid of Density Functional Theory (B3LYP/6-311++G(d,p)) by determining the dissociation energy of the QATBs, energies of pairs of their frontier orbitals, which are HOMO and LUMO and calculation of dipole moments.

The Interaction of Bovine Serum Albumin with Trimeric (Methyldodecylbis [2- (Dimethyldodecylammonio) Ethyl] Ammonium Tribromide and Make A Comparison with Corresponding Gemini and Monomeric Surfactants

The Interaction of Bovine Serum Albumin with Trimeric (Methyldodecylbis [2- (Dimethyldodecylammonio) Ethyl] Ammonium Tribromide and Make A Comparison with Corresponding Gemini and Monomeric Surfactants

Substrate Controlled Regioselective Bromination of Acylated Pyrroles Using Tetrabutylammonium Tribromide (TBABr3).

Electrophilic bromination of pyrroles bearing carbonyl substituents at C-2 typically results in a mixture of the 4- and 5-brominated species, generally favoring the 4-position. Herein, we describe a substrate-controlled regioselective bromination in which tetra-butyl ammonium tribromide (TBABr3) reacts with pyrrole-2-carboxamide substrates to yield the 5-brominated species as the predominant (up to >10:1) product.

O-Xylylene Bis(Triethyl Ammonium Tribromide) as a Mild and Recyclable Reagent for Rapid and Regioselective Bromination of Anilines and Phenols

o-Xylylene Bis(Triethyl Ammonium Tribromide) as a Mild and Recyclable Reagent for Rapid and Regioselective Bromination of Anilines and Phenols

Comparative study of 2,4,6-trichlorophenol adsorption by montmorillonites functionalized with surfactants differing in the number of head group and alkyl chain

Understanding the structures and characteristics of surfactants used to modify montmorillonites is crucial to predict the adsorption capacity of the resultant organo-montmorillonites in the aquatic environment. Herein, organo-montmorillonites modified by surfactants containing various amounts of head groups and hexadecyl chains were prepared. A general comparison was conducted of organo-montmorillonites modified by methyl hexadecyl bis[3-(dimethylhexadecylammonio)ethyl] ammonium tribromide (16-2-16-2-16), dimeric surfactants (1, 2-bis (hexadecyldimethylammonio) ethane dibromide, 16-2-16) and cetyl trimethyl ammonium bromide (CTAB) for their adsorption performance on 2,4,6-trichlorophenol (2,4,6-TCP) from aqueous solution. The resultant organo-montmorillonites were characterized by XRD, TGA and FT-IR spectroscopy. Batch studies were performed to evaluate the influences of various parameters like the amount of modifiers, the number of alkyl chain, contact time and solution pH on the removal of 2,4,6-TCP. Results indicated that the removal efficiency follows the order of CTAB-Mt <16-2-16-Mt<16-2-16-2-16-Mt from 0.4 CEC to 1.2 CEC, which may be due to increasing hydrophobicity with the increase in hexadecyl chain number. However, the adsorption capacity is on the rise in the order 16-2-16-Mt>16-2-16-2-16-Mt>CTAB-Mt beyond 1.2 CEC. This might be interpreted in terms of the combined contribution of packing density of hexadecyl chains in the interlayer of montmorillonites and ion–dipole interaction between the head group of intercalated surfactants and 2,4,6-TCP. Full kinetics, equilibrium and thermodynamics were also undertaken. Moreover, the maximum adsorption capacities of 2,4,6-TCP were 328.9mg/g at 1.6 CEC for CTAB-Mt and 306.7mg/g at 0.8 CEC for 16-2-16-Mt, respectively, whereas as high as 322.6mg/g for 16-2-16-2-16-Mt even at the modifier amount as low as 0.6 CEC. This study suggests that 16-2-16-2-16-Mt with three head groups and hexadecyl chains can serve as a more high-efficiency and cost-effective adsorbent for removal of 2,4,6-TCP from aqueous solution.

Oxidative Syntheses and Ring Opening of Oxazolines and Related Compounds by Ammonium Tribromide

Oxidative Syntheses and Ring Opening of Oxazolines and Related Compounds by Ammonium Tribromide

“A Jack of Trio”-robust one-pot metal free oxidative amination, azidation and peroxidation of phenols

Facile generation of quaternary carbon centres has been realised in the presence of phenyl trimethyl ammonium tribromide (PTAB) mediated oxidative dearomatisation.

A comparison of trimeric surfactant intercalated montmorillonite with its gemini modified one: Characterization and application in methyl orange removal

Trimeric surfactant methyldodecylbis [2-(dimethyldodecylammonio)ethyl] ammonium tribromide (3RenQ) and the corresponding dimer 1.2-bis(dodecyldimethylammonio)ethane dibromide (2RenQ), were used to modify sodium montmorillonite. Organo-montmorillonites 3RenQ-Mt and 2RenQ-Mt were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, N2 adsorption isotherms, thermogravimetric analysis (TG), scanning electron microscopy (SEM) and dispersibility measurement. The results showed that 3RenQ and 2RenQ had inserted into the lamella of sodium montmorillonite successfully, the interlayer spacer and the hydrophilicity of organoclays increased with the increasing of the cationic exchange capacity (CEC) of surfactants and polymerization degree. The adsorption experiments of methyl orange (MO) on 3RenQ-Mt and 2RenQ-Mt were studied using batch method as a function of the concentration of surfactants, contact time, pH and temperature. The optimal conditions for MO on 3RenQ-Mt and 2RenQ-Mt were as follows: 1.0 CEC of the concentration of surfactants, contact time of 6h, natural pH of 3, the temperature of 20°C, the equilibrium adsorption capacity of 3RenQ-Mt and 2RenQ-Mt reached to 85.97 and 98.07mgg−1, respectively; at the same experimental condition, 3RenQ-Mt exhibited the stronger interaction with MO than 2RenQ-Mt. The kinetic data were better described by the pseudo-second order kinetics model. The adsorption isotherm was in good agreement with the Langmuir model. Thermodynamic parameters such as the Gibbs free energy ΔGθ, the standard enthalpy ΔHθ and the standard entropy ΔSθ confirmed that the process of MO adsorption was spontaneous, exothermic, physisorption and randomness decreasing.

Development of a new class of brominated polymeric flame retardants based on copolymers of styrene and polybutadiene

Brominated polymeric flame retardants (FR) have been developed that can provide effective flame retardant performance in polymer systems that previously relied on hexabromocyclododecane (HBCD). This polymeric FR material exhibits a superior environmental profile to that of HBCD and other lower molecular weight FR molecules. The brominated polymer flame retardant is based on a copolymer of styrene and butadiene where the polybutadiene portion is brominated on the 1,2 and 1,4 isomer units to give a brominated polybutadiene. Bromination is best carried out with a quaternary ammonium tribromide reagent which provides a selective bromination of just the polybutadiene portion of the copolymer. A styrene-butadiene-styrene (SBS) triblock architecture is utilized where the presence of the styrene enhances the thermal stability and gives the copolymer to better compatibility when blended with polystyrene. The resulting brominated polybutadiene-polystyrene (BrPBPS) polymeric flame retardant contains similar aliphatic bromine as in HBCD but with a higher molecular weight structure. BrPBPS provides similar flame retardant activity as HBCD in polystyrene blends where both release HBr to provide gas phase activity. Both also provide enhanced polymer degradation as another major pathway for condensed FR activity.

Tribromide ion immobilized on magnetic nanoparticles as an efficient catalyst for the rapid and chemoselective oxidation of sulfides to sulfoxides

GRAPHICAL ABSTRACT

Phenyl trimethyl ammonium tribromide mediated robust one-pot synthesis of spiro-oxacycles - an economic route - stereoselective synthesis of oxaspirohexacyclodieneones.

This paper entails the first recognition of Phenyl Trimethyl Ammonium Tribromide (PTAB) as an effective reagent for spiro-cyclizations proceeding via oxidative dearomatization. The experiment exhibits economical, metal and ligand free one-pot accomplishment of these significant transformations. The described protocol presents the first generalised methodology of spiro-oxacycle synthesis which can be applied towards various directions. A stereoselective synthesis of oxa-spirocyclooxadieneones has been accomplished.

Novel Metal- and Mineral-Acid–Free Synthesis of Organic Ammonium Tribromides and Application of Ethylenephenanthrolium Bistribromide for Bromination of Active Methylene Group of 1,3-Diketones and β-Ketoesters

A novel procedure for the preparation of organic ammonium tribromides (OATBs) is described from their corresponding bromides. Quaternary ammonium bromides (QABs) and a N,N′-heterocyclic dibromide are efficiently oxidized to their corresponding monotribromides and bistribromide by m-chloroperbenzoic acid (MCPBA) in the presence of 2 and 4 equiv of KBr, respectively. The reactions are carried out in an aqueous medium without the use of any mineral acid or metal catalyst/promoters. A variety of tribromides are synthesized in very good yields including a hitherto unknown reagent, 1,10-(ethane-1, 2-diyl)phenanthrolinediium bistribromide (EPDBT). EPDBT is investigated as brominating agent and found to be highly effective for selective bromination of active methylene groups of a variety of 1,3-diketones and β-ketoesters.

Novel Protocol for the Synthesis of Organic Ammonium Tribromides and Investigation of 1,1′-(Ethane-1,2-diyl)dipiperidinium Bis(tribromide) in the Silylation of Alcohols and Thiols

Abstract A novel and efficient protocol for the synthesis of organic ammonium tribromides (OATBs) is developed by using inexpensive and eco-friendly periodic acid as an oxidant for the conversion of Br− to Br3−. The method does not use any mineral acid and metal oxidants. The protocol is utilized to synthesize a new bis(tribromide) viz., 1,1′-(ethane-1,2-diyl)dipiperidinium bis(tribromide) (EDPBT). EDPBT is investigated as a catalyst in the silylation of alcohols and thiols by HMDS (hexamethyldisilazane) under solvent-free conditions.

Sodium Hypochlorite-promoted Novel Synthesis of Organic Ammonium Tribromides and Application of Phenanthroline Hydrotribromide in Chemoselective Oxidation of Organic Sulfides by Hydrogen Peroxide

Abstract A novel method of synthesis of organic ammonium tribromides (OATBs) is developed by using an inexpensive and eco-friendly sodium hypochlorite as oxidant for conversion of Br− to Br3−. The OATBs thus prepared include both quaternary ammonium tribromides and N-heterocyclic tribromides. A new addition to the family of OATBs is made in the form of phenanthroline hydrotribromide. The efficacy of this new tribromide as catalyst is ascertained in the oxidative transformation of organic sulfides to their corresponding sulfoxides and sulfones by hydrogen peroxide.

One pot Aziridation of 2,3-trans Stilbene with Chloramine T derivatives in the presence of catalyst phenyltrimethyl Ammonium Tribromide

Phenyltrimethyl ammonium tribromide is an excellent source of bromine which was found to be an efficient catalyst for aziridination of 2,3-trans stilbene utilizing Chloramine T derivatives as a practical nitrogen source. Chloramine T derivatives were examined and were found to give the corresponding trans-2,3-diphenyl-N-arylsulfonyl aziridines in good yields.DOI: http://dx.doi.org/10.3126/jncs.v29i0.9277 Journal of Nepal Chemical Society Vol. 29, 2012 Page: 121-125 Uploaded date: 12/6/2013