Synthesis of Bromoacetyl Derivatives by Use of Tetrabutylammonium Tribromide

Kajigaeshi, Shoji; Kakinami, Takaaki; Okamoto, Tetsuhiko; Fujisaki, Shizuo

doi:10.1246/bcsj.60.1159

Cited by 107 publications

(43 citation statements)

References 13 publications

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“…In the nitrothiophene series, the substrate 2-bromo-1-(5-nitrothiophen-2-yl)ethanone (2) was obtained from 1-(5-nitrothiophen-2-yl)ethanone (1), using a quaternary ammonium salt, tetrabutylammonium tribromide (TBABr 3 ) as brominating reagent [12] (Scheme 1). In the nitrobenzene series, the substrate 2-bromo-1-(4-nitrophenyl)ethanone (3) is commercially available.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of α,β-Unsaturated Ketones as Chalcone Analogues via a SRN1 Mechanism

2007

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An electron-transfer chain reaction between 2-nitropropane anion and α-bromoketones derived from nitrobenzene and nitrothiophene was demonstrated by mechanistic study and a specific convenient synthetic protocol. Thus, 2-bromo-1-(5-nitrothiophen-2-yl)ethanone or 2-bromo-1-(4-nitrophenyl)ethanone were reacted with several cyclic nitronate anions to form α,β-unsaturated ketones via a S RN 1 mechanism. This new method can be used to synthesize a wide variety of chalcone analogues.

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Section: Resultsmentioning

confidence: 99%

Synthesis of α,β-Unsaturated Ketones as Chalcone Analogues via a SRN1 Mechanism

2007

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“…The oxidant TBATB was prepared by a reported method [13] and the solutions were prepared in 50% (v/v) acetic acid. The standardization of TBATB was carried out both iodometrically and spectrophotometrically.…”

Section: Methodsmentioning

confidence: 99%

Kinetics and mechanism of vanadium(IV) oxidation by tetrabutylammonium tribromide

Kalantre

Maradur

Gokavi

2007

Transition Met Chem

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The reaction between tetrabutylammonium tribromide(TBATB) and vanadium(IV) has been studied in 50% (v/v) acetic acid under second order conditions. The overall order of reaction is found to be two, unity in each reactant. The reaction involves two single-electron transfer steps generating bromine free radical in the first rate determining step. The test for the formation of free radicals in presence of added acrylonitrile was negative while added toluene increases the rate of the reaction considerably due to its conversion into benzyl bromide. The reaction is retarded by hydrogen ions as a result of protonation prior equilibria of the active reductant, vanadyl acetate. The oxidation of the vanadylsalen complex by TBATB proceeds more rapidly than that of vanadyl acetate but follows the similar kinetic behaviour. Considerable decrease in the entropy of activation of the reaction indicates formation of an ordered transition state between the two reactants and since the kinetic behaviour remains unaltered, even after the change in the ligand attached to the reductant, indicates an interaction between the reactants through the oxygen atom on the vanadyl ion.

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“…All starting materials and solvents were obtained from commercial suppliers and used as obtained. Compounds 2a [43], 2b [44], 2c [45], 2d [46], 2e [47], and 2f [48] were prepared according to the published procedures. Microwave synthesis: WBFY-201 apparatus.…”

Section: Experimental Partmentioning

confidence: 99%

Novel Disubstituted Phenylene‐Linked Bis‐imidazole Derivatives: Facile Synthesis and Optical Properties

Song

Zhu

Chen

et al. 2010

Helvetica Chimica Acta

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Six novel disubstituted phenylene-linked bis-imidazole derivatives, 3a -3f, were prepared by a onepot, microwave-assisted method under solvent-free conditions, in yields ranging from 61.6 to 85.6%. The new compounds were characterized by 1 H-and 13 C-NMR, UV/VIS, and fluorescence spectroscopy, and mass spectrometry, as well as by elemental analyses. The influence of substituents and solvents on the optical properties of 3a -3f was investigated. It was found that there is little influence on absorption and excitation spectra in contrast to emission spectra. Compounds 3a -3f exhibit strong fluorescence in solution, their fluorescence quantum yields ranging from 0.27 to 0.96. [14 -18]. Among these molecular fluorophores, phenylene-linked bis-imidazole derivatives have been used due to their unique optical properties [19 -21]. In addition, they can be used in two-photon fluorescence and as pH probe [22] [23]. To the best of our knowledge, several reports on the synthesis and on the physical properties of tetrasubstituted phenylene-linked bis-imidazole compounds have been published [24 -29], and the synthesis of phenylene-linked bis-imidazole compounds was only accomplished by condensation of 1,2-dicarbonyl compounds and aldehydes with NH 3 . However, to our surprise, studies on the synthesis and optical properties of disubstituted phenylene-linked bis-imidazole compounds were limited. In 1975, Mahadik and Sunthankar [30] reported the synthesis of some N,N'-disubstituted phenylene-linked bis-imidazoles with yields of 50 -60%. Since then, there were no reports on these compounds, except for the one of Jadhav and co-workers [24] in 2008, who described the synthesis of 2,2'-(1,4-phenylene)bis[5-phenyl-1H-imidazole] only, without giving any optical properties. Considering the above reports, the synthesis of novel disubstituted phenylene-linked bis-imidazoles and the study of the underlying structure -property relationships was a challenge.In this article, a microwave-assisted and solvent-free method for the synthesis of 5-aryl-substituted phenylene-linked bis-imidazoles is reported, involving condensation of benzene-1,4-dicarboximidamidium dichloride with 1-aryl-2-bromoethanones in the presence of using KHCO 3 as acid-binding agent. The six novel disubstituted phenylenelinked bis-imidazole derivatives 3a -3f were synthesized, characterized, and their optical properties investigated.

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Synthesis of Bromoacetyl Derivatives by Use of Tetrabutylammonium Tribromide

Abstract: Orange crystalline tetrabutylammonium tribromide was prepared using a simple method. The reaction of acetyl derivatives with an equimolar amount of the tribromide in dichloromethane–methanol at room temperature gave bromoacetyl derivatives in fairly good yields.

Cited by 107 publications

References 13 publications

Synthesis of α,β-Unsaturated Ketones as Chalcone Analogues via a SRN1 Mechanism

Synthesis of α,β-Unsaturated Ketones as Chalcone Analogues via a SRN1 Mechanism

Kinetics and mechanism of vanadium(IV) oxidation by tetrabutylammonium tribromide

Novel Disubstituted Phenylene‐Linked Bis‐imidazole Derivatives: Facile Synthesis and Optical Properties

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