Aqueous Phase Bromination by Micellar Solution of Sodium Dodecyl Sulfate (SDS): An Undergraduate Chemistry Experiment

Background: Bromination is a key reaction in chemical industry, since the organobromines find application in diverse fields like pharmaceuticals, dyes, fire retardants and as intermediates in chemical synthesis. Objective: To carry out green, in-situ bromination of acetanilide in aqueous medium using micellar SDS as catalyst. Methods: Bromination of acetanilide in-situ using potassium bromide as a non-corrosive source of bromine, ceric ammonium nitrate as oxidant, micellar solution of sodium dodecyl sulphate (SDS) as catalyst and water as solvent. Results: p-Bromoacetanilide was prepared in excellent yields, at room temperature, using green chemistry principles. Conclusion: The presented method provides a fast and environmentally safe route for the preparation of p-bromoacetanilide from acetanilide. It avoids the use of volatile, corrosive, and hazardous substances like liquid bromine and acetic acid. The use of water makes it safer and free from hazardous organic solvents. This reaction can be suitably adopted at the undergraduate level and may find use in the synthesis of commercially important bromo compounds.

Dehydration of isopropyl alcohol with activated carbon functionalized with Br- and S-containing reagents

Bromination of activated carbon GSGD was performed and active bromine-containing precursors were obtained, in which bromine is capable of being replaced by sulfur-containing functional groups. Bromination with liquid bromine and a solution of bromine in potassium bromide at room temperature leads to the introduction of 0.44–0.45 mmol g–1 of bromine into the surface layer of activated carbon. The treatment of brominated samples with sulfur-containing reagents with subsequent oxidation allows obtaining carbon samples that are catalytically active in the dehydration reaction of isopropyl alcohol in a gas phase. The temperature of complete conversion of isopropyl alcohol to propylene is a measure of catalytic activity. The concentration of sulfogroups in the prepared samples is up to 0.3 mol g–1. Thermogravimetry and thermoprogrammed desorption with mass spectrometric registration of products were used to study the thermal stability of modified activated carbon samples. The influence of the nature of brominating reagents, hydrolysis conditions and oxidation conditions on the structure, surface concentration of grafted S-containing groups and catalytic properties of the obtained materials was studied. Pre-bromination leads to an increase in the catalytic activity of activated carbon modified with sulfur-containing groups and the temperature of complete conversion of isopropyl alcohol to propylene decreases up to 400C depending on the concentration of sulfogroups.

Rapid Carbon Formation from Spontaneous Reaction of Ferrocene and Liquid Bromine at Ambient Conditions

Herein, we present an interesting route to carbon derived from ferrocene without pyrolysis. Specifically, the direct contact of the metallocene with liquid bromine at ambient conditions released rapidly and spontaneously carbon soot, the latter containing dense spheres, nanosheets, and hollow spheres. The derived carbon carried surface C-Br bonds that permitted postfunctionalization of the solid through nucleophilic substitution. For instance, treatment with diglycolamine led to covalent attachment of the amine onto the carbon surface, thus conferring aqueous dispersability to t he solid. The dispersed solid exhibited visible photoluminescence under UV irradiation as a result of surface passivation by the amine. Hence, the present method not only allowed a rapid and spontaneous carbon formation at ambient conditions, but also surface engineering of the particles to impart new properties (e.g., photoluminescence).

SYNTHESIS OF 2-[(3-SUBSTITUTEDIMINO)-1,2,4-DITHIAZOLO]AMINO-11-(PIPERAZIN-1-YL)DIBENZO [b,f][1,4]OXAZEPINES

<div><p><em>Recently in this laboratory a novel series of </em><em>2-[(3-substitutedimino)-1,2,4-dithiazolo]amino-11-(piperazin-1-yl)dibenzo [b,f][1,4]oxazepines</em><strong><em> [VIB(a-h)] </em></strong><em>was synthesized by the oxidative cyclisation of 2-[substituted-2,4-dithiobiureto]-11-(piperazin-1-yl) dibenzo [b,f] [1,4]oxazepines <strong>[VB(a-h)] </strong> in<strong> </strong>chloroform medium by making the use of liquid bromine as oxidizing agent. The products were characterized and justified on the basis of elemental analysis, chemical characteristics and spectral studies. </em></p></div>

New insights into bromination process: effective preparation of Ambroxol

Ambroxol used as an expectorant in treating respiratory diseases was effectively prepared with a total yield of 62 %, with o-toluidine as the feedstock via successive procedures of electrophilic bromination, acetylation, radical benzylic bromination, N-alkylation and hydrolysis processes. The addition of aqueous hydrogen peroxide could enhance the utilisation of liquid bromine in the electrophilic bromination of o-toluidine, avoiding the hazardous HBr generated as a by-product. In addition, liquid bromine promoted by MnO