Electrocatalytic treatment of waste: studies on discoloration of an industrial azo dye effluent

A textile dye effluent containing chiefly reactive azo dyes has been treated electrochemically for discoloration and COD (chemical oxygen demand) reduction at different current densities, flow rates and dilution. Experiments have been carried out in a thin electrochemical reactor under single pass conditions using a dimensionally stable catalytic anode (DSA) and a stainless steel cathode.     

H-β-zeolite catalyzed synthesis of β-bromostyrenes from styrene bromohydrins

Synthesis of β-bromostyrenes from styrene bromohydrins using H-β-zeolite as catalyst under moderate conditions is reported. The catalyst could be regenerated and reused up to three consecutive cycles.     

Oxidative Esterification of Benzaldehyde and Deactivated Aromatic Aldehydes with N-Bromosuccinimide-pyridine

Whereas the oxidative esterification of benzaldehyde to methyl benzoate with N-bromosuccinimide (NBS)-pyridine requires dark conditions and 5 equivalents each of NBS and K₂CO₃ and gave only moderate yield (52%) of the product (McDonald et al. J. Org. Chem. 1989, 54, 1213), simple change of base to pyridine gave the desired product in 83% gas chromatographic yield with only 1 equivalent each of NBS and pyridine. Moreover, the reaction could be conducted without exclusion of light. Aromatic aldehydes bearing electron-withdrawing substituents at meta/para position yielded the corresponding methyl esters in still better yields.

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Water mediated deprotective intramolecular hydroamination of N-propargylaminopyridines: synthesis of imidazo[1,2-a]pyridines

Metal-free synthesis of substituted imidazole [1,2-a]pyridines from deprotective N-(prop-2-yn-1-yl)pyridin-2-amines in water is elucidated. Electron releasing substituents on pyridine ring provided pure products in quantitative yields without separation by column chromatography.     

KHSO4: a highly efficient and reusable heterogeneous catalyst for hydroarylation of styrenes

Abstract  

Hydroarylation of styrenes with arenes/heteroarenes using KHSO₄ (10 mol%) as an efficient heterogeneous catalyst is described. High conversion and selectivity (>99%) were observed for hydroarylation of styrenes with 2-naphthol at reflux temperature of 1,2-dichloroethane. Yields were quantitative with all styrenes. Moderate to good conversions and selectivities were achieved with other aromatics and heteroaromatics under the same conditions. Regeneration and reusability of KHSO₄ were demonstrated. Addition of a trace amount of water could help to reactivate the KHSO₄ through dispersion and to facilitate the hydroarylation reaction.     

Facile one-pot synthesis of α-bromoketones from olefins using bromide/bromate couple as a nonhazardous brominating agent

A new method for the preparation of α-bromoketones from olefins using bromide/bromate couple as a nonhazardous brominating agent has been developed. Several α-bromoketones were successfully prepared from a variety of olefins by this method. This procedure is an alternative to conventional molecular bromine.     

Investigations into the nitric acid mediated dehalonitration of halophenols

A reaction of nitric acid with bromophenols and iodophenols results in substitution of the halogen with a nitro group. The study indicates moderate reactivity for bromophenols and iodophenols, while chlorophenols were found to be sluggish in this reaction.     

Reductive dehalogenation of halophenols in sulfite-bisulfate medium

The KHSO₄-Na₂SO₃ system is found to be simple and inexpensive for reductive elimination of halogens (Br, I) from the corresponding halophenols under reflux conditions in dry methanol. Under similar conditions the reaction is sluggish with chlorophenols.     

N‐Bromosuccinimide: A Facile Reagent for the Oxidation of Benzylic Alcohols to Aldehydes

The oxidation of benzylic alcohols to aldehydes using N‐bromosuccinimide (NBS) under ambient conditions without use of a transition‐metal catalyst has been described.     

I−/IO3 − Assemblies as Promoters of Iodohydrin Formation

Abstract

The direct conversion of olefins to their corresponding iodohydrins is efficient with I^?/IO₃ ^? assemblies in an aqueous acidic medium. Iodohydrins were obtained in moderately good yields at ambient reaction conditions without employing any metal catalysts. The addition of IOH across the olefin follows the Morkovnikov's rule.