- Water mediated, environmentally friendly, step-wise, tandem & one-pot syntheses of 2-(1H-benzo[d]imidazole-2-yl)-N-arylbenzamides
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Water mediated and environmentally friendly, step-wise, tandem & one-pot syntheses of 2-(1H-benzo[d]imidazole-2-yl)-N-arylbenzamide derivatives have been developed by simply combining phthalic anhydride, anilines and phenylenediammonium dihydrogenphosphate. This reaction has an easy workup, provides excellent yields, and uses water as the solvent which is considered to be relatively environmentally benign.
- Reddy, Yervala Dathu,Ramana Reddy, Chittireddy Venkata,Dubey, Pramod Kumar
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p. 2974 - 2979
(2014/01/06)
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- Chemoselective acylation of amines in aqueous media
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Amines are efficiently acylated by both cyclic and acyclic anhydrides by dissolving them in an aqueous medium with the help of a surfactant, sodium dodecyl sulfate (SDS). Cyclic and acyclic anhydrides react with equal ease with an amine, and amines with various stereo-electronic factors react at the same rates with an anhydride. Chemoselective acylation of amines in the presence of phenols and thiols and of thiols in the presence of phenols has been achieved. No acidic or basic reagents are used during the reaction. No Chromatographic separation is required for isolation of the acylated products. Reactions in a neutral aqueous medium, easy isolation of products, and innocuous by-products make the present method a green chemical process. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Naik, Sarala,Bhattacharjya, Gitalee,Talukdar, Bandana,Patel, Bhisma K.
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p. 1254 - 1260
(2007/10/03)
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- The cyclisation of substituted phthalanilic acids in acetic acid solution. A kinetic study of substituted N-phenylphthalimide formation
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One novel and ten known substituted 3′- and 4′-phthalanilic acids have been prepared. These have been cyclised to two novel and nine known substituted N-phenylphthalimides by heating with glacial acetic acid. Both phthalanilic acids and imides have been characterised in detail and spectroscopic data are given. The kinetics of cyclisation for phthalanilic acids has been examined in detail, and it has emerged that a complex mechanism is operating. This initially involves a reversible, solvent assisted intramolecular nucleophilic attack by amide nitrogen on the carboxylic acid carbonyl. Clear evidence is seen for a long-lived intermediate as a precursor to imide formation. The observed kinetics are rationalised using a model of rapid pre-equilibration, followed by the slow breakdown of the intermediate to imide. Observed rate constants for pre-equilibration show a well behaved, linear Hammett plot (ρ = -1.1), whereas those for formation of imide do not.
- Perry, Christopher J.,Parveen, Zahida
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p. 512 - 521
(2007/10/03)
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- Spectrophotometric and Titrimetric Determination of Carboxylic Acid Anhydrides
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Two redox methods are described for the determination of carboxylic acid anhydrides involving reaction with either an excess of 4-aminophenol or a measured but excessive amount of sulfanilamide and photometric titration of N-acyl-4-aminophenol with 2-iodylbenzoate by measuring the absorbance of orange-red product at 444 nm or the residual amount of sulfanilamide is determined by titration with chloramine-T in the presence of acidified potassium bromide using methyl red as visual indicator.Mixtures of certain anhydrides have also been analyzed by the 2-iodylbenzoate method.The methods are rapid, precise, and accurate.No correlation is needed if carboxylic and mineral acids are also present.Carboxylic acid chlorides also react quantitatively.
- Verma, Krishna K.,Tyagi, Pramila
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p. 2157 - 2160
(2007/10/02)
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