- Development of an efficient ruthenium catalyzed synthetic process and mechanism for the facile conversion of benzothiazoles to orthanilic acids
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Ruthenium-Schiff base complex catalyzed efficient protocol has been developed for the synthesis of orthanilic acids from benzothiazoles in good to excellent yields using N-haloamines. Hexa-coordinated ruthenium complex with Schiff base and triphenylphosphine ligands has been prepared and its catalytic function was invented for the synthesis of orthanilic acids. The synthetic process utilizes our efficient method for the selective and preferential oxidation of thiazole ring of benzothiazoles using N-haloamines without effecting phenyl ring. The detailed catalytic, mechanistic and kinetic investigations have been made for the synthetic reactions. Solvent isotope studies have been made in H2O-D2O and the reactions were carried out at different temperatures. Under the identical set of conditions, the kinetics of catalyzed reactions has been compared with uncatalyzed reactions and found that the catalyzed reactions are 9-11 folds faster. The catalytic constants (KC) have been calculated for each N-haloamine at different temperatures and the values of activation parameters with respect to the catalyst have been evaluated. Spectroscopic evidence for the formation of 1:1 complex between N-haloamine and ruthenium has been obtained. The observed results have been explained by a plausible mechanism and the related rate law has been deduced.
- Jagadeesh,Karthikeyan,Nithya,Sandhya, Y. Sree,Reddy, S. Sudhaker,Reddy, P. Pradeep Kumar,Kumar, M. Vinod,Charan, K.T. Prabhu,Narender,Bhagat
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experimental part
p. 99 - 107
(2010/12/18)
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- A study on the sulfonation of aromatic amines with sulfuric acid under microwave irradiation
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The sulfonation of aromatic amines with high yields, simple operations and short reaction time has been studied under microwave irradiation in solvent-free conditions.
- Li, Hui-Zhang,Xiao, Li-Wei,Li, Hong-Ya,Wang, Kai-Fang,Li, Xu
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p. 493 - 494
(2007/10/03)
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- Effect of substituent in diazotized orthanilic acid on the azo coupling with 7-acetylamino-4-hydroxynaphthalene-2-sulfonic acid in citrate-phosphate buffers
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Effect of substituent in the para position with respect to the diazo group in diazotized orthanilic acid derivatives on the rate and selectivity of azo coupling with 7-acetylamino-4-hydroxynaphthalene-2-sulfonic acid was studied in citrate-phosphate buffers. The selectivity of azo coupling at the 3-position of the azo component almost does not depend on the nature of electron-donor substituent. Electron-acceptor groups considerably reduce the selectivity of formation of the 3-isomer. Previous conclusions, according to which the rate-determining stages are different depending on the site of azo coupling of diazotized orthanilic acid with 7-acetylamino-4-hydroxynaphthalene-2-sulfonic acid, were found to be also valid for some 5-substituted orthanilic acid derivatives. The rate-determining stage in the azo coupling at the 3-position can change upon introduction of strong electron-acceptor substituents capable of interacting with the diazo group. The contribution of the multicenter mechanism of deprotonation of the σ-complex with participation of water molecules was presumed to increase in going to the diazo components having electron-donor substituents.
- Kornev,Zheltov
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p. 1095 - 1099
(2007/10/03)
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- Triphendioxazine dyestuffs
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The novel triphendioxazine dyestuffs of the formula STR1 in which the substituents R, R', T1, T2, X, Y and n have the meanings given in the description are highly suitable for the dyeing and printing of cellulose-containing or amido-containing material.
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- Alkanol substituted disazo orange dye for nylon
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The specification describes a new group of alkanol substituted disazo compounds that are useful in dyeing polyamide textile fibers in orange hues. The new compounds are compatible with several acid blue dyes and several acid red dyes that are commercially important as dyes for nylon. The new compounds are particularly well suited for use as the "yellow" component in trichromatic systems for dying polyamide carpeting and other textiles. The new compounds are relatively inexpensive to make and have outstanding application and fastness properties. Other aspects of the specification are concerned with a method of making the new compounds and with a method of dyeing polyamides with said compounds and to the novel dyed polyamides resulting from the use of the new group of compounds as dyes.
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- Process for the preparation of aminoarylsulphonic acids in sulfolene solvent
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Aromatic aminosulphonic acids which have a reduced content of discoloring by-products are obtained when aromatic amines are reacted with a sulphonating agent in a reaction medium at least some of which consists of tetramethylene sulphone.
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- Barium laked phenylazonaphthalene dye containing sulfonic acid groups
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Azo dyes containing sulfonic acid groups laked with barium and derived from an anilinesulfonic acid as diazo component and a β-naphtholsulfonic acid as coupling component for example a dye of the formula STR1 The dyes are eminently suitable as pigments for coloring surface coating compositions, printing inks and particlarly resins.
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