Pushkin M. Qureshi

Anion-exchange initiation of reactions: Detection and spectrophotometric determination of aliphatic amines with 2,4-dinitrophenylhydrazine

The role of anion-exchange resin beads in the initiation of reactions of tertiary amines with 2,4-dinitrophenylhydrazine has been explored. This reagent has been used for the selective detection and determination of aliphatic amines. Radiochemical studies have been performed to show that the coloured species is adsorbed but not exchanged on ion-exchange beads. A model for the interaction is proposed.

Fresh evidence for proposed zwitterionic intermediates.

A new selective and sensitive method for the detection of aliphatic amines has been developed with chloride-form anion-exchange resins and 2,4-dinitrotoluene. The reaction with tertiary amines can only be explained in terms of hitherto postulated zwitterionic intermediates.

Chromatographic Behavior of 43 Cations on Silica Gel G in Acetone-Formic Acid Systems

Abstract A systematic study of the chromatographic behavior or 43 metal ions has been carried out in Acetone-Formic Acid systems on thin layers of Silical Gel G. The separation potential of these systems has been investigated for numerous metal ions and a number of useful and interesting separations have been predicted. The results obtained have been discussed and analysed.

Evaluation of ε for p-dinitrobenzene—aniline complexes by the Scott equation. Failure of the Benesi—Hildebrand equation

Abstract The Scott equation has been employed to determine e for p -dinitrobenzene charge transfer complexes with anilines. It is seen that the Benesi—Hildebrand plots show a random scatter, whereas the Scott plots are satisfactory straight lines.

Note on the effect of activity coefficients on the NMR association constants for the 2,4-dinitrotoluene-diphenylamine system. The Qureshi-Varshney-Kamoonpuri equation. Possible role of hydrogen bonding

Abstract The NMR studies of the charge transfer complex between 2,4-dinitrotoluene and diphenylamine in CCl 4 are reinvestigated. The proposed Qureshi - Varshney - Kamoonpuri equation shows that activity coefficients have a profound effect on the NMR association constants. The possibility of hydrogen bonding in the system has also been considered.

A novel and sensitive spot-test for m-dinitroaromatics and their derivatives with sodium sulphite and dimethylsulphoxide

Sodium sulphite has been used for a very sensitive characterization of m-dinitroaromatics and their derivatives, with dimethylsulphoxide as solvent.

Specific solid-state detection and semiquantitative determination of catechol and o-nitrophenol and some of their kinetic parameters

Catechol and o-nitrophenol have been determined successfully in the solid state by means of their solid-state reaction with soda-lime. The glass-wool plug modification has been used with advantage in the determination of o-nitrophenol. The reaction mechanism is postulated on the basis of the reflectance electronic spectra. Some solid-solid kinetic parameters have also been studied.

Charge transfer vs hydrogen bonding; effect of concentration on the equilibria of the interaction of dinitrobenzenes and anilines

Abstract Various studies, such as spectrophotometry, solubility studies and FT—NMR studies reveal that the interaction of dinitrobenzenes with anilines is primarily due to charge transfer but in some cases, where very concentrated solutions are involved, hydrogen bonding may dominate over charge transfer.

Diphenylamine as an n and π donor in the solid-state reaction of 2,4-dinitrotoluene with diphenylamine

Abstract The kinetics and mechanism of the reaction of 2,4-dinitrotoluene with diphenylamine were studied in the solid state. The reaction product is a charge transfer complex with a localized intermolecular interaction as shown by uv and ir spectroscopy. The solid-state studies were complemented by some NMR studies in CCl4. A novel feature of the study reveals that diphenylamine in this case is a much more powerful n donor than a π donor.

Kinetic method of analysis for an important pharmaceutical 2,4-dinitrophenylhydrazine

A new selective method for the kinetic analysis of 2,4-dinitrophenylhydrazine with piperidine in dimethylsulfoxide is described. As most colorimetric methods for polynitroaromatics are handicapped owing to the formation of unstable colours, the kinetic method may therefore seem attractive. The method can determine 2,4-dinitrophenylhydrazine in the range 0–120 ppm.