• M Palanichamy

      Articles written in Journal of Chemical Sciences

    • Studies on Schiff base complexes: Formation constants of Cu(II), Ni(II) and Zn(II) complexes on N-salicylidene-L-valinate, L-phenylalaninate and L-tryptophanate systems

      K Rengaraj B Sivasankar M Anbu M Palanichamy

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      The computer-based analysis of pH titration data obtained for the determination of the stability constants of M-A-B [M=Ni(II), Cu(II) or Zn(II), A=salicylaldehyde(Sal) and B=L-valine (Val), L-phenylalanine (Phe) and L-tryptophan (Trp) and AB the corresponding Schiff base] indicates preference for the formation of Schiff base complexes rather than the ligands binding as such to the metal ions without fusion of rings. The presence of aliphatic or aromatic side chains in the amino acids has no effect on the basicities of the coordinating sites of the Schiff bases. This is shown by the similarity of stability constant values for different Schiff base complex species.

    • Potentiometric investigation of Schiff base equilibria involving salicylaldehyde and tridentateα-aminoacids with Cu(II), Ni(II) and Zn(II) in aqueous medium

      M Palanichamy M Anbu

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      Potentiometric determination of equilibrium constants and species distribution of Schiff base complexes, in aqueous solution, involving salicylaldehyde (A) and tridentateα-amino acids (B)(L-threonine, L-glutamine and L-glutamic acid) with metal ions Cu(II), Ni(II) and Zn(II)(M) indicates preference for the formation of Schiff base complexes rather than the ligands binding as such to the metal ions. Binary stability constants follow the Irving-Williams order Cu(II)>Ni(II)>Zn(II). The influence of additional coordination sites such as -OH, -CONH2 and -COOH in the formation of ternary complexes is also discussed.

    • Alkylation of phenol with methanol over ion-exchanged Y-zeolites

      V V Balasubramanian V Umamaheshwari I Sudarsan Kumar M Palanichamy V Murugesan

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      Alkylation of phenol with methanol was carried out over Lewis acid ion exchangedY-zeolites, FeY, ZnY, CdY and LaY at temperatures of 523, 573, 623, 673 and 698 K. The products obtained wereo-cresol, 2,6-xylenol and anisole. The effects of phenol to methanol mole ratio and Weight Hourly Space Velocity (WHSV) were examined for high phenol conversion and product selectivity. Phenol conversion decreased with increase of temperature over all the catalysts due to coke deposition. Selectivity too-cresol decreased with increase of temperature as it, once formed, became the reactant for formation of 2,6-xylenol. Selectivity to 2,6-xylenol increased with increase of temperature indicating high activation energy for its formation. Selectivity to anisole, although formed less than 10% over all the catalysts, decreased with increase of temperature due to its conversion too-cresol and then to 2,6-xylenol. In addition, selectivity to anisole also decreased with decrease of phenol to methanol feed ratio and WHSV. The study of time on stream showed preferential blocking of strong acid sites by coke deposits and hence these site dependent formations ofo-cresol and 2,6-xylenol were greatly reduced but free weak acid site dependent anisole formation increased with time.

    • Hydration of ethylene in the vapour phase over NAPO-5 and ZAPO-5

      C Kannan S P Elangovan M Palanichamy V Murugesan

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      Hydration of ethylene in the vapour phase over NAPO-5 and ZAPO-5 molecular sieves has been carried out between 300 and 450°C. The products formed are isobutanol, ethanol andn-butanol. The effects of temperature, time on stream and partial pressure of water vapour on ethylene conversion and products selectivity have been studied. Increase of the partial pressure of water vapour increased the selectivity of ethanol andn-butanol, but decreased the selectivity of isobutanol. Formation of ethanol andn-butanol is observed to be dependent on Bronsted acidity whereas formation of isobutanol is proved to be dependent on both Bronsted and Lewis acidities.

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