• K Venkateswara Rao

      Articles written in Proceedings – Section A

    • Synthesis of ammonia from active nitrogen

      K Venkateswara Rao

      More Details Abstract Fulltext PDF

      Following the preliminary work of Joshi and Purushotham, the utilisability of active nitrogen for ammonia synthesis has been investigated in respect of 55 catalysts. These, when exposed to active nitrogen under certain conditions of temperature and pressure, form unstable nitrides or/and adsorption complexes, which react with hydrogen streamed subsequently so as to give ammonia. Yields were largest with tin-lead alloy >magnesium> tungstun>rose metal>tin.

    • Nuclear oxidation in the flavone series - Part II. Synthesis of norwogonin and isowogonin

      K Venkateswara Rao K Visweswara Rao T R Seshadri

      More Details Abstract Fulltext PDF

      The nuclear oxidation of chrysin and tectochrysin has been successfully effected using potassium persulphate. The first yields norwogonin and the second the 7-methyl-ether now named isowogonin. The method of oxidative demethylation of the 5- and 8-positions has also been employed for the preparation of isowogonin from 5∶7∶8-trimethoxy-flavone.

    • Nuclear oxidation in the flavone series - Part V. A new synthesis of wogonin

      K Venkateswara Rao K Visweswara Rao T R Seshadri

      More Details Abstract Fulltext PDF

      Using the new discovery of facile nuclear oxidation in hydroxy-flavones, (1) wogonin and (2) its 5-methyl ether have been synthesised. Starting with 7-O-benzyl-chrysin, oxidation followed by partial methylation and debenzylation yields (1) and by complete methylation and debenzylation hields (2).

    • Production ofJoshi-Effect in air under electrical discharge: The Rôle of sorbed chlorine

      K Venkateswara Rao

      More Details Abstract Fulltext PDF

      Observations ofJoshi-Effect Δi, were made in (a) air, (b) chlorine, (c) chlorine-air mixtures and (d) air with sorbed chlorine, under an ozoniser discharge, in the range 1–3 kilo-volts (r.m.s.), of 500 cycles frequency, using as detectors an oxide rectifier and a vacuo-junction connected in series. Theeffect was undetected with the available means in (a) even when mixed with traces of chlorine; it was as high as 80% current diminution in but ordinary light in (b) and (c), and remarkably enough also in (d). Whilstaging in (b) and (c) increased Δi. that in (d) reduced it. This decrease in (d), attributable to the desorption of chlorine, was markedly rapid when the system was filled with successive samples of air subjected to discharge and toplered out (but notdegassed); finally Δi was negligibly small as in (a). The large Δi in (d) is due to sorption of chlorine under conditions of discharge and not that resulting from prolonged contact of neutral chlorine with the container walls or streaming preactivated chlorine through the ozoniser. These results confirm Joshi's theory that an adsorption-like boundary layer formed under discharge is the chief seat of Δi.

      Compared with the oxide rectifier, the vacuo-junction recorded a lower Δi. Following Joshi, this is ascribed to a selective action of the former to some of the frequencies constituting the discharge current.

    • Light absorption by iodine vapour under conditions productive ofJoshi Effect

      K Venkateswara Rao

      More Details Abstract Fulltext PDF

      The absorption spectrum of iodine was studied using a special design (due to Prof. Joshi) ozoniser which provided an absorbing column of about 46 cms. Iodine vapour in presence of an annular film of I2, KI and KI3 excited in the above ozoniser, due to potentials varied in the range 0·5 to 1·5 kV of 50 cycles frequency gave a negativeJoshi Effect corresponding to a current decrease in ordinary light of 50–60%. The Effect %Δi is maximum near the threshold potential, Vm. The area of the surface exposed to the radiation is an important determinant of Δi. Under transverse irradiation Δi was much greater than under longitudinal one. The iodine glow near maximum Δi, was too feeble for spectroscopic record. Absorption spectra of unexcited iodine and for that under (transverse) irradiation at exciting potentials near maximumJoshi Effect were sensibly the same in respect of wavelength position of, and the intensity distribution amongst, the absorption bands. This applies to the iodine spectrum in Crookes’ tube discharge in dark and under ordinary and Hg-arc light. The main seat of the phenomenon may not be therefore in the bulk of the excited gas but in an adsorption-like boundary layer as postulated in Joshi’s Theory.

    • A convenient one-step synthesis of 3-acetyl-4-hydroxycoumarins

      K Venkateswara Rao V Sundaramurthy

      More Details Abstract Fulltext PDF

      The condensation ofp-bromophenylacetate with malonyl chloride under Friedel-Crafts reaction conditions results in the formation of 6-bromo-3-acety1-4-hydroxy-coumarin. This has been established on the basis of nmr, ir, uv and mass spectral data. The present procedure is applicable to substituted phenylacetates and is a facile one-step synthesis with considerably good yields.

    • Erratum

      K Venkateswara Rao V Sundaramurthy

      More Details Fulltext PDF
    • Reactivity of 2-hydroxy-ω-nitroacetophenones: Synthesis of 2-oximinocoumaranones

      K Venkateswara Rao V Sundaramurthy

      More Details Abstract Fulltext PDF

      2-Hydroxy-ω-nitroacetophenones prepared by the hydrolysis of 3-nitro-4-hydroxycoumarins were found to undergo a facile intramolecular cyclisation when heated with pyridine. The structures of the reaction products have been established by spectral characteristics and chemical methods as 2-oximinocoumaranones and comparison with an authentic synthetic sample in one case.

  •  

© 2021-2022 Indian Academy of Sciences, Bengaluru.