NOPR Collection:

New experimental results on oscillatory aerial oxidation of aldehydes

Tue, 01 Jan 1991 00:00:00 GMT

Title: New experimental results on oscillatory aerial oxidation of aldehydes Authors: Rastogi, R P; Das, Ishwar; Mishra, S B S; Jaiswal, Kiran Abstract: Some new experimental results on the oscillatory aerial oxidation of acetaldehyde, propionaldehyde and benzaldehyde in 90% acetic acid containing cobalt (II) acetate and sodium bromide are reported. It has been observed that benzaldehyde can be replaced by acetaldehyde or propionaldehyde but not by formaldehyde. Oscillations are not observed when cobalt (II) acetat, is replaced by cobalt nitrate, cuprous chloride, cupric acetate and manganese acetate. Bromate ion or liquid bromine. However, can replace sodium bromide. Certain additives, viz., CCI₄, Hg²⁺ ions, KI, I₂, phenol. aniline, 1,10-phenanthroline, ethylenediamine, acetylacetone and hydroquinone quench the oscillations. Addition of sodium chloride to the oscillatory system yields different types of colour oscillations (blue⇌olive green) instead of pink to brown. A semi-batch reactor has been used to study oscillatory system containing acetaldehyde under controlled conditions of temperature. oxygen flow-rate and the reactant concentrations. Page(s): 1-6

Liquid membrane phenomena: Steady state energy conversion for composite membranes generated by cholesterol

Tue, 01 Jan 1991 00:00:00 GMT

Title: Liquid membrane phenomena: Steady state energy conversion for composite membranes generated by cholesterol Authors: Jain, Abhay K; Srivastava, Rajesh K; Gupta, Manoj K; Das, Suresh K Abstract: The efficiencies of electro-kinetic energy conversion across composite liquid membranes generated by cholesterol on one side and both sides of the supporting membrane have been evaluated for both electroosmosis and streaming potential. The efficiencies of energy conversion have also been calculated across cholesterol liquid membranes alone in the absence of supporting membrane. The results thus obtained have been found to be consistent with the linear theories of steady state thermodynamics. An attempt has been made to relate the maximum conversion efficiency characterizing the series composite membrane as a whole with the maximum conversion efficiency for its constituent membrane elements. Substitution of the values of various experimentally evaluated parameters into the relationship developed for series membrane yields results in fair agreement for the situation when cholesterol liquid membrane is generated on one side of the supporting membrane interface. Page(s): 7-12

Photosensitized energy transfer reactions of tris(4,4'-dialkyl-2,2' -bipyridine )ruthenium(ll) complexes with substituted styrylpyridines

Tue, 01 Jan 1991 00:00:00 GMT

Title: Photosensitized energy transfer reactions of tris(4,4'-dialkyl-2,2' -bipyridine )ruthenium(ll) complexes with substituted styrylpyridines Authors: Rajagopal, S; Rajendran, T; Srinivasan, C Abstract: The quenching rate constants (k_q) of quenching of excited *RuL complexes (L is 4,4'-dialkyl- 2,2' -bipyridine) by substituted styrylpyridines are neither influenced by increase in size of the alkyl group of the sensitizer nor by the substituent in the quencher and energy transfer seems to be predominant. However, in the quenching of *RuL by 4'-nitro-4-styrylpyridine and 4-methyl-4-styrylpyridinium iodide both electron transfer and energy transfer seem to occur. Page(s): 13-15

Carboxylato bound chromium (V ) oxidation of potassium hexachloroiridate(lll) & potassium tetrachloroplatinate(ll)

Tue, 01 Jan 1991 00:00:00 GMT

Title: Carboxylato bound chromium (V ) oxidation of potassium hexachloroiridate(lll) & potassium tetrachloroplatinate(ll) Authors: Rajavelu, A; Srinivasan, Vangalur S Abstract: Carboxylato bound chromium(V) oxidises hexachloroiridate(IlI) in acetate-acetic acid buffer at pH 4.1 and 30 ± 0.2°C. The reaction proceeds via the formation of a highly absorbing species whose formation and decay have been studied. Under the same conditions, the reaction between potassium tetrachloroplatinate( ill) and oxochromate(V) exhibits total second order kinetics-first order with respect to each reactant. As Ir(Ill) forms a complex with the unbound ligand, the rate of reduction of Cr(V) increases with increase in [unbound carboxylic acid] and in contrast, the added carboxylic acid has little effect on Cr(V)-Pt(II) reaction. As 1 mol of Cr(V) needs 2 mol of Ir(III), the precursor complex formed between Cr(V) and Ir(Ill) through a chloro bridge, possibly undergoes 1 electron transfer in the slow step. The chromium(IV) complex in the second stage induces electron transfer in mandelatopentaamminecobalt(lll) complex, yielding cobalt(ll). Although 1mol of Cr(V) oxidises 1mol of Pt(II), in the presence of mandelatopentaamminecobalt (III) complex, 1 mol of Cr(V) oxidises about 0.70 mol of Pt{II) yielding about 40% of cobalt(II), indicating the formation of intermediate chromium(IV) in this reaction also. Page(s): 16-20