Sulphuric Acid polarography

Polarography of Carbonium Ions in Acid Solution, Part I, The Triphenylmethyl Ion in Sulphuric Acid, P.H. Plesch and I. Sestakova, Journal of the Chemical Society, (B), 1970, 87-92. 

Delocalised radical-zwitterions are formed also from other aromatic tt-systems bearing a positive charge. Tropylium salts 2 show a one-electron reduction wave on polarography in acetonitrile with E>/, = -0.17 V vr. see [26], The zwitterion is more stable in 6 M sulphuric acid where a second one-electron wave is seen at... 

Determination of iron in sulphuric acid by square-wave Polarography. 

Digestion with hydrofluoric acid-sulphuric acid followed by fusion of residue in sodium carbonate. Polarography... 

For quantitative evaluation, sample- and standard solution are chromatographed on the same layer, the zones of active substance locahsed in UV fight or after spraying a reference strip, scraped off and extracted with 0.2 N sulphuric acid [130] or 0.05 N hydrochloric acid. The determination is then carried out by photometry, polarography, spectrophotometry [130, 143] or spectrofluorometry. 

The ability of phosphines to act as either one-electron acceptors or one-electron donors may be crucial in the mechanism of their cytotoxicity and allow them to interfere with electron transport processes. Phosphinium radical cations have been generated by oxidation of phosphines at a mercury anode or by y-irradiation of tertiary phosphines on silica and in sulphuric acid The oxidation potentials appear to be within the range accessible to biological systems Aryl phosphines are more easily oxidised than alkyl phosphines Ejq (polarography in CH3CN, anodic oxidation) PPha -H 50 mV, PEt3 - 415 Phosphine dimer cation radicals (R3PPR3) have been identified by... 

Polarography of Organic Cations in Acid Solutions. Part 3. Three 1,1 -Diarylethyl Ions in Sulphuric and Methanesulphonic Acids, Kabir-ud-Din and P.H. Plesch, Journal of the Chemical Society, Perkin II, 1978, 892-895. 

Polarography has been successfully applied to the investigation of structural problems involving sulphur compounds. The presence of a disulphide bond has been established by means of the polarographic reduction waves of cytochrome C (156) and lipoic acid (757), and in cyclic disulphides of the oxytocine and vasopressine type (158). The elucidation of the process responsible for the reduction wave of lipoic acid was carried out by comparison with reduction waves of cyclic disulphides, where the disulphide bond was incorporated into rings of various size. The similarity indicated that in lipoic acid an S—S bond which is a part of a larger cyclic system is reduced. 

Henry et al. [26] reported a method for the determination of As(III), As(V) and total inorganic arsenic by differential pulse polarography. As(III) was measured directly in 1M perchloric acid or 1M hydrochloric acid. Total inorganic arsenic was determined in either of these supporting electrolytes after the reduction of electroinactive As(V) with aqueous sulphur dioxide. As(V) was evaluated by difference. Sulphur dioxide was selected because it reduced As(V) rapidly and quantitatively, and excess reagent was readily removed from the reaction mixture. 

Fundamental properties are revealed in kinetic acidity studies (the kinetic acidity of m-CF3CgH4SMe is greater than that of the selenium analogue by a factor of 1.38), polarography (RSCH2CH2COCO2R is protonated at a carbonyl group rather than at sulphur), voltammetry (three successive anodic peaks for Ph2Se at Pt in MeCN), and complexation enthalpies of l,cu-bis-(n-butylthio)alkanes with... 

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