Chronopotentiometric studies of certain biologically important compounds at tubular graphite electrode

1991 ◽  
Vol 56 (9) ◽  
pp. 1833-1837
Author(s):  
Ram Parkash ◽  
Hari Om Gupta ◽  
Jatinder Dutt
Keyword(s):  
Sulfuric Acid ◽  
Graphite Electrode ◽  
Lone Pair ◽  
Cation Radical ◽  
Phenothiazine Derivatives ◽  
Solution Flow ◽  
Single Wave ◽  
Acidic Solutions ◽  
Flow Through ◽  
Hydrodynamic Systems

The chronopotentiometric studies of certain phenothiazines in hydrodynamic systems at a solution flow-through tubular graphite electrode were carried out in sulfuric acid of different concentrations. A well-defined single wave (involving 2 electrons) in 0.1M H2SO4 and two waves (involving 1 electron each) in 2.0M H2SO4 were observed. Phenothiazines are oxidized trough the formation of a monocation radical by the elimination of one electron from the lone pair of N-atom. The monocation radical is stable in sulfuric acid of a moderate concentration and is unstable in neutral or less acidic solutions. The cation radical undergoes instantaneous hydrolysis yielding sulfoxide, thus presenting an overall two-electron oxidation of the phenothiazine derivatives. The suitability of the chronopotentiometric technique for their determination was established.

Applicability Test of Glass Lining Material for High-Temperature Acidic Solutions of Sulfuric Acid in Thermochemical Water-Splitting IS Process

2010 ◽  
Vol 36 (4) ◽  
pp. 413-419 ◽  
Author(s):  
Jin Iwatsuki ◽  
Nobuyuki Tanaka ◽  
Yutaka Watanabe ◽  
Atsuhiko Terada ◽  
Kaoru Onuki
Keyword(s):  
Sulfuric Acid ◽  
High Temperature ◽  
Water Splitting ◽  
Acidic Solutions ◽  
Lining Material

Lanthanum accumalation from acidic solutions using aCitrobacter sp. immobilized in a flow-through bioreactor

1995 ◽  
Vol 14 (3-4) ◽  
pp. 271-280 ◽  
Author(s):  
Mark R. Tolley ◽  
Laura F. Strachan ◽  
Lynne E. Macaskie
Keyword(s):  
Acidic Solutions ◽  
Flow Through

Effect of thioridazine and chlorpromazine on rat liver hemodynamics

1960 ◽  
Vol 199 (5) ◽  
pp. 793-796 ◽  
Author(s):  
Gabriel L. Plaa ◽  
Edwin C. McGough ◽  
Gerry J. Blacker ◽  
James M. Fujimoto
Keyword(s):  
Mean Arterial Pressure ◽  
Marked Decrease ◽  
Portal Pressure ◽  
Liver Ischemia ◽  
Phenothiazine Derivatives ◽  
Perfusate Flow ◽  
Flow Through ◽  
Liver Hemodynamics ◽  
Rat Livers ◽  
Higher Doses

Evidence is presented which indicates that two phenothiazine derivatives—thiroidazine and chlorpromazine— increase hepatic vascular resistance in isolated perfused rat livers. These substances produce the following: a) a decrease in perfusate flow through the organ, b) an increase in portal pressure and c) a decrease in organ weight. These effects were demonstrated with doses as low as 4 mg but were quantitatively more pronounced and of longer duration with higher doses. Tachyphylaxis did not occur. The effects could be blocked with sodium nitrite. Both phenothiazines were found to produce liver ischemia in anesthetized, laparotomized rats. Thioridazine was found to raise portal pressure in anesthetized, laparotomized cats in spite of a marked decrease in mean arterial pressure.

A 13C nuclear magnetic resonance study of aliphatic ketone protonation in sulfuric acid solutions

1976 ◽  
Vol 54 (5) ◽  
pp. 718-725 ◽  
Author(s):  
Robert A. McClelland ◽  
William F. Reynolds
Keyword(s):  
Sulfuric Acid ◽  
Molecular Size ◽  
Nuclear Magnetic Resonance Study ◽  
Suitable Alternative ◽  
Acidic Solutions ◽  
H Nmr ◽  
Organic Bases ◽  
13C Nuclear Magnetic Resonance ◽  
Sulfuric Acid Solutions ◽  
C Nmr

A 13C nmr investigation of the protonation in sulfuric acid of the aliphatic ketones MeCOR (R = Me, Et, i-Pr, tert-Bu), 3-pentanone, and the cyclic ketones from cyclobutanone through cyclooctanone is reported. With the exception of cyclobutanone which is considerably less basic, these ketones are all very similar in their basicity, with half-protonation in the region 73–78% H2SO4. The acidity dependence of the protonation is discussed; there appears to be a small dependence on molecular size. 13C nmr is shown to be a suitable alternative to 1H nmr in the study of the protonation of weak organic bases in strongly acidic solutions.

Complexes of sulfuric acid with N,N-dimethylformamide: An ab initio investigation

2012 ◽  
Vol 85 (1) ◽  
pp. 225-236 ◽  
Author(s):  
Liubov P. Safonova ◽  
Michail G. Kiselev ◽  
Irina V. Fedorova
Keyword(s):  
Charge Transfer ◽  
Sulfuric Acid ◽  
Natural Bond Orbital ◽  
Bond Formation ◽  
Lone Pair ◽  
Nbo Analysis ◽  
Basis Set ◽  
Antibonding Orbital ◽  
Binary Complexes ◽  
First Time

The (H2SO4)2, H2SO4-DMF, and (H2SO4)2-DMF complexes have been investigated, using the B3LYP functional with cc-pVQZ basis set. The characteristics of structure and energetics for binary complexes of sulfuric acid with dimethylformamide (DMF) have been obtained for the first time. The H-bond formation both between molecules of sulfuric acid as well as sulfuric acid-DMF were studied, on the basis of Weinhold’s natural bond orbital (NBO) analysis. It was shown that the H-bond formation between sulfuric acid and DMF molecules is stronger than ones for the acids dimer. The value of charge transfer from lone pair (LP) orbitals of DMF oxygen to the antibonding orbital of acid OH-bond significantly exceeds the criterion of H-bond existance (0.01 e). As follows from energy, among the complexes under investigation the most preferable one was found to be (H2SO4)2-DMF in which sulfuric acid molecules are linked with each other by three H-bonds.

ORGANIC AND BIOLOGICAL SPECTROCHEMICAL STUDIES: XXIII. CONFORMATION OF THE p-DIMETHOXYBENZENE CATION RADICAL IN CONCENTRATED SULFURIC ACID

1966 ◽  
Vol 44 (13) ◽  
pp. 1501-1512 ◽  
Author(s):  
W. F. Forbes ◽  
P. D. Sullivan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Electron Spin Resonance ◽  
Sulfuric Acid ◽  
Magnetic Resonance ◽  
Electron Spin ◽  
Cation Radical ◽  
Molecular Orbital Calculations ◽  
Spin Resonance ◽  
Concentrated Sulfuric Acid ◽  
Nuclear Magnetic

The electron spin resonance spectrum of the p-dimethoxybenzene cation radical in concentrated sulfuric acid is interpreted in terms of cis–trans isomerism. Empirical molecular orbital calculations support these assignments. The two isomers are found to possess slightly different "g" values, Δg (cis – trans) being ca. 1.8 × 10−5.Nuclear magnetic resonance and ultraviolet data show that the radical exists in equilibrium with the neutral non-radical species at room temperature, but that sulfonation occurs at higher temperatures. Nuclear magnetic resonance and electron spin resonance data of solutions of p-dimethoxybenzene in D2SO4 show that rapid exchange of the ring protons occurs.

Effect of the Pore Formation on the Solution Flow through Acrylamide Gel

1999 ◽  
Vol 600 ◽  
Author(s):  
H. Tamagawa ◽  
S. Popovic ◽  
M. Taya
Keyword(s):  
Flow Rate ◽  
Pore Volume ◽  
Pore Formation ◽  
Volume Fraction ◽  
Synthesis Method ◽  
Solution Flow Rate ◽  
Gelation Temperature ◽  
Solution Flow ◽  
Pore Volume Fraction ◽  
Flow Through

AbstractA simple synthesis method of porous acrylamide gel is proposed. Pore formation in gel body is dominated by the amount of polymerization initiator, accelerator and gelation temperature. We investigated the influence of these factors on the number and the size of pores. Gelation temperature control is the easiest and the most effective way to create a number of large pores in a gel body. We also investigated the pore volume fraction dependence of solution flow through the gels. Solution flow rate was found to be promoted with the increase of pore volume fraction.

FREE RADICALS OF BIOLOGICAL INTEREST: I. ELECTRON SPIN RESONANCE SPECTRA OF TOBACCO SMOKE CONDENSATES

1967 ◽  
Vol 45 (7) ◽  
pp. 1087-1098 ◽  
Author(s):  
W. F. Forbes ◽  
J. C. Robinson ◽  
G. F. Wright
Keyword(s):  
Free Radicals ◽  
Electron Spin Resonance ◽  
Sulfuric Acid ◽  
Electron Spin ◽  
Tobacco Smoke ◽  
Cation Radical ◽  
Fold Increase ◽  
Active Centers ◽  
Radical Species ◽  
Spin Resonance

Smoke condensates, prepared from tobacco smoke, are shown to contain a variety of paramagnetically active centers. Some of these have lifetimes of a few seconds. Smoke condensates, when dissolved in sulfuric acid, give rise to at least two cation radical species. The more short-lived species may be the anthracene or an anthracene-type cation radical species and the more long-lived one may be a cation radical related to, but not identical with, the 3,4-benzpyrene cation radical.When 3,4-benzpyrene is heated to near its melting point, considerably more intense electron spin resonance (e.s.r.) spectra are obtained. The heated benzpyrene sample, when dissolved in sulfuric acid, also gives a more intense, but otherwise similar, spectrum than an unheated sample. These observations indicate that, on heating benzpyrene, additional free radicals are formed, and this may account for the relatively high carcinogenicity of tobacco smoke condensates.The e.s.r. spectrum of 3,4-benzpyrene in sulfuric acid undergoes an approximately 10-fold increase in signal intensity when similar amounts of 3,4-benzpyrene-6,7-quinone are added to the mixture. The latter compound on its own does not afford a detectable signal under these conditions. This indicates that the ability of known carcinogenic substances, such as 3,4-benzpyrene, to give rise to free-radical species can be appreciably affected by the molecular environment.

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