scholarly journals Complexes of peracetylated cyclodextrin in a non-aqueous aprotic medium: the role of residual water

2015 ◽  
Vol 17 (26) ◽  
pp. 17380-17390 ◽  
Author(s):  
Laszlo Jicsinszky ◽  
Katia Martina ◽  
Marina Caporaso ◽  
Pedro Cintas ◽  
Andrea Zanichelli ◽  
...  
Keyword(s):  
Stability Constants ◽  
Residual Water ◽  
Aprotic Medium ◽  
Stability Constants Of Complexes ◽  
Apparent Stability

Not all peracetylated cyclodextrins can be completely dried and water protons can be invisible due to the overlapping signals of the acetyl groups. Apparent stability constants of complexes were also calculated.

Reaction in ion exchangers. Apparent stability constants of complexes and salting-in (out) effects

1988 ◽  
Vol 7 (2-3) ◽  
pp. 111-122 ◽  
Author(s):  
M Metayer ◽  
D Langevin ◽  
M Hankaoui ◽  
B Pollet ◽  
M Labbe ◽  
...  
Keyword(s):  
Stability Constants ◽  
Ion Exchangers ◽  
Stability Constants Of Complexes ◽  
Apparent Stability

Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes

1985 ◽  
Vol 50 (3) ◽  
pp. 581-599 ◽  
Author(s):  
Petr Vaňura ◽  
Emanuel Makrlík
Keyword(s):  
Stability Constants ◽  
Organic Phase ◽  
Equilibrium Constants ◽  
Minor Role ◽  
Nitrobenzene Solution ◽  
Ligand Structure ◽  
Stability Constants Of Complexes ◽  
Separation Factors ◽  
The Stability ◽  
A Minor

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.

Studies on the Coordination Reaction of VO2+ and Tannic Acid in the Tannin Extract Desulfurization

2012 ◽  
Vol 239-240 ◽  
pp. 1573-1576
Author(s):  
Zhu Qing Gao ◽  
Xiao Dong Cai ◽  
Kai Cheng Ling
Keyword(s):  
Stability Constants ◽  
Tannic Acid ◽  
Ph Value ◽  
Protonation Constants ◽  
Conditional Stability ◽  
Tannin Extract ◽  
Acid Effect ◽  
Different Temperatures ◽  
The Stability ◽  
Apparent Stability

At different temperatures, the protonation constants of tannic acid and the complex apparent stability constants between tannic acid and VO2+ were determined by using pH potentimetric method. The results showed that the protonation constants and the complex apparent stability constants slightly decreased with the raising temperature. In accordance with the pH value in the tannin extract technology, the conditional stability constants of the complex were calculated on the basis of the acid effect of tannic acid and the hydrolysis effect of VO2+. It was found that pH greatly affected the stability constants of the complex , so pH must be strictly controlled in the tannin extract technology.

Catalytic-thermometric determination of stability constants of complexes using the iodine-azide reaction

1986 ◽  
Vol 103 (2) ◽  
pp. 325-332 ◽  
Author(s):  
M.C.García Alvarez-Coque ◽  
R.M.Villanueva Camaãs ◽  
G.Ramis Ramos ◽  
M.J.Medina Hernández ◽  
C.Mongay Fernández
Keyword(s):  
Stability Constants ◽  
Stability Constants Of Complexes ◽  
Thermometric Determination

Oxidising Role of Water Vapour in the 250 Kev D+ Induced Radiolysis of Polyimide Kapton-H

1988 ◽  
Vol 100 ◽  
Author(s):  
U. K. Chaturvedi ◽  
A. Patnaik ◽  
Ramji Pathak ◽  
R. N. Chakraborty ◽  
A. K. Nigam
Keyword(s):  
Partial Pressure ◽  
Water Vapour ◽  
Ion Beam ◽  
Adsorbed Water ◽  
Vacuum System ◽  
Residual Water ◽  
Implantation Time ◽  
Polymeric Surface ◽  
Imide Ring

Residual water vapour present in the vacuum system has been observed to play a dominant oxidising role in the 250 keV D+ induced radiolysis of polyimide (Kapton-H). The partial pressure (pp) of water in the vacuum system decreases sharply as the D+ beam impinges the polymeric surface, but soon after, it recovers to its initial value as the accumulated dose increases. Emission of CO2 is observed which has its maximum at a time when the H2O partial pressure is at a minimum. The CO2 level also returns to its original level with time. This complementary variation of CO2 and H2O confirms that absorbed and adsorbed water molecules are radiolysed by the ion beam and initiate oxidation of the radiolytically evolved CO to yield CO2 on and within the ion implanted surface of the polyimide. Further, the small enhancement in the 28 amu peak (N2 + CO), which exhibits no maximum/minimum over the entire implantation time, can be understood in terms of the evolution of N2 from the imide ring as a result of radiolysis of this nitrogen containing polymers.

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