Dihydroxyanthraquinone complexes of zirconium

The nature of the zirconium complexes of alizarin red S (1,2-dihydroxy- anthraquinone-3-sulphonate), alizarin (1,2-dihydroxyanthraquinone), and hystazarin (2,3-dihydroxyanthraquinone) were studied using spectrophotometric, kinetic, and voltammetric techniques. In HClO4- NaClO4, 75% methanol media, these compounds form 1 : 1 complexes with zirconium. The equilibrium constants, KC, for the reaction of zirconium with alizarin red S, alizarin, and hystazarin were found to be 2.8 x 105, 3.0 x 103, and 6.9 x 102, respectively, at 25� and μ = 1.0M. The concentration acid dissociation constants, pKca, for the dihydroxyanthraquinones in 75% methanol were determined as: alizarin red S 6.71 and 11.35; alizarin 7.31 and 11.84; hystazarin 7.57 and 11.40; at 25� and μ 1.0M. Zirconium reacts slowly with alizarin red S and alizarin, and mainly via the hydrolysed Zr(OH)22+ species, whereas the reaction with hystazarin is rapid. Rate constants were determined for the first two reactions. The zirconium-alizarin red S complex includes two coordinated hydroxyl groups, the alizarin complex one, and the hystazarin complex contains none. It is suggested that these coordinated hydroxyl groups hydrogen-bond to the sulphonate and/or quinone groups and enhance both the stability and colour of the zirconium complexes.

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Decomposition of some cyclic dithiocarbamates

Canadian Journal of Chemistry ◽

10.1139/v70-368 ◽

1970 ◽

Vol 48 (14) ◽

pp. 2204-2209 ◽

Cited By ~ 9

Author(s):

Ronald R. Vandebeek ◽

Serge J. Joris ◽

Keijo I. Aspila ◽

Chuni L. Chakrabarti

Keyword(s):

Dielectric Constant ◽

Dissociation Constants ◽

Acid Dissociation ◽

Acid Molecule ◽

Decomposition Rates ◽

Acid Dissociation Constants ◽

Ring Strain ◽

Relative Stabilities ◽

Ph Values ◽

The Stability

The stability of some cyclic N,N-disubstituted dithiocarbamates has been studied by the analysis of the decomposition rates at different pH values. It is concluded that the most important factors which determine the relative stabilities of three cyclic dithiocarbamates (DTC) are the solvation of the DTC acid molecule and the ring strain associated with the substituents. This has been proven by a study of (a) the decomposition rates as a function of the dielectric constant of the medium, (b) order of the stability, and (c) activation energy.The molar absorptivities and the apparent acid dissociation constants have been determined for pyrrolidine-, piperidine-, and hexamethylene-dithiocarbamates.

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The correlation of the stability constants of 1,3-dicarbonylic monochelates of Iron(III) with the acid dissociation constants of the ligand

Journal of Solution Chemistry ◽

10.1007/bf00652544 ◽

1990 ◽

Vol 19 (12) ◽

pp. 1191-1197 ◽

Cited By ~ 5

Author(s):

Jos� M. Hernando ◽

Olimpio Montero ◽

Carlos Blanco

Keyword(s):

Stability Constants ◽

Dissociation Constants ◽

Acid Dissociation ◽

Acid Dissociation Constants ◽

The Stability

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Equilibrium studies on lithium(I) transfer into ionic liquid with a water-soluble octabromoporphyrin (H2(OBTMPyP)4+) from aqueous phase

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s108842460900111x ◽

2009 ◽

Vol 13 (08n09) ◽

pp. 849-853 ◽

Cited By ~ 2

Author(s):

Takuya Shimomura ◽

Masaaki Tabata ◽

Jun Nishimoto

Keyword(s):

Aqueous Solution ◽

Ionic Liquid ◽

Ion Exchange ◽

Dissociation Constants ◽

Equilibrium Constants ◽

Water Soluble ◽

Acid Dissociation ◽

Acid Dissociation Constants ◽

Equilibrium Studies ◽

Counter Ions

A water-soluble octabromoporphyrin 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin (H2(OBTMPyP)4+), H2P4+) and its lithium complex, Li(OBTMPyP)3+ , (LiP3+) , transferred quantitatively to an ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM+PF6-) with no addition of other counter ions. The acid-dissociation constants of H2(OBTMPyP)4+ between aqueous and BMIM+PF6- phases were determined spectrophotometrically and found to be 10-7.67 and 10-11.33 at I = 0.1 for K a1,IL = [H+]aq[HP3+]IL/[H2P4+]IL and K a2,IL = [H+]aq[P2+]IL/[HP3+]IL , respectively. Since the acid-dissociation constants involve the partition of H2(OBTMPyP)4+ between aqueous and IL phases, the determined values are ten times as low as those observed in aqueous solution. The transfer equilibrium constants of LiP3+ and NaP3+ to IL defined by K MP,IL = [MP3+]IL/[M+]aq[P2+]IL (M = Li+ or Na+) were found to be 104.83 and 101.31 for K LiP,IL and KNaP,IL , respectively. LiP3+ transferred selectively in the presence of Na+ (K LiP,IL /K NaP,IL = 103.52) to IL phase through an ion-exchange mechanism between BMIM+PF6- and Li(OBTMPyP)3+ .

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Kinetics and Mechanism of the Isomerization of 1H-Indene-1-carboxylic Acid to 1H-Indene-3-carboxylic Acid in Aqueous Solution and Determination of Their Keto-Enol Equilibrium Constants and Acid Dissociation Constants of the Keto and Enol Forms. Implication for the Photolysis of Diazonaphthoquinones

Journal of the American Chemical Society ◽

10.1021/ja00082a017 ◽

1994 ◽

Vol 116 (3) ◽

pp. 961-967 ◽

Cited By ~ 14

Author(s):

J. Andraos ◽

A. J. Kresge ◽

V. V. Popik

Keyword(s):

Aqueous Solution ◽

Carboxylic Acid ◽

Dissociation Constants ◽

Equilibrium Constants ◽

Kinetics And Mechanism ◽

Acid Dissociation ◽

Acid Dissociation Constants

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Equilibria in the halogenation of some organic substances in aqueous solution

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1952.0002 ◽

1952 ◽

Vol 210 (1102) ◽

pp. 310-322 ◽

Cited By ~ 10

Keyword(s):

Gas Phase ◽

Dissociation Constants ◽

Equilibrium Constants ◽

Mean Value ◽

Acid Dissociation ◽

Organic Substances ◽

Kcal Mole ◽

Acid Dissociation Constants ◽

The Mean ◽

Better Than

Measurements of redox potential have been used to obtain equilibrium constants for the reaction of iodine and bromine with aqueous solutions of ketones, esters and nitro-paraffins. Many of the iodination constants have an accuracy of a few per cent, but the bromination constants are not reliable to better than a power of ten. The iodination constants vary over 10 powers of ten, corresponding to considerable differences in the nature of the carbonhydrogen and carbon-iodine bonds involved. The data are used to derive the heat of the reaction R H + I-> R I + H in the gas phase, and the mean value obtained (46 kcal/mole) is consistent with earlier estimates. Approximate values are also derived for the equilibrium constants of the reaction R I->R - + I + in solution. For variations in R these are roughly parallel with the acid dissociation constants of the reaction R H->R - + H + .

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Solution speciation in the aqueous Na(I)–EDTA and K(I)–EDTA systems

Canadian Journal of Chemistry ◽

10.1139/v93-100 ◽

1993 ◽

Vol 71 (5) ◽

pp. 763-768 ◽

Cited By ~ 5

Author(s):

Min Chen ◽

R. Stephen Reid

Keyword(s):

Potentiometric Titration ◽

Ethylenediaminetetraacetic Acid ◽

Dissociation Constants ◽

Equilibrium Constants ◽

Acid Dissociation ◽

Equilibrium Models ◽

Acid Dissociation Constants ◽

Aqueous Sodium ◽

Ph Values ◽

Solution Speciation

Speciation in the aqueous sodium(I) – ethylenediaminetetraacetic acid and potassium(I) – ethylenediaminetetraacetic acid equilibrium systems was investigated by automated gravimetric potentiometric titration. It was found that in both cases, particularly below neutral pH values, speciation includes a previously uncharacterized diprotonated complex. All formation and acid dissociation constants were measured for the full systems. The validity of previous literature equilibrium constants, which are based on incomplete equilibrium models, is discussed.

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Axial coordination reactions with nitrogenous bases and determination of equilibrium constants for zinc tetraarylporphyrins containing four β,β′-fused butano and benzo groups in nonaqueous media

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424619500135 ◽

2019 ◽

Vol 23 (01n02) ◽

pp. 196-205 ◽

Cited By ~ 5

Author(s):

Lina Ye ◽

Yuanyuan Fang ◽

Zhongping Ou ◽

Liping Wang ◽

Songlin Xue ◽

...

Keyword(s):

Dissociation Constants ◽

Equilibrium Constants ◽

Acid Dissociation ◽

Nonaqueous Media ◽

Acid Dissociation Constants ◽

Axial Coordination ◽

Conjugate Acid ◽

Nitrogenous Base ◽

Spectral Titration

The axial coordination properties of six zinc tetraarylporphyrins with seven different nitrogenous bases were examined in CH2Cl2 for derivatives containing four [Formula: see text],[Formula: see text]-fused butano or benzo groups and the equilibrium constants (log[Formula: see text] determined using spectral titration methods. The examined compounds are represented as butano(YPh)4PorZn and benzo(YPh)4PorZn, where Por is the porphyrin dianion and Y is a CH3, H or Cl substituent on the para-position of each meso-phenyl ring of the macrocycle. The initial four-coordinate butano- and benzoporphyrins will axially bind one nitrogenous base to form five-coordinate derivatives in CH2Cl2 and this leads to a 4–22 nm red-shift of the Soret and Q bands. The log[Formula: see text] values range from 1.98 to 4.69 for butano(YPh)4PorZn and from 3.42 to 5.36 for benzo(YPh)4PorZn, with the exact value depending upon the meso and [Formula: see text]-substituents of the porphyrin and the conjugate acid dissociation constants (p[Formula: see text] of the nitrogenous base.

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