The .alpha.-cyano-.alpha.-phenylacetic acid keto-enol system. Flash photolytic generation of the enol in aqueous solution and determination of the keto-enol equilibrium constants and acid dissociation constants interrelating all keto and enol forms in that medium

1994 ◽  
Vol 116 (1) ◽  
pp. 73-81 ◽  
Author(s):  
J. Andraos ◽  
Y. Chiang ◽  
A. J. Kresge ◽  
I. G. Pojarlieff ◽  
N. P. Schepp ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Phenylacetic Acid ◽  
Dissociation Constants ◽  
Equilibrium Constants ◽  
Acid Dissociation ◽  
Acid Dissociation Constants

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

2009 ◽  
Vol 13 (08n09) ◽  
pp. 849-853 ◽  
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+ .

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

2019 ◽  
Vol 23 (01n02) ◽  
pp. 196-205 ◽  
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.

ChemInform Abstract: Determination of the Acid Dissociation Constants for Some Mycotoxins of the Alternaria alternata genus.

ChemInform ◽  
2010 ◽  
Vol 29 (52) ◽  
pp. no-no
Author(s):  
P. G. MOLINA ◽  
M. A. ZON ◽  
H. FERNANDEZ
Keyword(s):  
Alternaria Alternata ◽  
Dissociation Constants ◽  
Acid Dissociation ◽  
Acid Dissociation Constants

Novel 1,4-naphthoquinone N-aroylthioureas: Syntheses, crystal structure, anion recognition properties, DFT studies and determination of acid dissociation constants

2018 ◽  
Vol 269 ◽  
pp. 920-932 ◽  
Author(s):  
Müge Gemili ◽  
Yahya Nural ◽  
Ergin Keleş ◽  
Burcu Aydıner ◽  
Nurgül Seferoğlu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Dissociation Constants ◽  
Anion Recognition ◽  
Acid Dissociation ◽  
Dft Studies ◽  
Acid Dissociation Constants
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