Kinetic and equilibrium studies of the σ-adduct forming reactions of 1,3,5-trinitrobenzene and picryl chloride with some carbon bases

1986 ◽  
Vol 64 (9) ◽  
pp. 1714-1720 ◽  
Author(s):  
Michael R. Crampton ◽  
Terence P. Kee ◽  
Jennifer R. Wilcock
Keyword(s):  
Adduct Formation ◽  
Nucleophilic Attack ◽  
Initial Reaction ◽  
Equilibrium Studies ◽  
Equilibrium Data ◽  
Picryl Chloride ◽  
Ring Position

Reaction of 1,3,5-trinitrobenzene (TNB) with the malononitrile anion in methanol yields a carbon-bonded σ-adduct, (3). Ionisation of the remaining exocyclic hydrogen is favourable and yields the dianion (4). The initial reaction of 1-chloro-2,4,6-trinitrobenzene similarly occurs at an unsubstituted ring position, but is followed by slower nucleophilic attack at the 1-position yielding the substituted product. A major difference in the reaction of the ethyl malononitrile anion with TNB is that the adduct formed (11) has no readily dissociable proton. Hence, here, conversion to the carbon-bonded adduct is less favourable. Kinetic and equilibrium data are reported for these reactions and are compared with data for adduct formation involving methoxide ions.

scholarly journals Equilibrium, Kinetics, and Thermodynamics of the Removal of Nickel(II) from Aqueous Solution Using Cow Hooves

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
I. Osasona ◽  
O. O. Ajayi ◽  
A. O. Adebayo
Keyword(s):  
Aqueous Solution ◽  
Contact Time ◽  
Room Temperature ◽  
Physical Adsorption ◽  
Low Cost ◽  
Freundlich Isotherm ◽  
Isotherm Models ◽  
Order Kinetic ◽  
Equilibrium Studies ◽  
Equilibrium Data

The feasibility of using powdered cow hooves (CH) for removing Ni2+ from aqueous solution was investigated through batch studies. The study was conducted to determine the effect of pH, adsorbent dosage, contact time, adsorbent particle size, and temperature on the adsorption capacity of CH. Equilibrium studies were conducted using initial concentration of Ni2+ ranging from 15 to 100 mgL−1 at 208, 308, and 318 K, respectively. The results of our investigation at room temperature indicated that maximum adsorption of Ni2+ occurred at pH 7 and contact time of 20 minutes. The thermodynamics of the adsorption of Ni2+ onto CH showed that the process was spontaneous and endothermic. Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models were used to quantitatively analysed the equilibrium data. The equilibrium data were best fitted by Freundlich isotherm model, while the adsorption kinetics was well described by pseudo-second-order kinetic equation. The mean adsorption energy obtained from the D-R isotherm revealed that the adsorption process was dominated by physical adsorption. Powdered cow hooves could be utilized as a low-cost adsorbent at room temperature under the conditions of pH 7 and a contact time of 20 minutes for the removal of Ni(II) from aqueous solution.

Recommendations for measurement and presentation of biochemical equilibrium data

1976 ◽  
Vol 9 (3) ◽  
pp. 439-456 ◽  
Keyword(s):  
General Chemistry ◽  
Metal Ions ◽  
Marked Variation ◽  
Specific Enzyme ◽  
Experimental Conditions ◽  
Equilibrium Studies ◽  
Essential Information ◽  
Biochemical Systems ◽  
Equilibrium Data

Equilibrium data are of importance in describing and understanding of biochemical systems. At present there is marked variation among different investigators in the choice of experimental conditions for the study of similar or identical reactions and in the manner of reporting the data. In many cases the description of the system does not provide all the essential information that would permit reproduction of the experiments. This can lead to confusion and difficulties in correlating the results of different workers.Equilibrium studies in biochemistry involve special problems that are not encountered in general chemistry. The attainment of biochemical equilibria commonly involves the addition of a specific enzyme to the system to catalyse the reaction studied; sometimes two or more enzymes must be added. In addition the enzyme may require the presence of certain cofactors, such as metal ions. The reactants, or products, or both, may bind or release protons or other ions during the reaction under study.

Isothiazole chemistry. IV. Cyanide cleavage of the S-N bond in 3-hydroxyisothiazole

1967 ◽  
Vol 20 (12) ◽  
pp. 2729 ◽  
Author(s):  
WD Crow ◽  
I Gosney
Keyword(s):  
Equilibrium Constant ◽  
Rate Constants ◽  
Nucleophilic Attack ◽  
Effect Of Temperature ◽  
Cyanide Ion ◽  
Equilibrium Studies ◽  
Conjugate Acid ◽  
Ph Range ◽  
Rate Profile ◽  
Direct Attack

Nucleophilic attack on 3-hydroxyisothiazole by cyanide ion, yielding cis-3-thiocyanoacrylamide, has been investigated over the pH range 0.00-5.50. Rate constants have been measured both for direct attack by cyanide ion and from the effect of cyanide ion in retarding the cyclization of the thiocyanoacrylamide; in both cases the derived rate constants agree. The pH-rate profile of the reaction reveals the existence of two kinetically discrete mechanisms. Within the range 5.50-4.00 the dominating mechanism is one involving a slow direct attack on 3-hydroxyisothiazole itself, while at pH less than 3.50 the conjugate acid of this molecule is subjected to a much faster attack. Equilibrium studies have been made for the system, and the effect of temperature on the equilibrium constant has been used to derive thermodynamic parameters.

scholarly journals Bromofatty aldehyde derived from bromine exposure and myeloperoxidase and eosinophil peroxidase modify GSH and protein

2018 ◽  
Vol 59 (4) ◽  
pp. 696-705 ◽  
Author(s):  
Mark A. Duerr ◽  
Elisa N. D. Palladino ◽  
Celine L. Hartman ◽  
James A. Lambert ◽  
Jacob D. Franke ◽  
...  
Keyword(s):  
Phorbol Myristate Acetate ◽  
Plasma Levels ◽  
Adduct Formation ◽  
Nucleophilic Attack ◽  
Fatty Aldehyde ◽  
Myristate Acetate ◽  
Protein Adduct ◽  
Protein Thiols ◽  
Hypobromous Acid ◽  
Activated Neutrophils

α-Chlorofatty aldehydes (α-ClFALDs) and α-bromofatty aldehydes (α-BrFALDs) are produced in activated neutrophils and eosinophils. This study investigated the ability of α-BrFALD and α-ClFALD to react with the thiols of GSH and protein cysteinyl residues. Initial studies showed that 2-bromohexadecanal (2-BrHDA) and 2-chlorohexadecanal (2-ClHDA) react with GSH producing the same fatty aldehyde-GSH adduct (FALD-GSH). In both synthetic and cellular reactions, FALD-GSH production was more robust with 2-BrHDA compared with 2-ClHDA as precursor. NaBr-supplemented phorbol myristate acetate (PMA)-activated neutrophils formed more α-BrFALD and FALD-GSH compared with non-NaBr-supplemented neutrophils. Primary human eosinophils, which preferentially produce hypobromous acid and α-BrFALD, accumulated FALD-GSH following PMA stimulation. Mice exposed to Br2 gas had increased levels of both α-BrFALD and FALD-GSH in the lungs, as well as elevated systemic plasma levels of FALD-GSH in comparison to mice exposed to air. Similar relative reactivity of α-ClFALD and α-BrFALD with protein thiols was shown using click analogs of these aldehydes. Collectively, these data demonstrate that GSH and protein adduct formation are much greater as a result of nucleophilic attack of cysteinyl residues on α-BrFALD compared with α-ClFALD, which was observed in both primary leukocytes and in mice exposed to bromine gas.

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