Rates of hydrolysis of a monochlorotriazine dye in presence of non-ionic surfactant

1968 ◽  
Vol 21 (4) ◽  
pp. 1007 ◽  
Author(s):  
BR Craven ◽  
A Datyner ◽  
TP Doyle
Keyword(s):  
Complex Formation ◽  
Ethylene Oxide ◽  
Rate Constant ◽  
The Other ◽  
Ionic Surfactant ◽  
A Value ◽  
Surfactant Complex ◽  
Rate Of Hydrolysis ◽  
Ethylene Oxide Chain ◽  
Hydrolysis Of

The presence of nonylphenol-poly(oxyethylene) surfactant decreases the rate constant for the hydrolysis of a monochlorotriazine dye, the effect being enhanced by increasing the surfactant to dye ratio and diminishing by increasing the temperature. At 80� and 100�, the longer the ethylene oxide chain length of a surfactant the more effective it is in reducing the rate constant. At 60�, however, all of the surfactants used appear to be equally effective. At 80� and 100�, extrapolation of rate constants to zero surfactant to dye ratio gives a value very close to the rate constant in the absence of surfactant, but at 60� the rate constant for NPl0 extrapolated to zero surfactant to dye ratio is close to the value from the surfactant-free run, but values obtained with the other surfactants are much higher and similar to that obtained in presence of a polyether glycol. It is suggested that this anomaly is due to the initial aggregation of the dye at 60� so that the addition of small quantities of surfactant other than NPl0 causes initial disaggregation and an increase in the rate of hydrolysis. Further increases in the amount of surfactant cause dye-surfactant complex formation which produces a decrease in the rate of hydrolysis.

pH Effects in trypsin catalysis

1969 ◽  
Vol 47 (21) ◽  
pp. 4021-4029 ◽  
Author(s):  
H. P. Kasserra ◽  
K. J. Laidler
Keyword(s):  
Complex Formation ◽  
Ph Dependence ◽  
Specific Rotation ◽  
Ph Effects ◽  
Ph Values ◽  
A Value ◽  
Available Information ◽  
Hydrolysis Of ◽  
Substrate Concentrations ◽  
Covalent Complex

A kinetic study has been made of the trypsin-catalyzed hydrolysis of N-benzoyl-L-alanine methyl ester, at pH values ranging from 6 to 10. The substrate concentrations varied from 1.7 × 10−3 to 4.3 × 10−2 M. From the rates were calculated, at each pH, values of [Formula: see text] (corresponding to [Formula: see text]), [Formula: see text] (corresponding to [Formula: see text]) and [Formula: see text] The specific levorotation of trypsin was measured and found to vary with pH in the pH region 5–11, the change in specific rotation following the ionization of a single group with pK(app) of 9.4. At pH 11 the specific rotation of trypsin, its zymogen, and its phosphorylated derivative were approximately the same, suggesting similar conformations for all three forms of the protein.The kinetic results on the acid side were very similar to those obtained by other investigators for chymotrypsin; they imply that there is a group of [Formula: see text] in the free enzyme, presumably the imidazole function of a histidine residue, and that this group is involved in acylation and deacylation, which can only occur if it is unprotonated. The behavior on the basic side was found to be different from that with chymotrypsin revealing a decrease in [Formula: see text] at high pH corresponding to a value of [Formula: see text] whereas [Formula: see text] showed sigmoid pH-dependence. An interpretation of these results that is consistent with all available information is that a group of [Formula: see text] (presumably the —NH3+ function of the terminal isoleucine) controls the conformation and thereby the activity of the enzyme at different stages of complex formation. In contrast to chymotrypsin, the pK of this ionizing group appears to be generally lowered by covalent complex formation between trypsin and its substrates.

THE CHEMISTRY OF ETHYLENE OXIDE: V. THE REACTION OF ETHYLENE OXIDE WITH HALIDE IONS IN NEUTRAL AND ACID SOLUTION

1952 ◽  
Vol 30 (3) ◽  
pp. 169-176 ◽  
Author(s):  
A. M. Eastham ◽  
G. A. Latremouille
Keyword(s):  
Aqueous Solution ◽  
Ethylene Oxide ◽  
Acid Solution ◽  
Activation Energies ◽  
Hydrogen Halide ◽  
Halide Ions ◽  
Neutral Aqueous Solution ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The rates of reaction of halide ions with ethylene oxide in neutral aqueous solution and the rate of hydrolysis of ethylene oxide in acid solution have been measured and the activation energies determined. From these data and from the ratio of glycol to chlorohydrin formed when ethylene oxide reacts with excess aqueous hydrogen halide, the rates of the acid-catalyzed addition of halide ions to ethylene oxide at 25 °C. have been estimated.

scholarly journals Degradation of connective tissue matrices by macrophages. II. Influence of matrix composition on proteolysis of glycoproteins, elastin, and collagen by macrophages in culture.

1980 ◽  
Vol 152 (6) ◽  
pp. 1527-1536 ◽  
Author(s):  
P A Jones ◽  
Z Werb
Keyword(s):  
Connective Tissue ◽  
Peritoneal Macrophages ◽  
The Other ◽  
Matrix Proteins ◽  
Matrix Composition ◽  
Disease States ◽  
The Matrix ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Mouse Peritoneal Macrophages

Thioglycollate-elicited mouse peritoneal macrophages were cultured in contact with the mixture of extracellular matrix proteins produced by rat smooth muscle cells in culture. Both live macrophages and their conditioned media hydrolyzed glycoproteins, elastin, and collagen. Live macrophages also degraded extracellular connective tissue proteins secreted by endothelial cells and fibroblasts. The glycoproteins in the matrix markedly inhibited the rate of digestion of the other macromolecules, particularly elastin. When plasminogen was added to the matrix, activation of plasminogen to plasmin resulted in the hydrolysis of the glycoprotein components, which then allowed the macrophage elastase easier access to its substrate, elastin. Thus, although plasmin has no direct elastinolytic activity, its presence accelerated the rate of hydrolysis of elastin and therefore the rate of matrix degradation. These findings may be important in an understanding of disease states, such as emphysema and atherosclerosis, that are characterized by the destruction of connective tissue.

Die γ-Radiolyse und Pulsradiolyse des Schwefelkohlenstoffs in wäßriger Lösung / The γ-Radiolysis and Pulse Radiolysis of Carbon Disulfide in Aqueous Solution

1973 ◽  
Vol 28 (1-2) ◽  
pp. 12-22 ◽  
Author(s):  
W. Roebke ◽  
M. Schöneshöfer ◽  
A. Henglein
Keyword(s):  
Rate Constant ◽  
Carbon Disulfide ◽  
Second Order ◽  
Γ Irradiation ◽  
Electrolytic Dissociation ◽  
First Order ◽  
A Value ◽  
Diffusion Controlled ◽  
Polymer Pyrolysis ◽  
Hydrolysis Of

A polymer (CHS2)n and sulfate are formed in the γ-irradiation of deaerated aqueous carbon disulfide solutions. The G-values are 3.6 and 0.41, respectively. In the presence of N,O, G (polymer) is decreased while G(SO4-) is increased. G(SO4-) can be decreased by isopropanol. G(polymer) is increased by H+ ions and reaches a value of 5 below pH = 2. Formic acid, hydrogen sulfide and carbonate are formed in the hydrolysis of the polymer. Pyrolysis at first leads to a red oil consisting of oligomer (HCS2)n and finally to H2S, CS2 plus a residue containing much carbon. The structure of the polymer is discussed.Pulse radiolytic experiments show that CS2 reacts with eaq (3.1 × 1010M-1s-1) and OH(7.4 × 109M-1s-1) in a diffusion controlled manner. The first product of the reaction with OH is SC(OH)S. The pK of the electrolytic dissociationSC(OH)Ṣ ⇄ SC(O-)S + H+is 4.4. The absorption spectra of SC(OH)S and SC(O-)S were measured. SC(OH)S disappears by second order with 2k = 1.6 × 109M-1s-1 at pH = 6. The product is a bivalent acid, the spectrum of which was measured. The second pK of this acid is 5.7, its first pK is lower than 4.Both eāq and H react with CS2 to form SCS-. The absorption spectrum of this radical anion was measured. The pK of the equilibriumSCSH ⇄SCS- + H+is about 1.6. In solutions of low H+-concentration, SCS- disappears by second order with 2k = 6.4 × 109M-1s-1. The structure of dithioformic acid is attributed to the resulting product. In solutions of high H+-concentration, SCS- (or SCSH) disappears by a fast first order process, the rate constant of which increases with H+-concentration. The carbeniat neutralizationis believed to be responsible for this process. The rate constant is 5.1 × 107M-1S-1. The spectrum of SC(H)S was measured. This radical disappears by second order with 2k = 7.4 × 109M-1s-1. The spectrum of the resulting product was also determined.It is concluded that the formation of the polymer and of SO4- occurs in processes in which the first products from the attack of eāq, H and OH on CS2 as well as molecules which were built up from these products are involved.

scholarly journals Inclusion of the insecticide fenitrothion in dimethylated-β-cyclodextrin: unusual guest disorder in the solid state and efficient retardation of the hydrolysis rate of the complexed guest in alkaline solution

2013 ◽  
Vol 9 ◽  
pp. 106-117 ◽  
Author(s):  
Dyanne L Cruickshank ◽  
Natalia M Rougier ◽  
Raquel V Vico ◽  
Susan A Bourne ◽  
Elba I Buján ◽  
...  
Keyword(s):  
Kinetic Studies ◽  
The Other ◽  
Hydrolysis Rate ◽  
Crystalline Inclusion ◽  
X Ray Diffraction ◽  
X Ray ◽  
A Value ◽  
Host Compound ◽  
Hydrolysis Of ◽  
Remarkable Reduction

An anhydrous 1:1 crystalline inclusion complex between the organophosphorus insecticide fenitrothion [O,O-dimethyl O-(3-methyl-4-nitrophenyl)phosphorothioate] and the host compound heptakis(2,6-di-O-methyl)-β-cyclodextrin (DIMEB) was prepared and its structure elucidated by single-crystal X-ray diffraction. This revealed two independent host molecules in the asymmetric unit. In one of these, the cavity is occupied by two disordered guest components (distinguishable as rotamers with respect to the P–OAr bond) while in the other, three distinct guest components with site-occupancies 0.44, 0.29 and 0.27 appear, the last having a reversed orientation relative to all the other components. Kinetic studies of the alkaline hydrolysis of fenitrothion in the presence of DIMEB showed a remarkable reduction of 84% in the rate of this reaction relative to that for the free substrate, a value exceeding those previously attained with the native hosts, β- and γ-cyclodextrin, and fully methylated β-cyclodextrin.

Ethanol fermentation of enzymatically hydrolysed pretreated wood fractions using Trichoderma cellulases, Zymomonas mobilis, and Saccharomyces cerevisiae

1982 ◽  
Vol 28 (12) ◽  
pp. 1311-1319 ◽  
Author(s):  
J. N. Saddler ◽  
C. Hogan ◽  
M. K.-H. Chan ◽  
G. Louis-Seize
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cultures ◽  
Ethanol Fermentation ◽  
Zymomonas Mobilis ◽  
Protein A ◽  
A Value ◽  
Culture Filtrates ◽  
Rate Of Hydrolysis ◽  
Pretreatment Conditions ◽  
Hydrolysis Of

Several highly cellulolytic fungi were initially screened for their cellulase and β-glucosidase activities. Culture filtrates from Trichoderma E58 demonstrated the highest β-glucosidase activity, giving a value of 1.0 IU/mg protein. A variety of different cellulose and pretreated wood substrates were hydrolysed by various cellulase preparations. The importance of the pretreatment conditions and ensuing chemical extractions of the cellulosic substrates was demonstrated by the range of sugar and ethanol values obtained after saccharification and fermentation of the liberated sugars. The rate of hydrolysis of the cellulosic substrate by Trichoderma E58 culture filtrates, concentrated culture filtrates, and whole cell cultures was compared. An ethanol value of 2.2% (w/v) could be obtained after hydrolysis of 5% Solka floe by concentrated culture filtrates of Trichoderma E58 and fermentation of the liberated sugars by Zymomonas mobilis or Saccharomyces cerevisiae.

scholarly journals Stopped-Flow Kinetic Study of Reduction of Ferric Maltol Complex by Ascorbate

2016 ◽  
Vol 12 (4) ◽  
pp. 4338-4341
Author(s):  
Shabana Amin ◽  
Shazia Nisar ◽  
S Arif Kazmi
Keyword(s):  
Kinetic Study ◽  
Acid Hydrolysis ◽  
Rate Constant ◽  
Free Ligand ◽  
Low Ph ◽  
Reducing Agent ◽  
The Other ◽  
Stopped Flow ◽  
Kinetic Investigation ◽  
Hydrolysis Of

Stopped-flow kinetic investigation of reduction of Fe(III)-maltol complex is reported. The rates are dependent on pH in a complex way. On one hand at low pH there is a predominance of Fe(III)(maltol)2 which is easier to reduce compared to Fe(III) (maltol)3 which is more resistant to reduction. On the other hand ascorbate is a stronger reducing agent at higher pH. The rates are also found to be inversely dependent on the concentration of free ligand. These observations are explained by the following rate law:Rate = ((k0 +k1[H+])k2 [Asc-]/ (k-1[HMal] + k2[Asc-])) + k3 [Asc-] ) [FeIII(Mal)3] Here k1 is the rate constant for acid hydrolysis of the Fe(maltol)3 complex to Fe(maltol)2 complex and is directly controlled by H+, k0 is the rate constant for hydrolysis of the Fe(maltol)3 complex to Fe(maltol)2 complex and is an intrinsic process, k-1 is the rate constant of reformation of the tris complex by reaction of the bis complex and the free ligand, k2 is the rate constant for reduction of the bis complex by ascorbate and k3 is the rate constant for the reduction of the tris complex by ascorbate.

Kinetic medium effects. IV. Hydrolysis of trimethyl phosphate in mixed solvents

1970 ◽  
Vol 23 (2) ◽  
pp. 297 ◽  
Author(s):  
PT McTigue ◽  
PV Renowden
Keyword(s):  
Water Content ◽  
Rate Constant ◽  
Isotope Effects ◽  
Mixed Solvents ◽  
Trimethyl Phosphate ◽  
Spontaneous Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Acid Catalysed Reactions ◽  
Solvent Isotope ◽  
Hydrolysis Of

The rate of hydrolysis of trimethyl phosphate (tmp) has been measured at 90.5� as a function of solvent composition in water-dimethyl sulphoxide and water-ethylene glycol mixtures. The rate constant of the "spontaneous" hydrolysis decreases with decreasing water content; an acid-catalysed reaction, whose rate constant increases with decreasing water content, becomes dominant at low water concentrations. Solvent isotope effects in D2O have been measured for both the spontaneous and acid-catalysed reactions, and are close to unity in each case. Salt effects have also been studied In aqueous sodium nitrate and perchlorate solutions, and are found to be small. Reaction mechanisms are discussed in the light of the results obtained.

CONJUGATED OESTROGENS. III

1963 ◽  
Vol 43 (3) ◽  
pp. 375-386 ◽  
Author(s):  
Robert M. Nakamura ◽  
Stanley Kushinsky
Keyword(s):  
Enzymatic Hydrolysis ◽  
Postmenopausal Women ◽  
Intravenous Injection ◽  
Rate Constant ◽  
Human Urine ◽  
Order Rate Constant ◽  
The Other ◽  
Relative Distribution ◽  
First Order ◽  
Hydrolysis Of

ABSTRACT The enzymatic hydrolysis (β-glucuronidase) of conjugated oestrogens in human urine has been studied. The urine was collected from postmenopausal women who had received oestradiol-4-14C by intravenous injection. Hydrolysis was carried out for different periods of time and with various concentrations of enzyme and the relative distribution of several hydrolyzed oestrogens determined under these conditions. The oestrogens reported are: 2-methoxyoestrone, oestrone, oestradiol, ketols (16α-hydroxyoestrone plus 16-ketooestradiol), epioestriol and oestriol. The first order rate constant for oestrone was particularly high in comparison with those of the other oestrogens. Two plateaus were observed on the curves of the hydrolysis of several oestrogens (ketols, epioestriol and oestriol) when plotted as a function of time, possibly as a result of multiple conjugation of these oestrogens.

THE OXIDATION OF MANGANATE BY PERIODATE

1960 ◽  
Vol 38 (12) ◽  
pp. 2342-2348 ◽  
Author(s):  
M. W. Lister ◽  
Y. Yoshino
Keyword(s):  
Activation Energy ◽  
Reaction Mechanism ◽  
Rate Constant ◽  
Alkaline Solution ◽  
Ionization Constant ◽  
Main Reaction ◽  
Partial Hydrolysis ◽  
A Value ◽  
Hydrolysis Of

The reaction between periodate and manganate ions in alkaline solution has been examined, and at 35 °C the rate is given by the equation, time being measured in minutes,[Formula: see text]It is proposed that the main reaction mechanism is[Formula: see text][Formula: see text]Hence k1 = 107 (g-molecule/l.)−1 min−1 at 35 °C, and it was found that the activation energy is about 13.9 kcal/g-molecule. Data of Carrington and Symonds (2), combined with the value for k1, make k2 = 2.8 × 106 (g-molecule/l.)−1 min−1. Added permanganate ions slow up the reaction; this is ascribed to the reverse of reaction (i) competing with reaction (ii). This gives a value for k3 of 2 × 107 (g-molecule/l.)−1 min−1; this is so large a rate constant as to make it probable that the hypomanganate ions are hydrolyzed. The effect of hydroxide concentration on the rate is ascribed to partial hydrolysis of manganate ions. The observed results would require the ionization constant of HMnO4− to be 7 × 10−11.

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