THE HYDROLYSIS OF ACETIC ANHYDRIDE IN WATER AND IN THE SYSTEM WATER: METHYL ETHYL KETONE

1950 ◽  
Vol 28b (11) ◽  
pp. 663-670
Author(s):  
E. N. Banks ◽  
A. E. Marshall ◽  
R. W. Vollett ◽  
R. R. McLaughlin
Keyword(s):  
Acetic Anhydride ◽  
Methyl Ethyl Ketone ◽  
Catalytic Effect ◽  
Methyl Ethyl ◽  
Initial Concentration ◽  
Velocity Constant ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Order Rate Equation ◽  
System Water

The rate of hydrolysis of acetic anhydride at 25 °C. in water (I), in solutions of methyl ethyl ketone (MEK) in water (II), and in solutions of water in MEK (III) have been studied. In I the observation of previous investigators that the velocity constant varies linearly with the initial concentration of acetic anhydride, but for any given initial concentration of acetic anhydride the reaction is pseudomonomolecular, was confirmed and extended. In II the velocity constant is lower than in I and decreases linearly with increasing concentration of MEK, but, again, the reaction is pseudomonomolecular for any given initial concentration of acetic anhydride. An equation and a nomogram that relate the velocity constant to the initial concentration of acetic anhydride, MEK, and water are presented. In III the second-order rate equation must be modified to compensate for the presumed catalytic effect of the hydrogen ion produced by hydrolysis.

Analysis of System Water-Benzene-Methyl Ethyl Ketone by High Frequency Oscillator

1951 ◽  
Vol 23 (11) ◽  
pp. 1625-1627 ◽  
Author(s):  
Philip West ◽  
Thomas Robichaux ◽  
T. S. Burkhalter
Keyword(s):  
Methyl Ethyl Ketone ◽  
High Frequency ◽  
Methyl Ethyl ◽  
High Frequency Oscillator ◽  
Frequency Oscillator ◽  
System Water

scholarly journals THE KINETICS OF TRYPSIN DIGESTION

1924 ◽  
Vol 6 (4) ◽  
pp. 429-437 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
High Temperature ◽  
Substrate Concentration ◽  
Trypsin Digestion ◽  
Velocity Constant ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

1. A study has been made of the rate of hydrolysis of concentrated gelatin solutions at a high temperature and with a large amount of trypsin. 2. Under these conditions the substrate concentration may be considered constant and the only variable is the decrease in the amount of trypsin owing to inactivation. 3. The theory based on the mass law predicts that under these conditions (a) the rate at any time will be proportional to the concentration of trypsin at that time; (b) the reaction should approximate a monomolecular one if the total hydrolysis observed is taken as the amount of substrate available; (c) that the velocity constant calculated in this way should agree with the constant for the decomposition of the enzyme and that it should be independent of the concentration of enzyme instead of proportional to it as is usually the case; and (d) that the total amount of substrate decomposed should be proportional to the amount of trypsin added at the beginning instead of independent of it. These results have been obtained experimentally.

Performance of Bismuth Oxide in the Cathaphoretic Epoxy Primers

2007 ◽  
Vol 544-545 ◽  
pp. 589-592
Author(s):  
Won Seog Yang ◽  
Seung Ho Ahn ◽  
Jun Sik Seo ◽  
Won Seung Cho ◽  
Jung Gu Kim ◽  
...  
Keyword(s):  
Methyl Ethyl Ketone ◽  
Bismuth Oxide ◽  
Corrosion Test ◽  
Catalytic Effect ◽  
Corrosion Property ◽  
Methyl Ethyl ◽  
Corrosion Properties ◽  
Cyclic Corrosion ◽  
Ft Ir

The anti-corrosion properties of and catalytic effect of crosslinking on Bi2O3 were investigated in this study. The results of double rubs test with methyl ethyl ketone, cyclic corrosion test and FT-IR with ATR show that Bi2O3 performs anti-corrosion property and catalytic effect of crosslinking of resin.

Effect of Nε-Alkylation of the Substrate on the Hydrolysis of Benzoylglycyl-L-Lysine by Carboxypeptidase B

1975 ◽  
Vol 53 (11) ◽  
pp. 1145-1149 ◽  
Author(s):  
Graham J. Moore ◽  
N. Leo Benoiton
Keyword(s):  
Aqueous Solution ◽  
Steric Hindrance ◽  
Alkyl Group ◽  
Side Chain ◽  
Methyl Ethyl ◽  
Reductive Methylation ◽  
Carboxypeptidase B ◽  
Substrate Side ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The action of carboxypeptidase B (EC 3.4.12.3) on the benzoylglycyl dipeptides Bz-Gly-Lys(X) where X = methyl, ethyl, propyl, formyl, dimethyl, isopropyl, trimethyl, and benzyl has been investigated. All were hydrolyzed, at a rate decreasing in the order indicated, except where X = trimethyl and benzyl. Compounds where X = dimethyl, formyl, and isopropyl were hydrolyzed very slowly, and did not inhibit the hydrolysis of Bz-Gly-Lys by the enzyme. The kinetic parameters kcat and Km were determined for compounds with X = methyl and ethyl. The observed decrease in rate of hydrolysis of substrates with increasing size of X is consistent with increasing steric hindrance effects arising from the interaction of the Nε-alkyl group with residues of the protein in the cleft which accommodates the substrate side-chain, and resulting in weaker binding of the substrate.Bz-Gly-Lys(Me2) was prepared by reductive methylation of Bz-Gly-Lys. Bz-Gly-Lys(Me3) was prepared by the reaction of Bz-Gly-Lys(Me2) with diazomethane in aqueous solution. Bz-Gly-Lys(Me) and Bz-Gly-Lys(Et) were synthesized by classical coupling procedures from the appropriately protected lysine derivatives.

REACTIONS OF SULPHONIC ESTERS: VI. THE TEMPERATURE DEPENDENCE OF THE RATE FOR THE HYDROLYSIS OF A SERIES OF ALKYL BENZENESULPHONATES

1957 ◽  
Vol 35 (7) ◽  
pp. 613-622 ◽  
Author(s):  
R. E. Robertson
Keyword(s):  
Transition State ◽  
Temperature Dependence ◽  
Methyl Ethyl ◽  
Temperature Dependent ◽  
Temperature Coefficients ◽  
Nucleophilic Displacement ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Data are presented showing temperature dependence of the rate of hydrolysis of methyl, ethyl, isopropyl, and n-propyl benzenesulphonates in water. The heat of activation is shown to be temperature dependent to the extent of −30 to −40 cal./mole deg. Since, in solvolysis, the properties of water favor ionization over nucleophilic displacement, it is suggested that these temperature coefficients, ΔCp‡, and the accompanying entropy differences, ΔS‡, can be rationalized in terms of variations in the reorganization of the solvent about the transition state.

Influence des composés organiques sur la vitesse d'apparition du complexe de transfert de charge 1Sn(II)—4Sn(IV) dans les bains acides d'étamage brillant

1978 ◽  
Vol 56 (20) ◽  
pp. 2624-2629 ◽  
Author(s):  
Gaston Verville
Keyword(s):  
Charge Transfer ◽  
Organic Compounds ◽  
Charge Transfer Complex ◽  
Sulphate Solution ◽  
Initial Concentration ◽  
Rate Of Hydrolysis ◽  
The Stability ◽  
Hydrolysis Of

The effect of a number of organic compounds on the rate of formation of 1Sn(II)–4Sn(IV) charge transfer complex in acidic stannous sulphate solutions and on the stability of these solutions has been determined by measuring, spectrophotometrically, the change of absorption of these solutions with time. From the results, it is possible to classify these organic compounds into three broad categories in terms of how they affect the formation of the charge transfer complex and the stability of the solution.These results have been interpreted taking into account that the formation of the 1Sn(II)–4Sn(IV) complex depends on the initial concentration of stannic ions present as an impurity in the stannous sulphate solution, the rate of oxidation of the stannous ions, the rate of hydrolysis of the stannic ions, and the stability of stannic colloids that are formed.

The Effects of Amines on the Esterase Activities of Thrombin and Thrombokinase and on Several Clotting Tests

1974 ◽  
Vol 31 (02) ◽  
pp. 309-318
Author(s):  
Phyllis S Roberts ◽  
Raphael M Ottenbrite ◽  
Patricia B Fleming ◽  
James Wigand
Keyword(s):  
Choline Chloride ◽  
Polymerization Process ◽  
Ammonium Bromide ◽  
Bovine Thrombin ◽  
One Stage ◽  
Human Proteins ◽  
Rate Of Hydrolysis ◽  
The One ◽  
Hydrolysis Of Esters ◽  
Hydrolysis Of

Summary1. Choline chloride, 0.1 M (in 0.25 M Tris. HCl buffer, pH 7.4 or 8.0, 37°), doubles the rate of hydrolysis of TAME by bovine thrombokinase but has no effect on the hydrolysis of this ester by either human or bovine thrombin. Only when 1.0 M or more choline chloride is present is the hydrolysis of BAME by thrombokinase or thrombin weakly inhibited. Evidence is presented that shows that these effects are due to the quaternary amine group.2. Tetramethyl ammonium bromide or chloride has about the same effects on the hydrolysis of esters by these enzymes as does choline chloride but tetra-ethyl, -n.propyl and -n.butyl ammonium bromides (0.1 M) are stronger accelerators of the thrombokinase-TAME reaction and they also accelerate, but to a lesser degree, the thrombin-TAME reaction. In addition, they inhibit the hydrolysis of BAME by both enzymes. Their effects on these reactions, however, do not follow any regular order. The tetraethyl compound is the strongest accelerator of the thrombokinase-TAME reaction but the tetra-ethyl and -butyl compounds are the strongest accelerators of the thrombin-TAME reaction. The ethyl and propyl compounds are the best (although weak) inhibitors of the thrombokinase-BAME and the propyl compound of the thrombin-BAME reactions.3. Tetra-methyl, -ethyl, -n.propyl and -n.butyl ammonium bromides (0.01 M) inhibit the clotting of fibrinogen by thrombin (bovine and human proteins) at pH 7.4, imidazole or pH 6.1, phosphate buffers and they also inhibit, but to a lesser degree, a modified one-stage prothrombin test. In all cases the inhibition increases regularly as the size of the alkyl group increases from methyl to butyl. Only the ethyl com pound (0.025 M but not 0.01 M), however, significantly inhibits the polymerization of bovine fibrin monomers. It was concluded that inhibition of the fibrinogen-thrombin and the one-stage tests by the quaternary amines is not due to any effect of the com pounds on the polymerization process but probably due to inhibition of thrombin’s action on fibrinogen by the quaternary amines.

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