Kinetics of the hydrolysis of the dichromate ion. V. General acid catalysis

1969 ◽  
Vol 73 (12) ◽  
pp. 4391-4394 ◽  
Author(s):  
R. Baharad ◽  
Berta Perlmutter-Hayman ◽  
Michael A. Wolff
Keyword(s):  
Acid Catalysis ◽  
General Acid ◽  
Kinetics Of ◽  
Hydrolysis Of

Efficient intramolecular general acid catalysis of the hydrolysis of a dialkyl acetal

1996 ◽  
pp. 2355 ◽  
Author(s):  
Christopher J. Brown ◽  
Anthony J. Kirby
Keyword(s):  
Acid Catalysis ◽  
General Acid ◽  
Hydrolysis Of

General acid catalysis of ketal hydrolysis. The hydrolysis of tropone diethyl ketal

1969 ◽  
Vol 91 (25) ◽  
pp. 7163-7166 ◽  
Author(s):  
Edwin Anderson ◽  
Thomas H. Fife
Keyword(s):  
Acid Catalysis ◽  
General Acid ◽  
Hydrolysis Of

Reaction kinetics of 1,2-diaminobenzene with ethyl 2-oxopropanoate and 2,3-butanedione

1988 ◽  
Vol 53 (12) ◽  
pp. 3154-3163 ◽  
Author(s):  
Jiří Klicnar ◽  
Jaromír Mindl ◽  
Ivana Obořilová ◽  
Jaroslav Petříček ◽  
Vojeslav Štěrba
Keyword(s):  
Reaction Kinetics ◽  
Acid Catalysis ◽  
Reaction Pathway ◽  
Hydroxide Ion ◽  
Tetrahedral Intermediate ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
General Acid ◽  
Rate Limiting ◽  
Kinetics Of

The reaction of 1,2-diaminobenzene with 2,3-butanedione is subject to general acid catalysis in acetate and phosphate buffers (pH 4-7). The rate-limiting step of formation of 2,3-dimethylquinoxaline consists in the protonation of dipolar tetrahedral intermediate. In the case of the reaction of 1,2-diaminobenzene with ethyl 2-oxopropanoate, the dehydration of carbinolamine gradually becomes rate-limiting with increasing pH in acetate buffers, whereas in phosphate buffers a new reaction pathway makes itself felt, viz. the formation of amide catalyzed by the basic buffer component and by hydroxide ion.

General acid catalysis in the hydrolysis of benzo[a]pyrene 7,8-diol 9,10-epoxides

1979 ◽  
Vol 101 (17) ◽  
pp. 5086-5088 ◽  
Author(s):  
Dale L. Whalen ◽  
Angela M. Ross ◽  
Jean A. Montemarano ◽  
Dhiren R. Thakker ◽  
Harukiko Yagi ◽  
...  
Keyword(s):  
Acid Catalysis ◽  
General Acid ◽  
Hydrolysis Of

General acid catalysis and the pH-independent hydrolysis of 2-(p-nitrophenoxy) tetrahydropyran

1970 ◽  
Vol 92 (6) ◽  
pp. 1681-1684 ◽  
Author(s):  
Thomas H. Fife ◽  
Lily H. Brod
Keyword(s):  
Acid Catalysis ◽  
General Acid ◽  
Hydrolysis Of

scholarly journals pH-dependence and structure–activity relationships in the papain-catalysed hydrolysis of anilides

1971 ◽  
Vol 124 (1) ◽  
pp. 117-122 ◽  
Author(s):  
G. Lowe ◽  
Y. Yuthavong
Keyword(s):  
Acid Catalysis ◽  
Ph Dependence ◽  
Base Catalysis ◽  
General Base ◽  
Structure Activity ◽  
Equilibrium Binding ◽  
General Acid ◽  
Leaving Group ◽  
Hydrolysis Of ◽  
Equilibrium Binding Constant

The pH-dependence of the Michaelis–Menten parameters for the papain-catalysed hydrolysis of N-acetyl-l-phenylalanylglycine p-nitroanilide was determined. The equilibrium binding constant, Ks, is independent of pH between 3.7 and 9.3, whereas the acylation constant, k+2, shows bell-shaped pH-dependence with apparent pKa values of 4.2 and 8.2. The effect of substituents in the leaving group on the acylation constant of the papain-catalysed hydrolysis of hippuryl anilides and N-acetyl-l-phenylalanylglycine anilides gives rise in both series to a Hammett ρ value of -1.04. This indicates that the enzyme provides electrophilic, probably general-acid, catalysis, as well as the nucleophilic or general-base catalysis previously found. A mechanism involving a tetrahedral intermediate whose formation is general-base-catalysed and whose breakdown is general-acid-catalysed seems most likely. The similarity of the Hammett ρ values appears to exclude facilitated proton transfer as a means through which the specificity of papain is expressed.

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