Kinetics of the Acid Catalysis of the Hydration of Fumaric Acid to Malic Acid

1957 ◽  
Vol 61 (12) ◽  
pp. 1637-1640 ◽  
Author(s):  
Lee T. Rozelle ◽  
Robert A. Alberty
Keyword(s):  
Fumaric Acid ◽  
Malic Acid ◽  
Acid Catalysis ◽  
Kinetics Of

Kinetics and mechanism of cyclization of N-(2-methoxycarbonylphenyl)-N’-methylsulphonamide to 3-methyl-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide

1991 ◽  
Vol 56 (8) ◽  
pp. 1701-1710 ◽  
Author(s):  
Jaromír Kaválek ◽  
Vladimír Macháček ◽  
Miloš Sedlák ◽  
Vojeslav Štěrba
Keyword(s):  
Potassium Hydroxide ◽  
Acid Catalysis ◽  
Potassium Hydroxide Solution ◽  
Hydroxide Solution ◽  
General Base ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Cyclization Kinetics ◽  
Rate Limiting ◽  
Kinetics Of

The cyclization kinetics of N-(2-methylcarbonylphenyl)-N’-methylsulfonamide (IIb) into 3-methyl-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide (Ib) has been studied in ethanolamine, morpholine, and butylamine buffers and in potassium hydroxide solution. The cyclization is subject to general base and general acid catalysis. The value of the Bronsted coefficient β is about 0.1, which indicates that splitting off of the proton from negatively charged tetrahedral intermediate represents the rate-limiting and thermodynamically favourable step. In the solutions of potassium hydroxide the cyclization of dianion of the starting ester IIb probably becomes the rate-limiting step.

scholarly journals Adsorption of malic acid at the hydroxyapatite/aqueous NaCl solution interface

2021 ◽  
Author(s):  
Władysław Janusz ◽  
Ewa Skwarek
Keyword(s):  
Zeta Potential ◽  
Malic Acid ◽  
Particle Sizes ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
Radioisotope Method ◽  
X Ray ◽  
Solution Interface ◽  
Adsorption Desorption ◽  
Kinetics Of

AbstractThe aim of the study was the basic incidence on the phenomenon of adsorption that occurs at the hydroxyapatite/malic acid interface, leading to a change in the surface properties of hydroxyapatite, Analytical methods used in the research: X-ray diffraction (XRD) as well as by the, adsorption–desorption of nitrogen (ASAP), potentiometric titration. The specific adsorption of malic acid ions at the hydroxyapatite interface was investigated by means of the radioisotope method. The zeta potential of hydroxyapatite dispersions was determined by electrophoresis with Zetasizer Nano ZS90 by Malvern. The particle sizes of hydroxyapatite samples were analyzed using Masteriszer 2000 Malvern. Studies on the kinetics of malic acid on hydroxyapatite from a solution with an initial concentration of 1 mmol/dm3 have shown that the adsorption process is initially fast, followed by a slow adsorption step. An increase in the pH of the solution causes a decrease in the malic acid adsorption as a result of competition with hydroxyl ions. The presence of adsorbed malic acid was confirmed by the FTIR measurements. The effect of malic acid adsorption on the zeta potential and particle size distribution of hydroxyapatite in the NaCl solution was investigated.

Simultaneous Gas Chromatographic Determination of Carboxylic Acids in Soft Drinks and Jams

1985 ◽  
Vol 68 (5) ◽  
pp. 902-905
Author(s):  
Taizo Tsuda ◽  
Hiroshi Nakanishi ◽  
Takashi Morita ◽  
Junko Takebayashi
Keyword(s):  
Benzoic Acid ◽  
Succinic Acid ◽  
Tartaric Acid ◽  
Carboxylic Acids ◽  
Fumaric Acid ◽  
Malic Acid ◽  
Sorbic Acid ◽  
Chromatographic Determination ◽  
Dehydroacetic Acid

Abstract A method was developed for simultaneous gas chromatographic determination of sorbic acid, dehydroacetic acid, and benzoic acid used as preservatives, and succinic acid, fumaric acid, malic acid, and tartaric acid used as acidulants in soft drinks and jams. A sample was dissolved in NH4OH-NH4CI pH 9 buffer solution, and an aliquot of the solution was passed through a QAE-Sephadex A 25 column. The column was washed with water, and the carboxylic acids were eluted with 0.1N HC1. Sorbic acid, dehydroacetic acid, and benzoic acid were extracted with ethyl ether-petroleum ether (1 + 1), and determined on a 5% DEGS + 1% H3PO4 column. Succinic acid, fumaric acid, malic acid, and tartaric acid in the lower layer were derivatized with N,0- bis(trimethylsilyl)acetamide and trimethylchlorosilane, and determined on a 3% SE-30 column. Recoveries from soft drink and jam samples fortified with 0.1% each of 7 carboxylic acids ranged from 92.4 to 102.6% for preservatives, and from 88.1 to 103.2% for acidulants.

Mechanochemical synthesis, characterization, and thermal behavior of meloxicam cocrystals with salicylic acid, fumaric acid, and malic acid

2019 ◽  
Vol 138 (1) ◽  
pp. 765-777 ◽  
Author(s):  
Richard Perosa Fernandes ◽  
André Luiz Carneiro Soares do Nascimento ◽  
Ana Carina Sobral Carvalho ◽  
José Augusto Teixeira ◽  
Massao Ionashiro ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Thermal Behavior ◽  
Mechanochemical Synthesis ◽  
Fumaric Acid ◽  
Malic Acid

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.

Sign in / Sign up

Export Citation Format

Share Document