Transition states for the hydrolysis of 4-nitroacetanilide and 4-nitrothioacetanilide in varying concentrations of sulfuric acid

1978 ◽  
Vol 100 (22) ◽  
pp. 7023-7027 ◽  
Author(s):  
John T. Edward ◽  
Gary D. Derdall ◽  
Sin Cheong Wong
Keyword(s):  
Sulfuric Acid ◽  
Transition States ◽  
Hydrolysis Of

The hydrolysis of thioacetic, thiobenzoic, and three substituted thiobenzoic acids in perchloric and sulfuric acids

1978 ◽  
Vol 56 (7) ◽  
pp. 935-940 ◽  
Author(s):  
John T. Edward ◽  
Graeme Welch ◽  
Sin Cheong Wong
Keyword(s):  
Sulfuric Acid ◽  
Activity Coefficients ◽  
Acid Concentration ◽  
Perchloric Acid ◽  
Transition States ◽  
Sulfuric Acid Concentration ◽  
Thiobenzoic Acid ◽  
The Difference ◽  
Different Response ◽  
Hydrolysis Of

The rates of hydrolysis of thioacetic, thiobenzoic, and three substituted thiobenzoic acids increase with concentration of solvent sulfuric or perchloric acid to a maximum in 30–40% acid and then decrease. Yates–McClelland r, Bunnett–Olsen [Formula: see text], and Hammett ρ parameters, and entropies of activation indicate an AAC2 mechanism over this range of acid concentrations. In acid concentrations above 50–60% the rates increase sharply and the same mechanistic criteria now indicate an AAc1 mechanism. The difference between the rate–acidity profile of thiobenzoic acid and that of ethyl thiolbenzoate can be explained by the different response of the activity coefficients of their transition states to increase in sulfuric acid concentration.

Studies of azo and azoxy dyestuffs. Part 18. Kinetics and mechanism of the hydrolysis of 3- and 4-(p′-methoxyphenylazo)pyridines in aqueous sulfuric acid media

1986 ◽  
Vol 64 (11) ◽  
pp. 2115-2126 ◽  
Author(s):  
Erwin Buncel ◽  
Ikenna Onyido
Keyword(s):  
Sulfuric Acid ◽  
Transition States ◽  
Activation Parameters ◽  
Nucleophilic Attack ◽  
Acid Solutions ◽  
Acid Media ◽  
Charge Delocalization ◽  
Leaving Group ◽  
The Difference ◽  
Hydrolysis Of

The kinetics of hydrolysis of 4-(p′-methoxyphenylazo)pyridine, 1, and its 3-isomer, 2, have been studied in moderately concentrated sulfuric acid media at 25 °C. In all the acid solutions investigated, 1 reacted faster than 2; rate differences between the two compounds varied from ca. 1000-fold in the dilute region of acidity to ca. 250-fold in the more concentrated acid solutions. The observed first-order rate constants, kψ, for both substrates exhibit a maximum, at ca. 42% H2SO4 and 47% H2SO4 for 1 and 2 respectively. Activation parameters have also been determined. The pKa values for the second protonation equilibria of 1 and 2 have been evaluated and structures of the diprotonated species are discussed. Hydrolysis is shown to occur from the diprotonated substrates and two main mechanisms are operative. The first is an A-2 type mechanism, which involves rate-limiting attack of H2O on the aryl carbon center giving delocalized transition states and intermediates in which the pyridinium and azonium functions are involved in charge delocalization. Subsequent transfer of a proton and detachment of the leaving group are fast processes. In the second A-SE2 type mechanism, nucleophilic attack and transfer of the proton are fast steps preceding the slow general acid catalyzed separation of the leaving group. The difference in reactivity of the two compounds is attributed to differences in extent of charge delocalization in the transition states of the reactions: for 1 both the pyridinium and protonated azonium functions are involved whereas for 2 only the azonium function participates in charge delocalization.

Improved synthesis of anti-sesquinorbornene

1984 ◽  
Vol 62 (9) ◽  
pp. 1840-1844 ◽  
Author(s):  
Karl R. Kopecky ◽  
Alan J. Miller
Keyword(s):  
Acetic Acid ◽  
Sulfuric Acid ◽  
Carboxylic Acid ◽  
Lead Tetraacetate ◽  
Carboxyl Group ◽  
Silver Acetate ◽  
Benzenesulfonyl Chloride ◽  
Methoxide Ion ◽  
Hydrolysis Of ◽  
Monomethyl Ester

Treatment of methyl hydrogen decahydro-1,4:5,8-exo,endo-dimethanonaphthalene-4a,8a-dicarboxylate with lead tetraacetate in benzene – acetic acid replaces the carboxyl group by an acetoxy group. Hydrolysis of this product with 25% sulfuric acid at 130 °C forms 8a-hydroxydecahydro-1,4:5,8-exo,endo-dimethanonaphthalene-4a-carboxylic acid 10. The reaction between 10 and benzenesulfonyl chloride in pyridine containing triethylamine at 95 °C produces anti-sesquinorbornene 1 in 34% yield. In the absence of triethylamine 1 is converted to the hydrochloride. The iodohydroperoxide of 1 is converted by silver acetate at 0 °C to the diketone in a luminescent reaction. The 1,2-dioxetane could not be isolated. Decahydro-1,4:5,8-exo,exo-dimethanonaphthalene-4a,8a-dicarboxylic anhydride is converted slowly by methoxide ion in methanol at 150 °C to the monomethyl ester which then undergoes demethylation. The isomeric exo,endo anhydride undergoes reaction readily with methoxide ion at 80 °C.

scholarly journals Optimized acid hydrolysis of the polysaccharides from the seaweed Solieria filiformis (Kützing) P.W. Gabrielson for bioethanol production

2017 ◽  
Vol 39 (4) ◽  
pp. 423 ◽  
Author(s):  
George Meredite Cunha de Castro ◽  
Norma Maria Barros Benevides ◽  
Maulori Curié Cabral ◽  
Rafael De Souza Miranda ◽  
Enéas Gomes Filho ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Sulfuric Acid ◽  
Acid Hydrolysis ◽  
Kinetic Parameters ◽  
Renewable Resource ◽  
Bioethanol Production ◽  
Seaweed Species ◽  
Mild Conditions ◽  
Hydrolysis Of ◽  
Solieria Filiformis

 The seaweeds are bio-resource rich in sulfated and neutral polysaccharides. The tropical seaweed species used in this study (Solieria filiformis), after dried, shows 65.8% (w/w) carbohydrate, 9.6% (w/w) protein, 1.7% (w/w) lipid, 7.0% (w/w) moisture and 15.9% (w/w) ash. The dried seaweed was easily hydrolyzed under mild conditions (0.5 M sulfuric acid, 20 min.), generating fermentable monosaccharides with a maximum hydrolysis efficiency of 63.21%. Galactose and glucose present in the hydrolyzed were simultaneously fermented by Saccharomyces cerevisiae when the yeast was acclimated to galactose and cultivated in broth containing only galactose. The kinetic parameters of the fermentation of the seaweed hydrolyzed were Y(P⁄S) = 0.48 ± 0.02 g.g−1, PP = 0.27 ± 0.04 g.L−1.h−1, h = 94.1%, representing a 41% increase in bioethanol productivity. Therefore, S. filiformis was a promising renewable resource of polysaccharides easily hydrolyzed, generating a broth rich in fermentable monosaccharides for ethanol production. 

scholarly journals Two-stage, dilute sulfuric acid hydrolysis of wood : an investigation of fundamentals

1985 ◽  
Author(s):  
John F. Harris ◽  
Andrew J. Baker ◽  
Anthony H. Conner ◽  
Thomas W. Jeffries ◽  
James L. Minor ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Acid Hydrolysis ◽  
Two Stage ◽  
Dilute Sulfuric Acid ◽  
Hydrolysis Of

Rate of the Bromous Acid-Bromide Reaction Measured in a Br2-HOBr Buffer System in Sulfuric Acid Solution

1989 ◽  
Vol 44 (6) ◽  
pp. 555-566
Author(s):  
Horst-Dieter Försterling ◽  
Szilvia Murányi ◽  
Helmut Schreiber
Keyword(s):  
Sulfuric Acid ◽  
Acid Solution ◽  
Rate Constant ◽  
Sulfuric Acid Solution ◽  
Solubility Product ◽  
Oxidation States ◽  
Buffer System ◽  
Direct Information ◽  
Hypobromous Acid ◽  
Hydrolysis Of

In the Belousov-Zhabotinsky system bromine species of oxidation states - 1 to 5 are important for the start and for the inhibition of the autocatalytic reaction steps. Especially, the reaction of Br- with HBrO2 competes with the oxidation of Ce3+ by BrO2 formed from HBrO2 and HBrO3. In our investigation the reaction of Br- with HBrO2 (solvent 1 M sulfuric acid) is followed spectroscopically in a mixture of bromine and hypobromous acid, which system works as a buffer for bromide. Including experiments on the hydrolysis of Br2 and on the solubility product of AgBr in 1 M sulfuric acid solution direct information about the rate constant kl of the Br-/HBrO2 reaction is obtained (k1 = 2.5 × 106 M-2 s-1 at 20 °C and 4× 106 M-2 s-1 at 25°C, which values are valid in the range of 0.01 to 1 M sulfuric acid).

Dilute sulfuric acid hydrolysis of Chlorella vulgaris biomass improves the multistage liquid-liquid extraction of lipids

2020 ◽  
Author(s):  
Lorena Borges Martins ◽  
Jimmy Soares ◽  
Wendel Batista da Silveira ◽  
Rita de Cássia Superbi Sousa ◽  
Marcio Arêdes Martins
Keyword(s):  
Sulfuric Acid ◽  
Acid Hydrolysis ◽  
Chlorella Vulgaris ◽  
Liquid Extraction ◽  
Liquid Liquid Extraction ◽  
Dilute Sulfuric Acid ◽  
Hydrolysis Of

scholarly journals Hydrolysis of Formyl Fluoride Catalyzed by Sulfuric Acid and Formic Acid in the Atmosphere

ACS Omega ◽  
2019 ◽  
Vol 4 (21) ◽  
pp. 18996-19004 ◽  
Author(s):  
Lin Zhang ◽  
Bo Long
Keyword(s):  
Sulfuric Acid ◽  
Formic Acid ◽  
Hydrolysis Of
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