Kinetics and mechanism of alkaline hydrolysis of (Z)-O-(N-4-nitrophenylcarbamoyl)benzaldoximes in 30% aqueous ethanol

1979 ◽  
Vol 44 (8) ◽  
pp. 2401-2408
Author(s):  
Jaromír Mindl ◽  
František Radonský ◽  
Jiří Klicnar ◽  
Miroslav Večeřa
Keyword(s):  
Ir Spectra ◽  
Alkaline Medium ◽  
Alkaline Hydrolysis ◽  
Reaction Rate ◽  
Aqueous Ethanol ◽  
Hydrogen Ion ◽  
Neutral Medium ◽  
Spontaneous Hydrolysis ◽  
Hydrolysis Rates ◽  
Hydrolysis Of

Alkaline hydrolysis of (Z)-O-(N-4-nitrophenylcarbamoyl)benzaldoximes (I), the configuration of which was verified by IR spectra, produces a mixture of Z and E-benzaldoximates II and III, benzonitrile IV, and 4-nitrophenylcarbamate ion (V). In subsequent reactions II and III are hydrolyzed to benzaldehyde VI, and III and IV give finally benzoate VII. The carbamate V is decarboxylated to 4-nitroaniline (VIII). The compound I is hydrolyzed to oxime and 4-nitroaniline (VIII) in neutral medium. The hydrolysis rates of three compounds type I have been measured in 30% aqueous ethanol at pH 4 to 14. Character of the hydrolysis course in alkaline medium corresponds to a reaction of E1cB type. In neutral medium spontaneous hydrolysis with water takes place and the reaction rate is independent of concentration of hydrogen ion.

Effect of Vapor Pressure of H2O on the Formation of Nano-Crystalline TiO2 Ultrafine Powders

1999 ◽  
Vol 581 ◽  
Author(s):  
K. R. Lee ◽  
S. J. Kim ◽  
J. S. Song ◽  
S. Park
Keyword(s):  
Vapor Pressure ◽  
Reaction Rate ◽  
Ph Value ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Precipitation Process ◽  
Nano Crystalline ◽  
Natural Decrease ◽  
Spontaneous Hydrolysis ◽  
Hydrolysis Of

ABSTRACTMono-dispersed TiO2 ultrafme particles with diameters 40-400nm were obtained from aqueous TiOCl2 solution with 0.67M Ti4+ concentration prepared diluting TiCl4 by homogeneous precipitation process in the ranges of 17-230°C. With the spontaneous hydrolysis of TiOCl2, which means the natural decrease of pH value in the aqueous solution, all mono-dispersed precipitates were crystallized with the anatase or rutile TiO2 phase. TiO2 precipitate with the pure rutile phase was fully formed at the temperatures below 65 °C, not involving the evaporation of H2O, and above 155 °C, which were available by suppressing it. TiO2 precipitate with rutile phase including a small amount of the anatase phase started to be formed in the intermediate temperatures above 70 °C showing the full formation of the anatase above 95 °C under the free evaporation of H2O. However, in the case of completely suppressing H2O evaporation at the temperatures above 70°C, TiO2 precipitate with anatase phase was fully transformed into the precipitate with the rutile phase by the vapor pressure of H2O. Therefore, the formation of TiO2 precipitates with the rutile phase around room temperature would be caused due to the existence of the capillary pressure between the agglomerated needle-shaped particles or the ultrafme clusters, together with the slow reaction rate.

Effect of the α- and γ-Hydroxyls on the Alkaline Hydrolysis Rate of Nonphenolic β-0-4 Lignin Diastereomers

Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Dexter L. Criss ◽  
Thomas Elder ◽  
Thomas H. Fisher ◽  
Tor P. Schultz
Keyword(s):  
Computational Modeling ◽  
Alkaline Hydrolysis ◽  
Rate Ratio ◽  
Electronic Effect ◽  
Activation Parameters ◽  
Hydrolysis Rate ◽  
Significant Extent ◽  
Hydrolysis Rates ◽  
Lignin Model ◽  
Hydrolysis Of

Summary Nonphenolic β-0-4 erythro and threo lignin model diastereomers with various γ-groups (CH3, CH2-O-CH3, and CH2OH) and Cα-substituents (OH, OCH3) were synthesized, and the alkaline hydrolysis rates and activation parameters determined. In addition, two of the diastereomer pairs were computationally modeled and the thermodynamic values for the ionization of the α- or γ-hydroxyl, and subsequent displacement of the phenolate group to form an epoxide intermediate, were determined. The results suggest that the erythro γ-hydroxyl may participate in the hydrolysis to a significant extent, which results in a relatively high erythro/threo rate ratio for the α,γ-di-OH isomers. The influence of the erythro γ-hydroxyl on the hydrolysis rate may be due to the relatively favorable stability of the erythro γ-oxyanion. The electronic effect of the g-substituent appears to influence how fast the α-hydroxyl displaces the phenoxyl. We had previously suggested that the γ-substituent sterically inhibits hydrolysis of the threo isomer, and computational modeling confirmed this.

Synthesis and properties of 5-styryl-2-furancarboxylic acids

1981 ◽  
Vol 46 (11) ◽  
pp. 2724-2728 ◽  
Author(s):  
Viera Knoppová ◽  
Anton Beňo ◽  
Jaroslav Kováč
Keyword(s):  
Ir Spectra ◽  
Transmission Coefficient ◽  
Alkaline Hydrolysis ◽  
Methyl Esters ◽  
Uv And Ir Spectra ◽  
Substituted Benzaldehydes ◽  
Hydrolysis Of

5-(4-X-Styryl)-2-furancarboxylic acids (X = H, Br, NO2, COOCH3, (CH3)2N) were prepared by oxidation of the appropriate 5-(4-X-styryl)-2-furaldehydes, or alternatively by alkaline hydrolysis of the corresponding methyl esters. The latter were obtained by reacting the 4-substituted benzaldehydes with 5-methoxycarbonylfuryltriphenylphosphonium chloride. The UV and IR spectra of products are commented. The apparent pK values of the synthesized acids were employed for calculation of the transmission coefficient π' through the benzene-furan system bridged by a -CH=CH- group.

Alkaline Hydrolysis of Nonphenolic β-0-4 Lignin Models: Substituent Effect of the A-Ring on the Rate

Holzforschung ◽  
2002 ◽  
Vol 56 (6) ◽  
pp. 592-594 ◽  
Author(s):  
T. P. Schultz ◽  
T. H. Fisher
Keyword(s):  
Alkaline Hydrolysis ◽  
Substituent Effect ◽  
Hydrolysis Rate ◽  
Side Reactions ◽  
Hydrolysis Rates ◽  
Hydrolysis Of ◽  
Electron Withdrawing Substituents

Summary Six nonphenolic β-0-4 lignin models substituted on the phenyl A-ring [unsubstituted; 3,5-dimethoxyl; 3,4-dimethoxyl; 3-methoxyl; 4-methoxyl; and 4-methyl] were synthesized and the alkaline hydrolysis rates at 170°C determined. Electron-withdrawing substituents enhanced the hydrolysis rate, but this effect was relatively minor. Over 90% of the disappearance of the dimer could be accounted for by appearance of the B-ring phenolic product for all compounds, which suggests that minimal side reactions occurred.

Preparation of a new metallomicelle catalyst for the hydrolysis of bis(4-nitrophenyl) phosphate

2013 ◽  
Vol 67 (4) ◽  
Author(s):  
Jia-Qing Xie ◽  
Ci Li ◽  
Min Wang ◽  
Bing-Ying Jiang
Keyword(s):  
Reaction Rate ◽  
Active Species ◽  
Local Concentration ◽  
Catalytic Hydrolysis ◽  
Catalytic Function ◽  
Nitrophenyl Phosphate ◽  
Spontaneous Hydrolysis ◽  
Lauryl Ether ◽  
Hydrolysis Of ◽  
Bnpp Hydrolysis

AbstractA new metallomicellar system containing cerium(III), a macrocylic polyamine ligand, and the nonionic surfactant Brij35(polyoxyethylene(23) lauryl ether) was prepared and used as a catalyst in the hydrolysis of bis(4-nitrophenyl) phosphate (BNPP). Catalytic rate of the BNPP hydrolysis was measured kinetically using the UV-VIS spectrophotometric method. The results indicate that the metallomicellar system has relatively high stability and excellent catalytic function in the BNPP hydrolysis; also, the reaction rate of the BNPP catalytic hydrolysis increased by a factor of ca. 1 × 1010 compared to the BNPP spontaneous hydrolysis due to the catalytic effect of the active species and the local concentration effect of the micelles in the metallomicellar system. Experimental results also showed that the mono-hydroxy complex containing the macrocyclic polyamine ligand and cerium(III) is the real active species in the BNPP catalytic hydrolysis, and that the micelles provide a useful catalytic environment for the reaction. On basis of the research results, the reaction mechanism of BNPP catalytic hydrolysis has been proposed.

Effect of OH- Concentration on Alkaline Hydrolysis of Diphenyl (4-Nitrophenyl) Phosphate Catalyzed by 2-Iodosobenzoic and 3-Iodoso-2-naphthoic Acids

1994 ◽  
Vol 59 (5) ◽  
pp. 1137-1144 ◽  
Author(s):  
Aleš Ptáček ◽  
Jiří Kulič
Keyword(s):  
Alkaline Hydrolysis ◽  
Reaction Rate ◽  
Ion Concentration ◽  
Molar Ratio ◽  
Hexadecyltrimethylammonium Bromide ◽  
Ph Values ◽  
Nitrophenyl Phosphate ◽  
Naphthoic Acid ◽  
Iodosobenzoic Acid ◽  
Hydrolysis Of

The hydrolysis of diphenyl (4-nitrophenyl) phosphate catalyzed by 2-iodosobenzoic and 3-iodoso-2-naphthoic acids has been studied at different pH values in the presence of hexadecyltrimethylammonium bromide as a micellar agent. It was found that 3-iodoso-2-naphthoic acid is better catalyst than 2-iodosobenzoic acid. At amounts of the acids higher than stoichiometric, the reaction is independent of pH in the 8.00 to 10.00 region while on using substoichiometric amounts, the reaction rate depends on OH- ion concentration only when the acid to diphenyl (4-nitrophenyl) phosphate molar ratio amounts to 12.5 : 1 for 2-iodosobenzoic acid and 6.25 : 1 for 3-iodoso-2-naphthoic acid.

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