Hydrolysis kinetics and mechanism of acyl-1,3-diphenyltriazenes

1980 ◽  
Vol 45 (4) ◽  
pp. 1269-1278 ◽  
Author(s):  
Oldřich Pytela ◽  
Miroslav Večeřa ◽  
Pavel Vetešník
Keyword(s):  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Aqueous Media ◽  
Activation Parameters ◽  
Base Catalysis ◽  
Hydrolysis Rate ◽  
Chemical Calculation ◽  
Hydrolysis Kinetics ◽  
Acid And Base ◽  
Acid Catalyzed

The hydrolysis rate constants of 3-(N-methylcarbamoyl)-1,3-diphenyltriazene (I), 3-(N-phenylcarbamoyl)-1,3-diphenyltriazene (II) and 3-acetyl-1,3-diphenyltriazene (III) have been determined in aqueous media within pH 0 to 14, Ho to 3 and H- to 15. The hydrolysis at pH < 2 and pH > 11 show specific acid and base catalysis, respectively, whereas within pH 2 to 11 non-catalyzed hydrolysis takes place. Activation parameters of the non-catalyzed and catalyzed hydrolysis have been determined. Quantum-chemical calculation of 3-carbamoyltriazene (IV) has been carried out by the MINDO/2 method. Hydrolysis mechanism of the studied compounds is suggested for the non-catalyzed, specific acid catalyzed and specific base catalyzed hydrolysis.

Kinetics and mechanism of hydrolysis of substituted phenyl N-(4-methylphenyl)sulphonylcarbamates. Solvolysis of 3-nitrophenyl N-(4-methylphenyl)-sulphonylcarbamate in mixtures water-1,4-dioxane and water-tert-butyl alcohol and its decomposition to neutral molecules in non-aqueous media

1979 ◽  
Vol 44 (9) ◽  
pp. 2639-2652 ◽  
Author(s):  
Jitka Moravcová ◽  
Miroslav Večeřa
Keyword(s):  
Organic Solvents ◽  
Ph Dependence ◽  
Aqueous Media ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Base Catalysis ◽  
Hydrolysis Rate ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Hydrolysis Of

pH Dependence of hydrolysis rate of the substituted phenyl N-(4-methylphenyl)sulphonylcarbamates has been followed in aqueous medium. The activation parameters and the Hammet reaction constant (ρ = 2.4) have been determined at pH 11.3. For hydrolysis of 3-nitrophenyl N-(4-methylphenyl)sulphonylcarbamate (pK about 3.5) no general base catalysis has been found. The hydrolysis mechanism is discussed. Perturbation of the water structure by organic solvents (1,4-dioxane and tert-butyl alcohol) has been used for differentiation of ElcB and Bac2 mechanisms, 2,4-dinitrophenyl acetate being used for comparison. The decomposition rates of 3-nitrophenyl N(4-methylphenyl)sulphonylcarbamate have been determined in six organic solvents. Mechanism of spontaneous splitting of the carbamate molecule in non-aqueous media is discussed.

Hydration reactivity of ketenes generated by flash photolysis

1987 ◽  
Vol 65 (8) ◽  
pp. 1719-1723 ◽  
Author(s):  
Annette D. Allen ◽  
A. Jerry Kresge ◽  
Norman P. Schepp ◽  
Thomas T. Tidwell
Keyword(s):  
Flash Photolysis ◽  
Aqueous Media ◽  
Phenyl Group ◽  
Base Catalysis ◽  
Nucleophilic Attack ◽  
Ultraviolet Spectrophotometry ◽  
Acid And Base ◽  
Acid Catalyzed ◽  
Acid And Base Catalysis

The ketenes n-BuCH=C=O, PhCH=C=O, and Ph2C=C=O have been generated by flash photolysis and their reactivities toward water, including acid and base catalysis, have been measured in wholly aqueous media by ultraviolet spectrophotometry. The phenyl group electronically enhances the reactivity of ketenes relative to n-butyl toward water and hydroxide, but retards reaction with protic acids. The presence of bulky groups, including phenyls, on each side in the ketene plane sterically retards nucleophilic attack. The reactions are interpreted as involving in-plane attack by nucleophilic water or hydroxide in the neutral and base-induced reactions, and electrophilic protonation perpendicular to the ketene plane for the acid-catalyzed reaction.

Examination on Permittivity Estimation of Hydrocarbon-based Thermosetting Resin based on Quantum Chemical Calculation

2017 ◽  
Vol 137 (11) ◽  
pp. 626-631 ◽  
Author(s):  
Yuki Fuchi ◽  
Ryota Nakasako ◽  
Masahiro Kozako ◽  
Masayuki Hikita ◽  
Nobuhito Kamei
Keyword(s):  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Chemical Calculation ◽  
Thermosetting Resin

Effect of temperature on chiroptical and conformational properties of acyclic ketoses

1980 ◽  
Vol 45 (2) ◽  
pp. 475-481
Author(s):  
Slavomír Bystrický ◽  
Tibor Sticzay ◽  
Igor Tvaroška
Keyword(s):  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Conformational Mobility ◽  
Effect Of Temperature ◽  
Chemical Calculation ◽  
Cd Spectra ◽  
Conformational Properties ◽  
Temperature Dependences

Conformational mobility of tetruloses, 2-pentuloses, D-3-pentulose and 4-deoxy-L-pentulose was studied by measuring temperature dependences of CD spectra in the region +40°C to -140°C in a methanol-ethanol (1:4) mixture. The changes in spectra reflect the population of rotamers around bonds to the carbonyl chromophore. The most stable conformers were determined by PCILO quantum chemical calculation.

scholarly journals Preamble from the Guest Editor of Special Issue “DFT Quantum-Chemical Calculation of Metal Clusters”

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 442
Author(s):  
Oleg V. Mikhailov
Keyword(s):  
Guest Editor ◽  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Chemical Structure ◽  
Metal Clusters ◽  
Chemical Calculation ◽  
Special Issue

As known, the concept of “cluster” is collective and includes substances that are quite diverse in composition and chemical structure [...]

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