Chinazolinderivate durch Cyclodehydrierung von N-(2-substituierten Aryl)-Piperidinen / Quinazoline Derivatives by Cyclodehydrogenation of N-(2-Substituted Aryl)-Piperidines

1999 ◽  
Vol 54 (12) ◽  
pp. 1577-1588 ◽  
Author(s):  
H. Möhrle ◽  
M. Jeandrée
Keyword(s):  
Oxidation Rate ◽  
Reaction Rate ◽  
Product Yield ◽  
Spiro Compounds ◽  
Quantitative Yield ◽  
Cyclic Nitrones ◽  
Quinazoline Derivatives ◽  
Electron Withdrawal

Dehydrogenation of the N-[2-(aminocarbonyl)phenyl]piperidines 1 -5 using Hg(II)-EDTA, generated the quinazolinones 6 -9 . Increasing size of the 4-substituent in the piperidine decreased the oxidation rate and the product yield.N-[2-(Hydroxyiminomethyl)phenyl]piperidines 18-22 showed a different behaviour. While 18 with H g(II)-EDTA in water produced the oxime lactam 24 in quantitative yield, the 4- substituted piperidines 19-21 caused not only a lower reaction rate but also an altered product pattern. The double dehydrogenation to lactams was reduced and the cyclic nitrones, formed by two electron withdrawal, became dominant. From the spiro compounds 21 and 22, solely the quinazoline-N-oxides 29 and 30 resulted. The mechanism of the reactions is discussed.

Nucleophilic cleavage of diaryl disulphides

1973 ◽  
Vol 26 (1) ◽  
pp. 121 ◽  
Author(s):  
DAR Happer ◽  
JW Mitchell ◽  
GJ Wright
Keyword(s):  
Transition State ◽  
Reaction Rate ◽  
Substituent Effects ◽  
Butyl Alcohol ◽  
Sulphur Atom ◽  
Cyanide Ion ◽  
Benzene Rings ◽  
Nucleophilic Cleavage ◽  
Rapid Equilibrium ◽  
Electron Withdrawal

The rates of cleavage of 14 symmetrically substituted diaryl disulphides by cyanide ion have been measured in 60% aqueous t-butyl alcohol at pH 9.2. A plot of log k against σ� shows that while the reaction rate is accelerated by inductive electron withdrawal from the benzene rings, substituents capable of conjugative interaction are not correlated by their σ� parameters. +R substituents cause reaction to occur much faster than predicted on the basis of their σ� values, while -R substituents react more slowly than predicted. Measurement of rates of cleavage of three series of unsymmetrically substituted disulphides by cyanide or hydroxide shows that these unusual substituent effects arise from substituents in the thiocyanate-forming aryl ring. This behaviour is explained in terms of a change in the electronic behaviour of the thio- cyanate-forming sulphur atom from -I, + R in the disulphide to -I,-R in the rate-determining transition state for the reaction. The study does not show whether the cleavage involves an SN2 process or rapid equilibrium formation of a pentacovalent intermediate.

Reaction rate, fission product yield, and Rossi-α measurements using a HEU metal, copper reflected critical assembly

2015 ◽  
Vol 52 (7-8) ◽  
pp. 1018-1025 ◽  
Author(s):  
Rene Sanchez ◽  
John Bounds ◽  
Todd Bredeweg ◽  
Joetta Goda ◽  
Travis Grove ◽  
...  
Keyword(s):  
Fission Product ◽  
Reaction Rate ◽  
Product Yield ◽  
Critical Assembly ◽  
Fission Product Yield

A Much-Needed Mechanism and Reaction Rate for the Oxidation of Phenols with ClO2: A Joint Experimental and Computational Study

2013 ◽  
Vol 66 (7) ◽  
pp. 814 ◽  
Author(s):  
Carlos Alberto Huerta Aguilar ◽  
Jayanthi Narayanan ◽  
Mariappan Manoharan ◽  
Narinder Singh ◽  
Pandiyan Thangarasu
Keyword(s):  
Oxidation Rate ◽  
Density Functional ◽  
Reaction Rate ◽  
Computational Study ◽  
Reaction Rate Constant ◽  
Oxidation Products ◽  
Gas Chromatography Mass Spectrometry ◽  
Activation Barriers ◽  
Oxidation Of Phenols ◽  
The Right

The oxidation of phenols with chlorine dioxide, a powerful means to eliminate phenol pollutants from drinking water, is explored. Kinetic experiments reveal that 2,4,6-trichlorophenol exhibits a lower oxidation rate than other phenols because the chlorine atoms (σ = 0.22) at ortho and para-positions decrease the benzene’s electron density, in agreement with the Hammett plot. The oxidation of phenol was found to be second order with respect to phenol and first order with respect to ClO2 and a possible mechanism is proposed. The phenol/ClO2 oxidation was found to be pH-dependent since the reaction rate constant increases with increasing pH. The oxidation rate was also significantly enhanced with an increasing methanol ratio in water. The oxidation products, such as benzoquinones, were analysed and confirmed by liquid chromatography and gas chromatography–mass spectrometry. Density functional theory computations at both the B3LYP/6-311+G(d,p) and M06-2X.6-311+G(d,p) levels with the SCRF-PCM solvation model (i.e. with water) further supported the proposed mechanisms in which activation barriers predicted the right reactivity trend as shown by the kinetic experiments.

scholarly journals MATHEMATICAL MODELING OF THE 3(Н)-QUINAZOLIN-4-ONЕ SYNTHESIS PROCESS

2021 ◽  
pp. 51-57
Keyword(s):  
Mathematical Modeling ◽  
Reaction Rate ◽  
Linear Equations ◽  
Product Yield ◽  
Farm Animals ◽  
Synthesis Process ◽  
Optimal Conditions ◽  
System Of Linear Equations ◽  
Molar Ratios ◽  
The Matrix

The aim is to optimize the conditions for the synthesis of 3(H)-quinazolin-4-one by the method of mathematical modeling to develop a technology for producing the substance of a new domestic drug used in the treatment of farm animals from helminths. In mathematical modeling, the method of a small number of squares was used. Analytical dependences of the product yield on temperature, reaction time, and molar ratios of the starting materials were determined. A system of linear equations has been compiled. The system of linear equations was performed by the matrix method (A, B, C).The average reaction rate was determined. Based on the results obtained, a 3(H)-quinazolin-4-one diagram using the Maple 18 program and an icon diagram of the reaction duration, temperature, and reaction rate are shown. Based on the results of mathematical modeling, a highly efficient technological scheme for obtaining 3(H)-quinazolin-4-one has been developed. Based on this technology, compound 3(H)-quinazolin-4-one was synthesized in quantitative products at the Institute of Plant Chemistry, at a pilot production plant.The results obtained confirmed the found optimal conditions

scholarly journals An “ideal lignin” facilitates full biomass utilization

2018 ◽  
Vol 4 (9) ◽  
pp. eaau2968 ◽  
Author(s):  
Yanding Li ◽  
Li Shuai ◽  
Hoon Kim ◽  
Ali Hussain Motagamwala ◽  
Justin K. Mobley ◽  
...  
Keyword(s):  
Plant Growth ◽  
Lignocellulosic Biomass ◽  
Growth And Development ◽  
Product Yield ◽  
Structural Heterogeneity ◽  
Quantitative Yield ◽  
Plant Growth And Development ◽  
Biomass Utilization ◽  
Major Impediment

Lignin, a major component of lignocellulosic biomass, is crucial to plant growth and development but is a major impediment to efficient biomass utilization in various processes. Valorizing lignin is increasingly realized as being essential. However, rapid condensation of lignin during acidic extraction leads to the formation of recalcitrant condensed units that, along with similar units and structural heterogeneity in native lignin, drastically limits product yield and selectivity. Catechyl lignin (C-lignin), which is essentially a benzodioxane homopolymer without condensed units, might represent an ideal lignin for valorization, as it circumvents these issues. We discovered that C-lignin is highly acid-resistant. Hydrogenolysis of C-lignin resulted in the cleavage of all benzodioxane structures to produce catechyl-type monomers in near-quantitative yield with a selectivity of 90% to a single monomer.

scholarly journals EFFECT OF PROPELLER MIXER TURNS NUMBER ON THE SULFIDES OXIDATION RATE IN THE OIL PHASE IN A MIXING REACTOR

2019 ◽  
Vol 20 (9-10) ◽  
pp. 79-83
Author(s):  
R. E. Lipantyev ◽  
V. P. Tutubalina
Keyword(s):  
Hydrogen Peroxide ◽  
Rotation Number ◽  
Oxidation Rate ◽  
Reaction Rate ◽  
Acid Catalyst ◽  
Oil Fraction ◽  
Sulfides Oxidation ◽  
Propeller Mixer

The effect of the rotation number of the propeller mixer on the concentration of sulfoxide sulfur in the oil fraction of Arlan oil during the oxidation of this fraction sulfides with hydrogen peroxide along with an acid catalyst, a mixture of formic and sulfuric acids in a mixing reactor, was studied. The dependences of the concentration of sulfoxide sulfur in the oil fraction and the reaction rate of the oxidation of the fraction sulfides to sulfoxides are obtained experimentally depending on the intensity of heterogeneous blend mixing in the blending reactor. 

Investigation Of Kinetic Regularities For Obtaining Methyl-1,3,4- Trimethylcyclohex-3-Encarboxylate By Reaction Of Diels-Alder

2019 ◽  
Vol 14 (4) ◽  
pp. 208-215
Author(s):  
I.S. Kostiv ◽  
R.I. Havryliv
Keyword(s):  
Rate Constants ◽  
Reaction Rate ◽  
Activation Parameters ◽  
Product Yield ◽  
Alder Reaction ◽  
Diels Alder ◽  
Molar Ratio ◽  
Target Product ◽  
Reaction Rate Constants ◽  
Diels Alder Reaction

Kinetics of the reaction of the cycloaddition of 2,3-dimethylbuta-1,3-diene (DMB) and methylmethacrylate (MMA) by the Diels-Alder reaction was studied. Reaction rate constants k = 4.4∙10-6 l/(mol∙s) at T = 403 K; k = 10.0∙10-6 l/(mol∙s) at T = 413 K; k = 15.8∙10-6 l/(mol∙s) at T = 423 K; k = 19.4∙10-6 l/(mol∙s) at T = 433 K and the activation parameters of the reaction Eakt = 75.2 kJ/mol, ΔS = -146.8 J/(mol∙K), ΔH = 73.9 kJ/mol were determined. Influence of temperature, molar ratio of reagents on the yield of the target product was investigated. At temperature increase from 403 to 433 K, methyl-1,3,4-trimethylcyclohex-3-encarboxylate (MTMCHC) yield increases from 78 % to 92 %. With further increase in temperature, DMB boils and MMA remains in a liquid state, accordingly it is not expected that the target product yield will materially increase. An increase in the excess of DMB: МMA from 1:1 to 2.5:1 makes it possible to increase yield of MTMCHC from 65 % to 92 %. The production of methyl-1,3,4-trimethylcyclohex-3-encarboxylate at the optimal conditions was established: temperature of 423−433 K and molar ratio of reagents DMB:MMA = 1.5:1, the yield of MTMCHC reaches 89−92 % at productivity of 101−105 g/(l·h). Based on the obtained reaction rate constants and the activation parameters of the [4+2]-cyclic addition of 2,3-dimethylbuta-1,3-diene and methylmethacrylate, it was found that the reaction under study is subject to the kinetic law of the second order.

New Procedure for Linear Sweep Voltammetric Determination of Catalytic Reaction Rate Constant. Oxidation of Some Aliphatic Alcohols with Electrolytically Generated Os(VIII)

1995 ◽  
Vol 60 (5) ◽  
pp. 795-801
Author(s):  
Dušan Bustin ◽  
Štefan Mesároš ◽  
Peter Tomčík ◽  
Miroslav Rievaj
Keyword(s):  
Catalytic Reaction ◽  
Oxidation Rate ◽  
Reaction Rate ◽  
Reaction Rates ◽  
Reaction Rate Constant ◽  
Sufficient Accuracy ◽  
Aliphatic Alcohols ◽  
Catalytic Reactions ◽  
Linear Sweep

Oxidation rate of methanol, ethanol and 2-propanol by Os(VIII) in 1 M KOH was determined by evaluating anodic voltammograms of Os(VI) in the presence of the aliphatic alcohols. The proposed method is based on the evaluation of the change of voltammogram shape by catalytic process and on the assumption of its approximation by fractionally integrated voltammograms. This assumption has been confirmed empirically for k'f /a in the interval of <0.04,1>. The rate constants from this interval could be determined with sufficient accuracy. The method is suitable for evaluation of reaction rates slow and moderately fast catalytic reactions. It was compared with other evaluation methods from the literature.

scholarly journals Study on detoxification property of alkaline-modified MoO42--H2O2 decontaminants against PhSMe under subzero environment

2021 ◽  
Vol 267 ◽  
pp. 02061
Author(s):  
Shaohua Wei ◽  
Hongpeng Zhang ◽  
Haiyan Zhu ◽  
Lianyuan Wang ◽  
Jing Liang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Rate Constants ◽  
Oxidation Rate ◽  
Oxidation Reaction ◽  
Reaction Rate ◽  
Reaction Rate Constants ◽  
Relative Ratio ◽  
Reaction Activation Energy ◽  
Oxidation Reaction Rate

The decontaminant activated by MoO42- (MoO42--H2O2) suitable for subzero environment shows strong oxidizing ability and weak nucleophilicity due to its acid. In this paper, in order to improve nucleophilicity and retain oxidation of MoO42--H2O2 as far as possible, NH3 and NaOH were used as alkaline modifiers, and PhSMe was used as a simulant of HD to study the oxidation rate and products of sulfides by alkaline-modified MoO42--H2O2 below zero. Results showed that the reaction rate constants decreased with the increase of pH in both NH3 and NaOH modified MoO42--H2O2 at -20°C, and the relative ratio of sulfone to sulfoxide increased especially at pH>9. The reaction activation energy Ea of PhSMe oxidation in the alkaline-modified MoO42--H2O2 decontaminants was lower than that in the MoO42--H2O2 decontaminant, which indicated that the sensitivity of the oxidation reaction rate to temperature in MoO42--H2O2 was reduced after modification.

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