HYDROLYSIS AND POLYMERIZATION OF CYCLIC DIMETHYLETHYLENE OXALATES

1951 ◽  
Vol 29 (11) ◽  
pp. 970-973 ◽  
Author(s):  
L. G. Ripley ◽  
R. W. Watson
Keyword(s):  
Elevated Temperature ◽  
Optical Activity ◽  
Vacuum Distillation ◽  
Room Temperature ◽  
Order Reaction ◽  
Membered Ring ◽  
Melting Points ◽  
Monobasic Acid ◽  
First Order ◽  
Marked Stability

Macrocrystalline cyclic oxalates (2,3-dimethyl-5-6-p-dioxanediones) were prepared by vacuum distillation of the polymeric mixture formed on heating ethyl oxalate, and 1, 2-dimethylethylene glycol with an ester-interchange catalyst. Monomeric dimethylethylene oxalate polymerizes less readily than propylene oxalate, and only at an elevated temperature in the presence of a catalyst. Dimethyl substitution therefore confers marked stability on the six-membered ring. Hydrolysis reaches 50% completion almost instantaneously, followed by a slow first order reaction resulting in complete cleavage of the monobasic acid in about one month at room temperature. Hydrolysis constants for the levo- and meso- oxalates are 0.069 and 0.076 days−1 respectively. The crystalline monomers do not possess sharp melting points and represent stereoisomeric mixtures which display optical activity in solution.

Polymerization Reactions under high Pressure. I. Some Experiments with Isoprene and Butyraldehyde

1930 ◽  
Vol 3 (3) ◽  
pp. 472-482
Author(s):  
J. B. Conant ◽  
C. O. Tongberg
Keyword(s):  
High Pressure ◽  
Room Temperature ◽  
High Pressures ◽  
Order Reaction ◽  
Pressure Coefficients ◽  
First Order ◽  
Rate Of Polymerization ◽  
Energy Relationships ◽  
Temperature And Pressure ◽  
Autocatalytic Effect

Abstract 1. The rate of polymerization of isoprene under high pressures has been studied. The reaction is subject to positive catalysis by peroxides and negative catalysis by hydroquinone. Although the reaction is of a high order, the rate is approximately in accord with a first order reaction presumably because of an autocatalytic effect. The temperature and pressure coefficients of the rate have been estimated. The solubility and elasticity of the product depend on the extent to which the isoprene has been polymerized; when the polymerization is practically complete at room temperature at 12,000 atm. the product is very insoluble 2. The action of high pressures on n-butyraldehyde produces a solid only slightly soluble in organic solvents. It reverts to n-butyraldehyde rapidly. It is suggested that this polymer is similar to the well-known polymers of formaldehyde but that the energy relationships are such that the polymer is stable only at high pressures.

The formation of O2(a1Δg) in homogeneous and heterogeneous atom recombination

1986 ◽  
Vol 64 (12) ◽  
pp. 1614-1620 ◽  
Author(s):  
A. A. Ali ◽  
E. A. Ogryzlo ◽  
Y. Q. Shen ◽  
P. T. Wassell
Keyword(s):  
Kinetic Study ◽  
Gas Phase ◽  
Molecular Oxygen ◽  
Rate Constant ◽  
Room Temperature ◽  
High Efficiency ◽  
Flow System ◽  
Order Reaction ◽  
Third Order ◽  
First Order

The recombination of oxygen atoms has been studied in a discharge flow system at room temperature. The yield of O2(a1Δg) in the recombination on Pyrex has been found to be 0.08 (±0.02). In the gas phase, O2(a) was found to be formed in a process that is second order in [O] and first order in [N2]. The rate constant for this third-order reaction was found to be 3.4 (±0.4) × 10−34 cm6∙molecule−2∙s−1, representing a yield of 0.07 (±0.02). In the presence of molecular oxygen, the rate of production of O2(a) was found to increase. A kinetic study of this effect led to the conclusion that collisions of molecular oxygen with an unidentified precursor can produce O2(a) with high efficiency.

scholarly journals Synthesis of new series of Pyrazoline, and study their Kinetics and Reaction Mechanism

2019 ◽  
Vol 7 (2) ◽  
pp. 5-13
Author(s):  
Kosrat N. Kaka ◽  
Salam G. Taher ◽  
Wali M. Hamad ◽  
Aram H. Ibrahim
Keyword(s):  
Free Energy ◽  
Reaction Mechanism ◽  
Thermodynamic Parameters ◽  
Compensation Effect ◽  
New Products ◽  
Order Reaction ◽  
Membered Ring ◽  
Free Energies ◽  
First Order ◽  
Kinetics Of

A new series of novel pyrazoline compounds were synthesized by addition of thiosemicarbazide to the 2,6-dibenzylidenecyclohexanone (Chalcone) and its para substituted derivatives. This study was conducted for four purposes. Firstly, a series of five membered ring pyrazoline compounds were synthesized and the structure of all new products obtained are supported by spectral data (1H-NMR, 13CNMR, IR and UV-Vis.), and the effect of substituents were studied. Secondly, the reaction kinetics of the new synthesized compounds were studied to investigate the reaction mechanism pathway and order of the reaction; it was found that, the reaction undergoes via Claisen route of mechanism with first-order reaction. Thirdly, the thermodynamics of the reaction were studied, the rate of the reaction, Arrhenius parameters (A), and thermodynamic parameters for activation includes (free energies (Ea), entropies (ΔS#), and Gibbs free energy (ΔG#) were estimated. Finally, the compensation effect was also studied, and found the same pathway for all of the synthesized pyrazoline compounds.

Leaching Kinetics of Atrazine and Inorganic Chemicals in Tilled and Orchard Soils

2014 ◽  
Vol 28 (2) ◽  
pp. 231-237 ◽  
Author(s):  
Lech W. Szajdak ◽  
Jerzy Lipiec ◽  
Anna Siczek ◽  
Artur Nosalewicz ◽  
Urszula Majewska
Keyword(s):  
Reaction Rate ◽  
Inorganic Compounds ◽  
Model Performance ◽  
Order Reaction ◽  
First Order Reaction ◽  
Order Kinetic ◽  
Time Data ◽  
First Order ◽  
Concentration Changes ◽  
Reaction Constants

Abstract The aim of this study was to verify first-order kinetic reaction rate model performance in predicting of leaching of atrazine and inorganic compounds (K+1, Fe+3, Mg+2, Mn+2, NH4 +, NO3 - and PO4 -3) from tilled and orchard silty loam soils. This model provided an excellent fit to the experimental concentration changes of the compounds vs. time data during leaching. Calculated values of the first-order reaction rate constants for the changes of all chemicals were from 3.8 to 19.0 times higher in orchard than in tilled soil. Higher first-order reaction constants for orchard than tilled soil correspond with both higher total porosity and contribution of biological pores in the former. The first order reaction constants for the leaching of chemical compounds enables prediction of the actual compound concentration and the interactions between compound and soil as affected by management system. The study demonstrates the effectiveness of simultaneous chemical and physical analyses as a tool for the understanding of leaching in variously managed soils.

The Kinetics of Glucose Decomposition with Sulfate Reduction in the Anaerobic Fluidized Bed Reactor

1993 ◽  
Vol 28 (2) ◽  
pp. 135-144 ◽  
Author(s):  
S. Matsui ◽  
R. Ikemoto Yamamoto ◽  
Y. Tsuchiya ◽  
B. Inanc
Keyword(s):  
Sulfate Reduction ◽  
Fluidized Bed ◽  
Kinetic Equations ◽  
Fluidized Bed Reactor ◽  
Order Reaction ◽  
First Order Reaction ◽  
First Order ◽  
Glucose Decomposition ◽  
Reaction Equations ◽  
Kinetics Of

Using a fluidized bed reactor, experiments on glucose decomposition with and without sulfate reduction were conducted. Glucose in the reactor was mainly decomposed into lactate and ethanol. Lactate was mainly decomposed into propionate and acetate, while ethanol was decomposed into propionate, acetate, and hydrogen. Sulfate reduction was not involved in the decomposition of glucose, lactate, and ethanol, but was related to propionate and acetate decomposition. The stepwise reactions were modeled using either a Monod expression or first order reaction kinetics in respect to the reactions. The coefficients of the kinetic equations were determined experimentally. The modified Monod and first order reaction equations were effective at predicting concentrations of glucose, lactate, ethanol, propionate, acetate, and sulfate along the beight of the reactor. With sulfate reduction, propionate was decomposed into acetate, while without sulfate reduction, accumulation of propionate was observed in the reactor. Sulfate reduction accelerated propionate conversion into acetate by decreasing the hydrogen concentration.

Complete monotonicity of entropy production in chemical reaction

1981 ◽  
Vol 46 (2) ◽  
pp. 452-456
Author(s):  
Milan Šolc
Keyword(s):  
Entropy Production ◽  
Equilibrium Constant ◽  
Chemical Reaction ◽  
Relative Entropy ◽  
Order Reaction ◽  
Complete Monotonicity ◽  
First Order Reaction ◽  
First Order ◽  
Completely Monotonic ◽  
Derivatives Of

The successive time derivatives of relative entropy and entropy production for a system with a reversible first-order reaction alternate in sign. It is proved that the relative entropy for reactions with an equilibrium constant smaller than or equal to one is completely monotonic in the whole definition interval, and for reactions with an equilibrium constant larger than one this function is completely monotonic at the beginning of the reaction and near to equilibrium.

Photocolouration of 2,4,4,6-Tetraaryl-4H-pyrans and Their Heteroanalogues: Importance of Hypervalent Photoisomers

1995 ◽  
Vol 60 (10) ◽  
pp. 1621-1633 ◽  
Author(s):  
Stanislav Böhm ◽  
Mojmír Adamec ◽  
Stanislav Nešpůrek ◽  
Josef Kuthan
Keyword(s):  
Reaction Kinetics ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Theoretical Data ◽  
Order Reaction ◽  
Bleaching Process ◽  
First Order ◽  
Photodegradation Products ◽  
Hypervalent Molecules

Molecular geometries of 2,4,4,6-tetraphenyl-4H-pyran (Ia), 4,4-(biphenyl-2,2e-diyl)-2,6-diphenyl-4H-pyran (Ib) and their heterocyclic isomers II-V were optimized by the PM3 method and used for the calculation of electronic absorption spectra by the CNDO/S-CI procedure. Comparison of the theoretical data with experimental UV-VIS absorption spectra made possible to select hypervalent molecules IIIa, IIIb, IVa and IVb being responsible for the photocolouration of 4H-pyrans Ia, Ib, while compounds Va, Vb, VI and VII come into account as possible photodegradation products. The bleaching process of the UV illuminated compound Ia is analyzed in terms of dispersive first-order reaction kinetics.

Kinetics and Mechanism of Hexachloroiridate(IV) Oxidation of Arsenic(III) in Acidic Perchlorate Solutions

1992 ◽  
Vol 57 (7) ◽  
pp. 1451-1458 ◽  
Author(s):  
Refat M. Hassan
Keyword(s):  
Ionic Strength ◽  
Fractional Order ◽  
Activation Parameters ◽  
Order Reaction ◽  
First Order Reaction ◽  
Intermediate Complex ◽  
Constant Ionic Strength ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Kinetics Of

The kinetics of oxidation of arsenic(III) by hexachloroiridate(IV) at lower acid concentrations and at constant ionic strength of 1.0 mol dm-3 have been investigated spectrophotometrically. A first-order reaction in [IrCl62-] and fractional order with respect to arsenic(III) have been observed. A kinetic evidence for the formation of an intermediate complex between the hydrolyzed arsenic(III) species and the oxidant was presented. The results showed that decreasing the [H+] is accompanied by an appreciable acceleration of the rate of oxidation. The activation parameters have been evaluated and a mechanism consistent with the kinetic results was suggested.

The Structure and Photochromism of 2,4,4,6-Tetraphenyl-4H-thiopyran

1992 ◽  
Vol 57 (6) ◽  
pp. 1326-1334 ◽  
Author(s):  
Jaroslav Vojtěchovský ◽  
Jindřich Hašek ◽  
Stanislav Nešpůrek ◽  
Mojmír Adamec
Keyword(s):  
Solid State ◽  
Uv Light ◽  
Order Reaction ◽  
Boat Conformation ◽  
X Rays ◽  
Exponential Time ◽  
First Order ◽  
Double Plane ◽  
The Mean ◽  
Independent Molecules

2,4,4,6-Tetraphenyl-4H-thiopyran, C29H22S, orthorhombic, Pna21, a = 17.980(4), b = 6.956(2), c = 34.562(11) Å, V = 4323(2) Å3, Z = 8, Dx = 1.237 g cm-3, F(000) = 1696, λ(CuKα) = 1.54184 A, μ = 1.372 mm-2, T = 294 K. The final R was 0.050 for the unique set of 3103 observed reflections. The central 4H-thiopyran ring forms a boat conformation for both symmetrically independent molecules with average boat angles 4.4(3) and 6.8(3)° at S and C(sp3), respectively. The mean planes of phenyls at the position 2 and 6 are turned from the double plane of 4H-thiopyran by 42.5(5) and 35.8(3)°, respectively. The investigated material undergoes a photochromic change in the solid state after irradiation with UV light or X-rays. The maximum of the new absorption band is situated at 564 nm. The non-exponential time dependence of photochromic bleaching is analysed in terms of a dispersive first-order reaction.

scholarly journals Synthesis, antibiotic structure–activity relationships, and cellulose dissolution studies of new room-temperature ionic liquids derived from lignin

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Shihong Liu ◽  
Michael Gonzalez ◽  
Celine Kong ◽  
Scott Weir ◽  
Aaron M. Socha
Keyword(s):  
Antibacterial Activity ◽  
Ionic Liquids ◽  
Room Temperature ◽  
Oxidation Products ◽  
Cellulose Dissolution ◽  
Melting Points ◽  
E Coli ◽  
Alkyl Chains ◽  
Renewable Feedstocks ◽  
Commodity Chemicals

Abstract Background Ionic liquids (ILs) are promising pretreatment solvents for lignocellulosic biomass, but are largely prepared from petroleum precursors. Benzaldehydes from depolymerized lignin, such as vanillin, syringaldehyde, and 4-methoxy benzaldehyde, represent renewable feedstocks for the synthesis of ionic liquids. We herein report syntheses of novel lignin-derived ionic liquids, with extended N-alkyl chains, and examine their melting points, cellulose dissolution capacities, and toxicity profiles against Daphnia magna and E. coli strain 1A1. The latter organism has been engineered to produce isoprenol, a drop-in biofuel and precursor for commodity chemicals. Results The new N,N-diethyl and N,N-dipropyl methyl benzylammonium ILs were liquids at room temperature, showing 75–100 °C decreased melting points as compared to their N,N,N-trimethyl benzylammonium analog. Extension of N-alkyl chains also increased antibacterial activity threefold, while ionic liquids prepared from vanillin showed 2- to 4-fold lower toxicity as compared to those prepared from syringaldehyde and 4-methoxybenzaldehyde. The trend of antibacterial activity for anions of lignin-derived ILs was found to be methanesulfonate < acetate < hydroxide. Microcrystalline cellulose dissolution, from 2 to 4 wt% after 20 min at 100 °C, was observed in all new ILs using light microscopy and IR spectroscopy. Conclusions Ionic liquids prepared from H-, S- and G-lignin oxidation products provided differential cytotoxic activity against E. coli and D. magna, suggesting these compounds could be tailored for application specificity within a biorefinery.

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