Kinetics of Catalytic Dehydration of 1-Pentanol

1993 ◽  
Vol 58 (8) ◽  
pp. 1874-1884 ◽  
Author(s):  
Iveta Vašutová ◽  
Milan Králik ◽  
Milan Hronec
Keyword(s):  
Experimental Data ◽  
Kinetic Data ◽  
Potassium Hydroxide ◽  
Molar Fraction ◽  
Space Velocity ◽  
Continuous Reactor ◽  
Alumina Catalyst ◽  
Direct Formation ◽  
Kinetics Of ◽  
Hydrolysis Of

Kinetic data of 1-pentanol dehydration on γ-alumina catalyst modified by potassium hydroxide were obtained using a continuous reactor with an internal recirculation. The conversion of 1-pentanol on this catalyst in the temperature range 300 - 390 °C and space velocity 1 - 8 kg (h kg)-1 (molar fraction of water in the feed was in the range 0 - 0.56) was 50 - 98% and the selectivity with respect to 1-pentene was 50 - 84%. The following six reactions have been taken into account to describe the catalytic dehydration of 1-pantanol: direct formation of 1-pentene from 1-pentanol, formation of bis(1-pentyl) ether from 1-pentanol, disproportionation of the ether to 1-pentanol and 1-pentene, formation of 1-pentene from the ether, isomerization of 1-pentene to 2-pentene and hydrolysis of the ether to 1-pentanol. Treatment of experimental data by Langmuir-Hinshelwood models showed that the model involving adsorption of 1-pentanol accompanied by dissociation is the most suitable one.

Untersuchung der alkalischen Hydrolyse des Benzoesäurebenzylesters in Wasser-Äthanol 1 : 1 / Study of the Basic Hydrolysis of Benzyl Benzoate in Water-Ethyl Alcohol 1:1

1974 ◽  
Vol 29 (11) ◽  
pp. 1697-1698 ◽  
Author(s):  
F. Mansilla ◽  
P. Martinez ◽  
J. Sancho
Keyword(s):  
Experimental Data ◽  
Reaction Mechanism ◽  
Order Rate Constant ◽  
Benzyl Benzoate ◽  
Conductometric Method ◽  
Alcohol Medium ◽  
Basic Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Water Alcohol

By using a conductometric method, the kinetics of the basic hydrolysis of benzyl benzoate in water-alcohol medium has been investigated. The second order rate constant follows the equation K = A exp {-E/RT} with A = 1.35·1010 l mol-1 min-1 and E = 14.5 kcal mol-1. A reaction mechanism is postulated, which is consistent with the experimental data.

scholarly journals Relationship of Exo-β-d-Galactofuranosidase Kinetic Parameters to the Number of Phosphodiesters in Penicillium fellutanum Peptidophosphogalactomannan: Enzyme Purification and Kinetics of Glycopeptide and Galactofuran Chain Hydrolysis

2001 ◽  
Vol 67 (10) ◽  
pp. 4648-4656 ◽  
Author(s):  
Brigitte A. Tuekam ◽  
Yong-Il Park ◽  
Clifford J. Unkefer ◽  
John E. Gander
Keyword(s):  
Kinetic Parameters ◽  
Kinetic Data ◽  
Inorganic Phosphate ◽  
Enzyme Purification ◽  
Degree Of Polymerization ◽  
Apparent Homogeneity ◽  
Relationship Of ◽  
Kinetics Of ◽  
Hydrolysis Of

ABSTRACT Extracellular Penicillium fellutanumexo-β-d-galactofuranosidase, with a mass of 70 kDa, was purified to apparent homogeneity. The enzyme was used to investigate the influence of phosphodiesters of the peptidophosphogalactomannans pP2GMii and pP25GMii(containing 2 and 25 phosphodiester residues, respectively, per mol of polymer) on the kinetic parameters of galactofuranosyl hydrolysis of these two polymers, of 1-O-methyl-β-d-galactofuranoside, and of two galactofuranooligosaccharides. The enzyme did not hydrolyze phosphorylated galactose residues of pP2GMii or pP25GMii. Thek cat/Km value for pP25GMii is 1.7 × 103M−1 s−1, that for 1-O-methyl-β-d-galactofuranoside is 1.1 × 104 M−1 s−1, that for pP2GMii is 1.7 × 10 4M−1 s−1, and those for 5-O-β-d-galactofuranooligosaccharides with degrees of polymerization of 3.4 and 5.5 are 1.7 × 105 and 4.1 × 105 M−1s−1, respectively. Variability in thek cat/Km values is due primarily to differences in Km values; thek −1/k 1 ratio likely provides the most influence on Km. k cat increases as the degree of polymerization of galactofuranosyl residues increases. Most of the galactofuranosyl and phosphocholine residues were removed by day 8 in vivo from pPxGMii added to day 3 cultures initiated in medium containing 2 mM phosphate but not from those initially containing 20 mM phosphate. The filtrates from day 9 cultures initiated in 2 mM inorganic phosphate in modified Raulin-Thom medium contained 0.2 mM inorganic phosphate and 2.2 U of galactofuranosidase ml−1h−1. No galactofuranosidase activity but 15 mM inorganic phosphate was found in filtrates from day 9 cultures initiated in 20 mM phosphate. In vivo the rate of galactofuranosyl hydrolysis of pPxGMii and of related polymers is proportional to thek cat/Km value of each polymer. The kinetic data show that thek cat/Km value increases as the number of phosphodiesters of pPxGMiidecreases, also resulting in an increase in the activity of exo-β-d-galactofuranosidase.

Calculation of isokinetic temperature of non-catalyzed hydrolysis of substituted 3-(N-methylcarbamoyl)-1,3-diphenyltriazenes

1981 ◽  
Vol 46 (4) ◽  
pp. 898-905 ◽  
Author(s):  
Oldřich Pytela ◽  
Miroslav Večeřa ◽  
Pavel Vetešník
Keyword(s):  
Experimental Data ◽  
Isokinetic Temperature ◽  
Reaction Series ◽  
Significance Level ◽  
Common Intersection ◽  
Reaction Constant ◽  
Straight Lines ◽  
The Given ◽  
Kinetics Of ◽  
Hydrolysis Of

Temperature dependence of kinetics of non-catalyzed hydrolysis of substituted 3-(N-methylcarbamoyl)-1,3-diphenyltriazines has been measured. An optimized calculation method has been suggested for calculation of the isokinetic temperature and the experimental data have been evaluated. In all the cases it has been found that the hypothesis of common intersection of the straight lines log k vs1/T is rejected at the significance level α = 0.05, but, within approximate validity of the isokinetic hypothesis the isokinetic relation can be considered to be fulfilled in the given reaction series. The change of the reaction constant ρ connected with the change of the reaction mechanism shows a statistically significant correspondence with the change of the isokinetic temperature.

Kinetics of the radical copolymerization of styrene and 2-methoxyethyl methacrylate

1983 ◽  
Vol 48 (9) ◽  
pp. 2656-2665 ◽  
Author(s):  
Jaroslav Stejskal ◽  
Dagmar Straková ◽  
Ondřej Procházka ◽  
Pavel Kratochvíl
Keyword(s):  
Experimental Data ◽  
Molecular Weight ◽  
Kinetic Data ◽  
Radical Copolymerization ◽  
Copolymer Composition ◽  
Monomer Mixture ◽  
Diffusion Controlled ◽  
Kinetics Of ◽  
Best Fit ◽  
Copolymerization Kinetics

Twenty low-conversion statistical copolymers of styrene and 2-methoxyethyl methacrylate with various composition were prepared. The dependence of the copolymer composition, molecular weight, initiation efficiency and other parameters on the composition of the monomer mixture is discussed. Kinetic data are correlated by means of various models of the copolymerization kinetics. The best fit with experimental data is provided by a diffusion-controlled termination model, especially its dyad variant suggested in this study.

Kinetics and mechanism of gold(III) incorporation into tetrakis(1-methylpyridium-4-yl)porphyrin in aqueous solution

2004 ◽  
Vol 08 (11) ◽  
pp. 1269-1275 ◽  
Author(s):  
Ahsan Habib ◽  
Masaaki Tabata ◽  
Ying Guang Wu
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Kinetic Data ◽  
Ph Dependence ◽  
Equilibrium Constants ◽  
Hydroxyl Group ◽  
Net Charge ◽  
First Order ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of the reaction of the tetrakis(1-methylpyridium-4-yl)porphyrin tetracation, [ H 2( TMPyP )]4+, with gold(III) ions were studied along with equilibria of gold(III) species in aqueous medium at 25°C, I = 0.10 M ( NaNO 3). The equilibrium constants for the formation of [ AuCl 4-n( OH ) n ]- ( n = 0,…,4), defined as β n = [ AuCl 4- n ( OH ) n ]- [ Cl -] n / [ AuCl 4-][ OH -] n were found to be that log β1 = 7.94 ± 0.03, log β2 = 15.14 ± 0.03, log β3 = 21.30 ± 0.05 and log β4 = 26.88 ± 0.05. The overall reaction was first order with respect to each of the total [ Au (III)] and [ H 2 TMPyP 4+]. On the basis of pH dependence on rate constants and the hydrolysis of gold(III), the rate expression can be written as d [ Au ( TMPyP )5+]/ dt = ( k 1[ AuCl 4-] + k2[ AuCl 3( OH )-] + k3[ AuCl 2( OH )2-] + k4[ AuCl ( OH )3-])[ H 2 TMPyP 4+], where k1, k2, k3 and k4 were found to be (2.16 ± 0.31) × 10-1, (6.56 ± 0.19) × 10-1, (1.07 ± 0.24) × 10-1, and (0.29 ± 0.21) × 10-1 M -1. s -1, respectively. The kinetic data revealed that the trichloromonohydroxogold(III) species, [ AuCl 3( OH )]-, is the most reactive. The higher reactivity of [ AuCl 3( OH )]- is explained by hydrogen bonding formation between the hydroxyl group of [ AuCl 3( OH )]- and the pyrrole hydrogen atom of [ H 2( TMPyP )]4+. Furthermore, applying the Fuoss equation to the observed rate constants at different ionic strengths, the apparent net charge of [ H 2( TMPyP )]4+ was calculated to be +3.5.

scholarly journals Evaluation of the extent of the binding site in human tissue kallikrein by synthetic substrates with sequences of human kininogen fragments

1995 ◽  
Vol 312 (1) ◽  
pp. 233-238 ◽  
Author(s):  
E Del Nery ◽  
J R Chagas ◽  
M A Juliano ◽  
E S Prado ◽  
L Juliano
Keyword(s):  
Human Tissue ◽  
Kinetic Data ◽  
Time Course ◽  
Tissue Kallikrein ◽  
Hydrolysis Time ◽  
Porcine Tissue ◽  
Enzyme Substrate ◽  
Substrate Side ◽  
Kinetics Of ◽  
Hydrolysis Of

We have synthesized internally quenched peptides spanning the Met379-Lys380 or Arg389-Ser390 bonds of human kininogen (hkng) that flank lysyl-bradykinin and have studied the kinetics of their hydrolysis by human tissue kallikrein. The kinetic data for the hydrolysis of the Met-Lys bond in substrates with an N-terminal extension showed that interactions up to position residue P10 contribute to the efficiency of cleavage. In contrast, there were no significant variations in the kinetic data for the hydrolysis of substrates with C-terminal extensions at sites P′4 to P′11. A similar pattern was observed for the cleavage of substrates containing an Arg-Ser bond because substrates extended up to residue P6 were hydrolysed with the highest kcat/Km values in the series, whereas those extended to P′11 on the C-terminal side had a lower susceptibility to hydrolysis. Time-course studies of hydrolysis by human and porcine tissue kallikreins of a Leu373 to Ile393 human kininogen fragment containing omicron-aminobenzoic acid (Abz) at the N-terminus and an amidated C-terminal carboxyl group Abz-Leu-Gly-Met-Ile-Ser-Leu-Met-Lys-Arg- Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg-Ser-Ser-Arg-Ile-NH2 (Abz-[Leu373-Ile393]-hkng-NH2) indicated that the cleavage of Met-Lys and Arg-Ser bonds in the same molecule occurs via the formation of independent enzyme-substrate complexes. The hydrolysis of Abz-F-R-S-S-R-Q-EDDnp [where EDDnp is N-(2,4-dinitrophenyl)ethylenediamine] and Abz-M-I-S-L-M-K-R-P-Q-EDDnp by human tissue kallikrein had maximal kcat/Km values at pH 9-9.5 for both substrates. The pH-dependent variations in this kinetic parameter were almost exclusively due to variations in kcat. A significant decrease in kcat/Km values was observed for the hydrolysis of Arg-Ser and Met-Lys bonds in the presence of 0.1 M NaCl. Because this effect was closely related to an increase in Km, it is likely that sodium competes with the positive charges of the substrate side chains for the same enzyme subsites.

scholarly journals The kinetics of hydrolysis of synthetic glucuronic esters and glucuronic ethers by bovine liver and Escherichia coli β-glucuronidase

1973 ◽  
Vol 133 (4) ◽  
pp. 789-795 ◽  
Author(s):  
J. Tomašić ◽  
D. Keglević
Keyword(s):  
Escherichia Coli ◽  
Kinetic Data ◽  
Glucuronic Acid ◽  
Bovine Liver ◽  
Kinetics Of Hydrolysis ◽  
Substrate Saturation ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Ylacetic Acid ◽  
Optimal Ph

1. The relative rates of hydrolysis of synthetically prepared β-d-glucuronic esters [aglycone: benzoic acid, veratroic (3,4-dimethoxybenzoic) acid, indol-3-ylacetic acid and ethylbutyric acid], and β-d-glucuronic ethers (aglycone: phenolphthalein, p-nitrophenol, 3,4-dimethoxyphenol, 3,4-dimethoxybenzyl alcohol) by commercial preparations of β-glucuronidase from bovine liver and Escherichia coli were investigated. The rates of hydrolysis of all compounds tested were followed by measuring the formation of glucuronic acid under conditions which do not affect the glycosidic ester bond. 2. The pH profiles of the substrates in reaction with the enzyme from both sources were determined, and substrate-saturation curves at the optimal pH for each substrate were constructed; double-reciprocal plots of activity against concentration were linear. 3. Comparison of kinetic data indicates that neither the type of sugar–aglycone linkage, nor the aglycone structure alone can explain the observed Km and Vmax. values. 4. α-d-Glucuronic esters of benzoic and veratroic acid resisted hydrolysis by β-glucuronidase from both sources.

scholarly journals STUDY OF THE ADSORPTION OF METHYLENE BLUE DYE IN CHITOSAN MICROSPHERES

2015 ◽  
Vol 12 (24) ◽  
pp. 28-34
Author(s):  
, Anna Karla dos Santos; ,, , PEREIRA ◽  
Gessiel Newton SCHEIDT ◽  
Lucas Samuel Soares SANTOS
Keyword(s):  
Experimental Data ◽  
Chemical Structure ◽  
Blue Dye ◽  
Maximum Adsorption Capacity ◽  
Methylene Blue Dye ◽  
Adsorption Model ◽  
Adsorption Sites ◽  
Pseudo Second Order ◽  
Kinetics Of ◽  
Hydrolysis Of

Chitosan is a polymer that can be used as adsorbent material. In this work, chitosan was synthesized via alkaline hydrolysis of chitin. The chemical structure was characterized by IR spectroscopy and the degree of deacetylation (% DG) of the acetamido groups present in the polymer matrix by neutralization titration. The most suitable adsorption model for analysis of experimental data was Langmuir. The maximum adsorption capacity of the microspheres (Ns) of chitosan was 3.36 x 10-6 mol g-1 adsorbent. The rate of adsorption is governed by the kinetics of the pseudo-second order, where the saturation of adsorption sites occurred after two hours of contact between the adsorbent and the adsorbate. By analyzing data across the isotherm model Dubinin-Radushkevich (DR) it was found that this process adsorption is physical in nature.

Hydrolysis Kinetics of Straw Biomass Catalyzed by Diluted Sulphuric Acid in the Present of Fe2+

2012 ◽  
Vol 550-553 ◽  
pp. 484-487 ◽  
Author(s):  
Chong Wen Jiang ◽  
Can Chen Bai ◽  
Hao Xiao
Keyword(s):  
Experimental Data ◽  
Sulfuric Acid ◽  
Kinetic Model ◽  
Acid Catalyst ◽  
Fermentable Sugars ◽  
Hydrolysis Kinetics ◽  
First Order ◽  
Sulfuric Acid Catalyst ◽  
Kinetics Of ◽  
Hydrolysis Of

This study focuses on kinetics of straw hydrolysis using sulfuric acid catalyst to produce fermentable sugars. The result shows the degradation of sugars is encountered during the hydrolysis of straw biomass. A consecutive first-order reactions kinetic model is proposed and the kinetic model well agrees with the experimental data. It turns out that rate of sugar formation and degradation is small at lower experimental temperature. The reactions rates constant k1 including the formation of sugar begins to increase rapidly when the Fe2+concentration increases from 0.125 to 0.500molL-1. However, the rate constant k2 relevant with the degradation of sugar varies unsensibly below 0.375molL-1 Fe2+and it is accelerated as the Fe2+concentration increases to 0.500molL-1. Thus the optimum yield is obtained at 0.375molL-1 Fe2+concentration.

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