scholarly journals Experimental Evidence that Halogen Bonding Catalyzes the Heterogeneous Chlorination of Alkenes in Submicron Liquid Droplets

2021 ◽  
Author(s):  
Meirong Zeng ◽  
Kevin Roger Wilson
Keyword(s):  
Experimental Evidence ◽  
Halogen Bonding ◽  
Liquid Droplets ◽  
Elementary Steps ◽  
Kinetics Of

A key challenge in predicting the multiphase chemistry of aerosols and droplets is connecting reaction probabilities, observed in an experiment, with the kinetics of individual elementary steps that control the...

The kinetics of isomerization of allylbenzene homogeneously catalysed by palladium(II) in acetic acid

1973 ◽  
Vol 26 (12) ◽  
pp. 2635 ◽  
Author(s):  
BI Cruikshank ◽  
NR Davies
Keyword(s):  
Acetic Acid ◽  
Catalytic Activity ◽  
Experimental Evidence ◽  
Active Catalyst ◽  
Bimolecular Reaction ◽  
Equilibrium System ◽  
Constant Concentration ◽  
First Order ◽  
Rate Determining Step ◽  
Kinetics Of

The changes in the kinetics observed during the isomerization of allylbenzene catalysed by palladium(II) are interpreted in terms of the slow formation of a hydrido complex of palladium(II) which subsequently attains a constant concentration in an equilibrium system. The kinetics during these phases are shown to be consistent with first-order dependence on the concentration of an active catalyst formed in a bimolecular reaction from a mononuclear palladium(II) complex and with a regenerative hydrido-π-alkene-σ-alkyl mechanism of isomerization. The hypothesis that a further stage in the kinetics reflects a change in the rate determining step to one involving alkene displacement from the catalyst is supported by the experimental evidence. The concentration of active catalyst is shown not to fall appreciably until all the allylbenzene has undergone isomerization, but thereafter there is a slow reduction of catalytic activity which is not completely restored by the addition of further allylbenzene. It is suggested that the slow formation of a π-allylic complex is responsible.

scholarly journals DOES THE KINETICS OF TRYPSIN DIGESTION DEPEND ON THE FORMATION OF A COMPOUND BETWEEN ENZYME AND SUBSTRATE

1922 ◽  
Vol 4 (5) ◽  
pp. 487-509 ◽  
Author(s):  
John H. Northrop
Keyword(s):  
Experimental Evidence ◽  
Substrate Concentration ◽  
Relative Velocity ◽  
Mass Action ◽  
Law Of Mass Action ◽  
Rate Of Hydrolysis ◽  
Gelatin Concentration ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Substrate Concentrations

1. The velocity of hydrolysis of gelatin by trypsin increases more slowly than the gelatin concentration and finally becomes nearly independent of the gelatin concentration. The relative velocity of hydrolysis of any two substrate concentrations is independent of the quantity of enzyme used to make the comparison. 2. The rate of hydrolysis is independent of the viscosity of the solution. 3. The percentage retardation of the rate of hydrolysis by inhibiting substances, is independent of the substrate concentration. 4. There is experimental evidence that the enzyme and inhibiting substance are combined to form a widely dissociated compound. 5. If the substrate were also combined with the enzyme, an increase in the substrate concentration should affect the equilibrium between the enzyme and the inhibiting substance. This is not the case. 6. The rate of digestion of a mixture of casein and gelatin is equal to the sum of the rates of hydrolysis of the two substances alone, as it should be if the rate is proportional to the concentration of free enzyme. This contradicts the saturation hypothesis. 7. If the reaction is followed by determining directly the change in the substrate concentration, it is found that this change agrees with the law of mass action; i.e., the rate of digestion is proportional to the substrate concentration.

The Wicking Kinetics of Liquid Droplets into Yarns

2001 ◽  
Vol 71 (10) ◽  
pp. 862-869 ◽  
Author(s):  
Xuemin Chen ◽  
Konstantin G. Kornev ◽  
Yash K. Kamath ◽  
Alexander V. Neimark
Keyword(s):  
Liquid Droplets ◽  
Kinetics Of

AM1 calculational and experimental evidence that a β-nitroxyl group significantly enhances the thermodynamic and kinetic acidities of ketones

1994 ◽  
Vol 72 (11) ◽  
pp. 2348-2350 ◽  
Author(s):  
Nick Henry Werstiuk ◽  
Chandra Deo Roy
Keyword(s):  
Experimental Evidence ◽  
Gas Phase ◽  
Carbonyl Group ◽  
Rate Constants ◽  
Second Order ◽  
Nitroxyl Group ◽  
Order Rate ◽  
Kinetics Of

The kinetics of NaOD-catalysed H/D exchange of 3,3,5,5-tetramethylcyclohexanone (1), 1-hydroxy-4-oxo-2,2,6,6-tetrame-thylpiperidine (2), 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl (3), 9-hydroxynorpseudopelletierine (4), and norpseudopelle-tierine-9-oxyl (5) have been studied in 60:40 dioxane–D2O(v/v) at 25.0 °C. The second-order rate constants are 9.20 × 10−3, 6.39 × 10−2, 1.59, 2.20 × 10−2, and 5.67 × 10−1 L mol−1 s−1 for 1, 2, 3, 4, and 5, respectively. Gas-phase enthalpies of ionization (the values are 363.0, 359.4, 352.0, 360.7, and 354.1 kcal mol−1 for 1, 2, 3, 4, and 5, respectively) calculated with AM1 correlate with the relative rates of enolization. Thus replacement of the β-hydroxylamino groups of 2 and 4 with a nitroxyl group produces sizable increases in the kinetic and thermodynamic acidities of the hydrogens α to the carbonyl group.

scholarly journals THE ORIGIN AND TURNOVER OF MONONUCLEAR CELLS IN PERITONEAL EXUDATES IN RATS

1966 ◽  
Vol 124 (2) ◽  
pp. 241-254 ◽  
Author(s):  
Alvin Volkman
Keyword(s):  
Bone Marrow ◽  
Experimental Evidence ◽  
Thoracic Duct ◽  
Mononuclear Cells ◽  
Tritiated Thymidine ◽  
Thoracic Duct Lymph ◽  
Duct Lymph ◽  
Kinetics Of

Tritiated thymidine-labeling data in individual and parabiotic rats showed that macrophages in peritoneal exudates were derived from cells in the blood which were the progeny of rapidly and continuously proliferating precursors. The characteristics of this population identify them with free macrophages studied in other sites; similarly, they can be obtained from transfused bone marrow. Cells in the exudates which were morphologically indistinguishable from small lymphocytes were also found to have the labeling features of a rapidly proliferating population in contrast with the known kinetics of the majority of small lymphocytes in blood and thoracic duct lymph. However, experimental evidence indicated that the lymphocytelike exudate cells had emigrated from the blood and that bone marrow was a source of their precursors. These findings support the concept of the heterogeneity of lymphocytes. The possible relationships among the mononuclear cells is discussed.

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