Bromination of saturated aliphatic ketones in an acidic medium: effects of structure on apparent rate constants for enolization and for bromination of the enol

1969 ◽  
pp. 292 ◽  
Author(s):  
J. E. Dubois ◽  
J. Toullec
Keyword(s):  
Rate Constants ◽  
Acidic Medium ◽  
Medium Effects ◽  
Aliphatic Ketones

Kinetics of hydrolysis of peroxodisulphate ions in acidic medium to peroxomonosulphuric acid

1981 ◽  
Vol 46 (5) ◽  
pp. 1229-1236 ◽  
Author(s):  
Jan Balej ◽  
Milada Thumová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Acidic Medium ◽  
Measured Data ◽  
Molar Ratios ◽  
Starting Solution ◽  
Kinetics Of Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

The rate of hydrolysis of S2O82- ions in acidic medium to peroxomonosulphuric acid was measured at 20 and 30 °C. The composition of the starting solution corresponded to the anolyte flowing out from an electrolyser for production of this acid or its ammonium salt at various degrees of conversion and starting molar ratios of sulphuric acid to ammonium sulphate. The measured data served to calculate the rate constants at both temperatures on the basis of the earlier proposed mechanism of the hydrolysis, and their dependence on the ionic strength was studied.

Réactivité nucléophile des cyclanones: influence de la stéréochimie cis/trans en série bicyclique

1982 ◽  
Vol 60 (18) ◽  
pp. 2355-2357 ◽  
Author(s):  
C. Agami ◽  
T. Rizk ◽  
R. Durand ◽  
P. Geneste
Keyword(s):  
Trans Isomer ◽  
Rate Constants ◽  
Nucleophilic Addition ◽  
Acidic Medium ◽  
Conformation Equilibrium ◽  
Bicyclic Ketones

The relative reactivities of a number of cis/trans pairs of bicyclic ketones in the 1- and 2-decalone series (2-decalone; 10-methyl-2-decalone; 9-methyl-1-decalone; and 3,10-dimethyl-2-decalone) have been studied for the nucleophilic addition of hydroxylamine in acidic medium. The results obtained as well as the rate constants for neutral or acid catalysed addition always reveal a slight preference for the trans-isomer (× 2.4). This result agrees with the proposal that preferential equatorial attack of a nucleophile is caused by conformational factors related to a steroid [Formula: see text] non-steroid conformation equilibrium in the cis-isomers. [Journal Translation]

Rate constants for the reaction of the hydrogen atom with aliphatic ketones in water

1997 ◽  
Vol 75 (8) ◽  
pp. 1114-1119 ◽  
Author(s):  
Stephen P. Mezyk ◽  
Annett Lossack ◽  
David M. Bartels
Keyword(s):  
Hydrogen Atom ◽  
Rate Constants ◽  
Radical Scavenger ◽  
Hydrogen Atoms ◽  
Paramagnetic Resonance ◽  
Kinetic Measurements ◽  
Aliphatic Ketones ◽  
Hydroxyl Radical Scavenger ◽  
Free Induction ◽  
Electron Paramagnetic

Arrhenius parameters for the reaction of hydrogen atoms with 3-methyl-2-butanone, 3-pentanone, cyclopentanone, 4-methyl-2-pentanone, and 2-butanone in aqueous solution have been directly calculated from electron paramagnetic resonance free induction decay (FID) attenuation measurements. For these compounds, absolute scavenging rate constants at 25.0 °C of (8.84 ± 0.26) × 107, (4.20 ± 0.15) × 107, (4.91 ± 0.28) × 107, (3.25 ± 0.27) × 107, and (2.20 ± 0.32) × 107 dm3 mol−1 s−1, with corresponding activation energies of 17.43 ± 0.29, 20.69 ± 0.31, 18.73 ± 0.36, 22.24 ± 0.80, and 22.30 ± 1.04 kJ mol−1 were determined, respectively. Competition kinetic measurements based on total H2 yields have established that for all of these ketones the dominant hydrogen atom reaction path is by •H atom abstraction. The new activation energy for 2-butanone is much lower than the previously reported value of 40.1 ± 0.7 kJ mol−1 with this difference attributed to interfering reactions from the added bromide previously used as a hydroxyl radical scavenger. Keywords: Arrhenius, kinetics, hydrogen atom, aqueous, ketones.

Kinetic medium effects. II. Hydrolysis of esters in electrolyte solutions

1965 ◽  
Vol 18 (12) ◽  
pp. 1943 ◽  
Author(s):  
PT McTigue ◽  
AR Watkins
Keyword(s):  
Rate Constants ◽  
Butyl Acetate ◽  
Aqueous Electrolyte ◽  
Aqueous Media ◽  
Electrolyte Solutions ◽  
Hydration Numbers ◽  
Medium Effects ◽  
Hydrolysis Of Esters ◽  
Hydrolysis Of ◽  
Methyl Chloroacetate

Rate constants have been measured for the acid-catalysed hydrolyses of t-butyl acetate and methyl chloroacetate in various aqueous electrolyte solutions; the activity coefficients of the esters in these electrolyte solutions have also been measured. The results are used to test a recently proposed method of determining transition state hydration numbers for reactions in aqueous media.

Gender Differences in the Mental Rotations Test (MRT) Are Not Due to Task Complexity

2008 ◽  
Vol 29 (3) ◽  
pp. 130-133 ◽  
Author(s):  
Corinna Titze ◽  
Martin Heil ◽  
Petra Jansen
Keyword(s):  
Gender Differences ◽  
Mental Rotation ◽  
Task Complexity ◽  
Time Constraints ◽  
Medium Effects ◽  
Performance Factors ◽  
Mental Rotations ◽  
Sufficient Power ◽  
Forced Choice Tasks ◽  
Choice Tasks

Gender differences are one of the main topics in mental rotation research. This paper focuses on the influence of the performance factor task complexity by using two versions of the Mental Rotations Test (MRT). Some 300 participants completed the test without time constraints, either in the regular version or with a complexity reducing template creating successive two-alternative forced-choice tasks. Results showed that the complexity manipulation did not affect the gender differences at all. These results were supported by a sufficient power to detect medium effects. Although performance factors seem to play a role in solving mental rotation problems, we conclude that the variation of task complexity as realized in the present study did not.

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