scholarly journals Reinvestigation of the Deceptively Simple Reaction of Toluene with OH and the Fate of the Benzyl Radical: The “Hidden” Routes to Cresols and Benzaldehyde

2020 ◽  
Vol 124 (28) ◽  
pp. 5917-5930
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Nicola Tasinato ◽  
...  
Keyword(s):  
Simple Reaction ◽  
Benzyl Radical

Generality of a Speed Factor in Simple Reaction and Movement Time

1960 ◽  
Vol 11 (2) ◽  
pp. 123-128 ◽  
Author(s):  
William R. Pierson ◽  
Philip J. Rasch
Keyword(s):  
Movement Time ◽  
Simple Reaction ◽  
Speed Factor

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

Transient Kinetic and Thermodynamic Behaviour of Langmuir Adsorption in a Flow System

1999 ◽  
Vol 64 (4) ◽  
pp. 726-734 ◽  
Author(s):  
Miloslav Pekař ◽  
Josef Koubek
Keyword(s):  
Adsorption Equilibrium ◽  
Flow System ◽  
Adsorption Rate ◽  
Adsorption Behaviour ◽  
Transient Responses ◽  
Simple Reaction ◽  
Langmuir Adsorption ◽  
Thermodynamic Behaviour

Various kinetic pathways to the adsorption equilibrium in an isothermal differential bed of adsorbent are illustrated on several examples. Discussion is based on the computed transient responses of adsorption rate and distance from adsorption equilibrium to the start of adsorptive feed. It is shown that adsorption behaviour in flow system may not be smooth and very steep changes on the rate responses may appear. Even the simple reaction need not approach equilibrium smoothly but at a jump. The approach assuming "closeness to the equilibrium" should be used very carefully, in this case.

scholarly journals Manipulations of the Response-Stimulus Intervals as a Factor Inducing Controlled Amount of Reaction Time Intra-Individual Variability

2021 ◽  
Vol 11 (5) ◽  
pp. 669
Author(s):  
Paweł Krukow ◽  
Małgorzata Plechawska-Wójcik ◽  
Arkadiusz Podkowiński
Keyword(s):  
Reaction Time ◽  
Simple Reaction Time ◽  
Reaction Times ◽  
Reaction Time Task ◽  
Assessment Method ◽  
Individual Variability ◽  
Simple Reaction Time Task ◽  
Stimulus Interval ◽  
Simple Reaction ◽  
Response Stimulus

Aggrandized fluctuations in the series of reaction times (RTs) are a very sensitive marker of neurocognitive disorders present in neuropsychiatric populations, pathological ageing and in patients with acquired brain injury. Even though it was documented that processing inconsistency founds a background of higher-order cognitive functions disturbances, there is a vast heterogeneity regarding types of task used to compute RT-related variability, which impedes determining the relationship between elementary and more complex cognitive processes. Considering the above, our goal was to develop a relatively new assessment method based on a simple reaction time paradigm, conducive to eliciting a controlled range of intra-individual variability. It was hypothesized that performance variability might be induced by manipulation of response-stimulus interval’s length and regularity. In order to verify this hypothesis, a group of 107 healthy students was tested using a series of digitalized tasks and their results were analyzed using parametric and ex-Gaussian statistics of RTs distributional markers. In general, these analyses proved that intra-individual variability might be evoked by a given type of response-stimulus interval manipulation even when it is applied to the simple reaction time task. Collected outcomes were discussed with reference to neuroscientific concepts of attentional resources and functional neural networks.

A new synthetic method for an acromelic acid analog, a potent neuroexcitatory kainoid amino acid, via photoinduced benzyl radical cyclization

2002 ◽  
Vol 43 (43) ◽  
pp. 7777-7780 ◽  
Author(s):  
Satoshi Itadani ◽  
Shigeyuki Takai ◽  
Chieko Tanigawa ◽  
Kimiko Hashimoto ◽  
Haruhisa Shirahama
Keyword(s):  
Amino Acid ◽  
Radical Cyclization ◽  
Synthetic Method ◽  
Benzyl Radical ◽  
Acid Analog

scholarly journals Indicators of Targeted Physical Fitness in Judo and Jujutsu—Preliminary Results of Research

2021 ◽  
Vol 18 (8) ◽  
pp. 4347
Author(s):  
Wojciech J. Cynarski ◽  
Jan Słopecki ◽  
Bartosz Dziadek ◽  
Peter Böschen ◽  
Paweł Piepiora
Keyword(s):  
Reaction Time ◽  
Visual Stimulation ◽  
Intrinsic Value ◽  
Reaction Times ◽  
Arithmetic Means ◽  
Simple Reaction ◽  
Martial Art ◽  
Student’S T ◽  
Pearson Correlations ◽  
Student’S T Test

(1) Study aim: This is a comparative study for judo and jujutsu practitioners. It has an intrinsic value. The aim of this study was to showcase a comparison of practitioners of judo and a similar martial art jujutsu with regard to manual abilities. The study applied the measurement of simple reaction time in response to a visual stimulus and handgrip measurement. (2) Materials and Methods: The group comprising N = 69 black belts from Poland and Germany (including 30 from judo and 39 from jujutsu) applied two trials: “grasping of Ditrich rod” and dynamometric handgrip measurement. The analysis of the results involved the calculations of arithmetic means, standard deviations, and Pearson correlations. Analysis of the differences (Mann–Whitney U test) and Student’s t-test were also applied to establish statistical differences. (3) Results: In the test involving handgrip measurement, the subjects from Poland (both those practicing judo and jujutsu) gained better results compared to their German counterparts. In the test involving grasping of Ditrich rod, a positive correlation was demonstrated in the group of German judokas between the age and reaction time of the subjects (rxy = 0.66, p < 0.05), as well as in the group of jujutsu subjects between body weight and the reaction time (rxy = 0.49, p < 0.05). A significant and strong correlation between handgrip and weight was also established for the group of German judokas (rxy = 0.75, p < 0.05). In Polish competitors, the correlations were only established between the age and handgrip measurements (rxy = 0.49, p < 0.05). (4) Conclusions: Simple reaction times in response to visual stimulation were shorter in the subjects practicing the martial art jujutsu. However, the statement regarding the advantage of the judokas in terms of handgrip force was not confirmed by the results.

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