Benzyl Cation Stabilized by Metal Complexation. Relative Stability of Coordinated Methylene Arenium, π-Benzylic, and σ-Benzylic Structures

2013 ◽  
Vol 32 (17) ◽  
pp. 4813-4819 ◽  
Author(s):  
Elena Poverenov ◽  
Irena Efremenko ◽  
Gregory Leitus ◽  
Jan M. L. Martin ◽  
David Milstein
Keyword(s):  
Relative Stability ◽  
Metal Complexation ◽  
Benzyl Cation

Equilibrium Studies of Binary and Ternary Complexes of Palladium(II) Involving Amino Acids

1993 ◽  
Vol 58 (5) ◽  
pp. 1103-1108 ◽  
Author(s):  
Mohamed M. Shoukry ◽  
Eman M. Shoukry
Keyword(s):  
Amino Acids ◽  
Relative Stability ◽  
Ternary Complex ◽  
Formation Constants ◽  
Ternary Complexes ◽  
Conductivity Measurements ◽  
Equilibrium Studies ◽  
Binary And Ternary Complexes ◽  
Binary Complexes

The formation constants of the binary and ternary complexes of palladium(II) with diethylenetriamine and amino acids as ligands have been determined potentiometrically at 25 °C in 0.1 M NaNO3 solution. The relative stability of each ternary complex was compared with that of the corresponding binary complexes in terms of ∆logK values. The mode of chelation was ascertained by conductivity measurements.

scholarly journals A Novel Index (RI) to Evaluate the Relative Stability of Soils Using Ultrasonic Agitation

2021 ◽  
Vol 13 (8) ◽  
pp. 4229
Author(s):  
Fakher Abbas ◽  
Fang Lin ◽  
Zhaolong Zhu ◽  
Shaoshan An
Keyword(s):  
Relative Stability ◽  
Characteristic Curve ◽  
Geometric Mean ◽  
Relative Strength ◽  
Soil Stability ◽  
Dispersion Energy ◽  
Ultrasonic Agitation ◽  
Mean Weight Diameter ◽  
Change In Mean ◽  
Wet Sieving

As soil stability is a complex phenomenon, various methods and indexes were introduced to assess the strength of soils. Because of the limitations of different stability methods and indexes (including wet sieving-based), we aimed to presents a relative stability index (RI) that was based on the estimated components of the soil overall disruptive characteristic curve (SODC): (1) soil disruption constant (Ki, that is based upon dispersion energy of soils); (2) resulting change in mean weight diameter (ΔMWD). To evaluate the effectiveness and limitations of RI as well as to compare it with classical soil stability indexes of mean weight diameter (MWD) and geometric mean diameter (GMD). Ultrasonic agitation (UA) along with a wet sieving method (followed by dry sieving) was applied against four different soils named on the basis of sample location, Qingling soil (QL), Guanzhong soil (GZ), Ansai soil (AS), and Jingbian soil (JB). To evaluate the relative strength of soils at different applied energies (increase in sonication duration usually resulted in increased input energy and temperature of soil–water suspension), soils were subjected to six sonication durations (0, 30, 60, 120, 210, and 300 s) with a fixed (and exact) initial amplitude and temperature. Output energy was calculated based on the amplitude and temperature of the suspension, vessel, and system. The most abrupt and maximum disruption of soil aggregates was observed at a dispersion energy level of 0–200 J g−1. The MWD value of surface and subsurface ranged between 0.58 to 0.15 mm and 0.37 to 0.17 mm, respectively, while GMD was ranged from 0.14 to 0.33 mm overall. The results for MWD and GMD showed a similar trend. MWD and GMD showed more strong associations with physicochemical characteristics of soil than RI. A non-significant correlation was found between RI and MWD/GMD. Contrary to MWD and GMD, RI was significantly positively correlated with sand content; this finding indicated the influential role of sand in assessing the soil’s relative strength. The results indicated that JB soil possessed the least MWD and GMD but proved to be relatively stable because of having the highest RI value.

A Convenient Protecting Group for Uridine Ureido Nitrogen: (4,4′-Bisfluorophenyl)methoxymethyl Group

Synthesis ◽  
2021 ◽  
Author(s):  
Michio Kurosu ◽  
Katsuhiko Mitachi ◽  
David Mingle
Keyword(s):  
Chemical Transformation ◽  
Relative Stability ◽  
Protecting Group

Abstract(4,4′-Bisfluorophenyl)methoxymethyl (BFPM) group of uridine ureido nitrogen shows good relative stability in a variety of chemical transformation reactions for uridine. The BFPM group can be cleaved by 2% of TFA in CH2Cl2 without affecting the Boc group.

Photoelectron Spectroscopy and Theoretical Study of AlnC5-/0 (n = 1-5) clusters: Structural Evolution, Relative Stability of Star-Like Cluster, and Planar Tetracoordinate Carbon Structure

2021 ◽  
Author(s):  
Chao-Jiang Zhang ◽  
Peng Wang ◽  
Xi-Ling Xu ◽  
Hong-Guang Xu ◽  
Weijun Zheng
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Relative Stability ◽  
Theoretical Study ◽  
Structural Evolution ◽  
Carbon Structure ◽  
Anion Photoelectron Spectroscopy

The AlnC5- (n = 1-5) clusters were detected in the gas-phase and were investigated by mass-selected anion photoelectron spectroscopy. The structures of AlnC5-/0 (n = 1-5) were explored by theoretical...

scholarly journals Revisiting the mechanism of β-O-4 bond cleavage during acidolysis of lignin VII: acidolyses of non-phenolic C6-C2-type model compounds using HBr, HCl and H2SO4, and a proposal on the characteristic action of Br− and Cl−

2020 ◽  
Vol 66 (1) ◽  
Author(s):  
Qiaoqiao Ye ◽  
Tomoya Yokoyama
Keyword(s):  
Model Compound ◽  
Bond Cleavage ◽  
Type Model ◽  
Enol Ether ◽  
Lignin Model Compound ◽  
Benzyl Cation ◽  
Acid Type ◽  
Unstable Compound ◽  
Lignin Model ◽  
Acidolysis Reaction

AbstractA non-phenolic C6-C2-type lignin model compound with the β-O-4 bond, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)ethanol (I), was acidolyzed in aqueous 82% 1,4-dioxane containing HBr, HCl, or H2SO4 with a concentration of 0.2 mol/L at 85 ℃ to examine the differences between these acidolyses. Compound I primarily converted to an enol ether compound, 1-(2-methoxyphenoxy)-2-(3,4-dimethoxyphenyl)ethene (II), via the benzyl cation followed by acidolytic β-O-4 bond cleavage regardless of the acid-type, although the disappearance rates of compound I were remarkably different (HBr > HCl >> H2SO4). Acidolyses of compound II using these acids under the same conditions showed a similar tendency, but the rate differences were much smaller than in the acidolyses of compound I. Acidolyses of the α-methyl-etherified derivative of compound I (I-α-OMe) using these acids under the same conditions suggested that the formation rates of the benzyl cation from compound I-α-OMe (also from compound I) are not largely different between the acidolyses using these acids, but those of compound II from the benzyl cation are remarkably different. Acidolysis of the α-bromo-substituting derivative of compound I (I-α-Br) using HBr under the same conditions showed a characteristic action of Br¯ in the acidolysis. Br¯ adds to the benzyl cation generated from compound I or I-α-OMe to afford unstable compound I-α-Br, resulting in acceleration of the formation of compound II and of the whole acidolysis reaction.

Festival Glasperlenspiel, Estonia. Tartu 9–15 July 2020 and Saaremaa 15–18 July 2020.

Tempo ◽  
2020 ◽  
Vol 75 (295) ◽  
pp. 95-96
Author(s):  
Lauri Supponen
Keyword(s):  
Relative Stability ◽  
25Th Anniversary ◽  
Music Festivals ◽  
Public Events

Although 2020 will mostly be remembered as a period of hiatus for music festivals, a period of relative stability during the summer in Estonia enabled the festival Glasperlenspiel to hold most of its 25th anniversary programme. The strict restrictions on travel and gatherings (limited to 2 people in March) were eased in May when Covid cases in Estonia went under 10 per 100,000. Travel from Finland opened without restrictions on June 15, and the festival organisers knew in May that public events would again be allowed as of July 1. They were cutting it rather close, as until 30 June public events were completely prohibited.

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