Effect of counter-ion in the anionic polymerization of styrene in cyclohexane

1968 ◽  
Vol 46 (16) ◽  
pp. 2711-2713 ◽  
Author(s):  
J. E. L. Roovers ◽  
S. Bywater
Keyword(s):  
Anionic Polymerization ◽  
Rate Constants ◽  
Ion Pairs ◽  
Propagation Rate ◽  
Counter Ion ◽  
Counter Ions

The propagation reaction in the anionic polymerization of styrene has been studied in cyclohexane with the counter-ions: K, Rb, and Cs. Some association of the ion-pairs was found with K. Absolute propagation rate constants were determined in the three cases. Some experiments were carried out in benzene–cyclohexane mixtures to check that the results were consistent with those previously observed in benzene.

Anionic polymerization of styrene in oxepane (hexamethylene oxide)•counter-ion, sodium

1970 ◽  
Vol 48 (13) ◽  
pp. 2031-2034 ◽  
Author(s):  
G. Löhr ◽  
S. Bywater
Keyword(s):  
Dielectric Constant ◽  
Dipole Moment ◽  
Rate Constant ◽  
Wide Temperature Range ◽  
Anionic Polymerization ◽  
Propagation Rate ◽  
Ion Pair ◽  
Temperature Range ◽  
Counter Ion ◽  
Propagation Rate Constant

The propagation reaction in the anionic polymerization of styrene in oxepane has been studied as a function of temperature and concentration of polystyrylsodium. Conductance measurements on polystyrylsodium were also made together with determinations of density, viscosity, dielectric constant, and dipole moment of oxepane itself. The measurements enabled the propagation rate constant to be determined of the polystyryl anion at 30 °C and of the ion-pair over a wide temperature range. The results have been compared with those obtained in tetrahydrofuran and tetrahydropyran.

Fluorescent organic ion pairs based on berberine: counter-ion effect on the formation of particles and on the uptake by colon cancer cells

RSC Advances ◽  
2015 ◽  
Vol 5 (2) ◽  
pp. 1181-1190 ◽  
Author(s):  
Marine Soulié ◽  
Céline Frongia ◽  
Valérie Lobjois ◽  
Suzanne Fery-Forgues
Keyword(s):  
Colon Cancer ◽  
Cancer Cells ◽  
Ion Pairs ◽  
Colon Cancer Cells ◽  
Counter Ion ◽  
Counter Ions ◽  
In Cells

Counter-ions modulate the fluorescence of berberine ion pairs in cells, this process being possibly linked to the formation of nanoparticles.

scholarly journals Rate and Product Studies with 1-Adamantyl Chlorothioformate under Solvolytic Conditions

2021 ◽  
Vol 22 (14) ◽  
pp. 7394
Author(s):  
Kyoung Ho Park ◽  
Mi Hye Seong ◽  
Jin Burm Kyong ◽  
Dennis N. Kevill
Keyword(s):  
Rate Constants ◽  
Isotope Effects ◽  
Ion Pairs ◽  
Carbonyl Sulfide ◽  
Activation Parameters ◽  
Chloride Ions ◽  
Reaction Channels ◽  
Decomposition Pathway ◽  
Solvent Isotope ◽  
Solvent Isotope Effects

A study was carried out on the solvolysis of 1-adamantyl chlorothioformate (1-AdSCOCl, 1) in hydroxylic solvents. The rate constants of the solvolysis of 1 were well correlated using the Grunwald–Winstein equation in all of the 20 solvents (R = 0.985). The solvolyses of 1 were analyzed as the following two competing reactions: the solvolysis ionization pathway through the intermediate (1-AdSCO)+ (carboxylium ion) stabilized by the loss of chloride ions due to nucleophilic solvation and the solvolysis–decomposition pathway through the intermediate 1-Ad+Cl− ion pairs (carbocation) with the loss of carbonyl sulfide. In addition, the rate constants (kexp) for the solvolysis of 1 were separated into k1-Ad+Cl− and k1-AdSCO+Cl− through a product study and applied to the Grunwald–Winstein equation to obtain the sensitivity (m-value) to change in solvent ionizing power. For binary hydroxylic solvents, the selectivities (S) for the formation of solvolysis products were very similar to those of the 1-adamantyl derivatives discussed previously. The kinetic solvent isotope effects (KSIEs), salt effects and activation parameters for the solvolyses of 1 were also determined. These observations are compared with those previously reported for the solvolyses of 1-adamantyl chloroformate (1-AdOCOCl, 2). The reasons for change in reaction channels are discussed in terms of the gas-phase stabilities of acylium ions calculated using Gaussian 03.

4-(Piperidin-1-yl)pyridinium hexafluorophosphate at 150 K

2003 ◽  
Vol 59 (11) ◽  
pp. o622-o624 ◽  
Author(s):  
Bruce D. James ◽  
Siti Mutrofin ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Hydrogen Bonds ◽  
Structural Characterization ◽  
Title Compound ◽  
Ion Pairs ◽  
Piperidine Ring ◽  
Torsion Angles ◽  
Compound C ◽  
Counter Ions

Structural characterization of the title compound, C10H15N2 +·PF6 −, shows it to be ionic, with the pyridine rather than the piperidine N atom being protonated and forming hydrogen bonds to the counter-ions, resulting in two independent ion pairs. A number of unusual features are noted, in particular the remarkably close inter-ring hydrogen contacts [1.97 (3)–2.00 (3) Å] and the considerable differences in the pair of cations, in respect of the torsion angles within the piperidine ring involving the bonds to either side of the N atom.

Isotope effects and activation parameters for the proton transfer reaction from 1-(4-nitrophenyl)-1-nitroethane to free anions and ion pairs of cesium n-propoxide in n-propanol solvent

1986 ◽  
Vol 64 (6) ◽  
pp. 1021-1025 ◽  
Author(s):  
Arnold Jarczewski ◽  
Grzegorz Schroeder ◽  
Przemyslaw Pruszynski ◽  
Kenneth T. Leffek
Keyword(s):  
Proton Transfer ◽  
Rate Constants ◽  
Isotope Effects ◽  
Ion Pairs ◽  
Activation Parameters ◽  
Solvation Shell ◽  
Ion Pair ◽  
Initial State ◽  
Free Ion ◽  
Deuteron Transfer

Rate constants for the proton and deuteron transfer from 1-(4-nitrophenyl)-1-nitroethane to cesium n-propoxide in n-propanol have been measured under pseudo-first-order conditions with an excess of base for four temperatures between 5 and 35 °C. Using literature values of the fraction of cesium n-propoxide ion pairs that are dissociated into free ions, separate second-order rate constants for the proton and deuteron transfer to the ion pair and to the free ion have been calculated. The cesium n-propoxide ion pair is about 2.8 times more reactive than the free n-propoxide ion. The primary kinetic isotope effects for the two reactions are the same (kH/kD = 6.1–6.3 at 25 °C) within experimental error. The enthalpy of activation is smaller for the ion-pair reaction and the entropy of activation more negative than for the free-ion reaction. For proton transfer, ΔH±ion pair = 8.3 ± 0.2 kcal mol−1, ΔH±ion = 9.6 ± 1.0 kcal mol−1, ΔS±ion pair = −12.3 ± 0.6 cal mol−1 deg−1, ΔS±ion = −10.1 ± 3.4 cal mol−1 deg−1. The greater reactivity of the ion pair relative to the free ion is interpreted in terms of the weaker solvation shell of the ion pair in the initial state.

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