Iodine-Catalyzed Isomerization of Olefins. III. Kinetics of the Geometrical Isomerization of Butene-2 and the Rate of Rotation About a Single Bond

1965 ◽  
Vol 87 (3) ◽  
pp. 468-476 ◽  
Author(s):  
Sidney W. Benson ◽  
Kurt W. Egger ◽  
David M. Golden
Keyword(s):  
Single Bond ◽  
Geometrical Isomerization ◽  
Kinetics Of

The Racemization and Geometrical Isomerization of Oxiranes

1972 ◽  
Vol 50 (3) ◽  
pp. 428-433 ◽  
Author(s):  
Helen H. J. MacDonald ◽  
Robert J. Crawford
Keyword(s):  
Optically Active ◽  
Oxirane Ring ◽  
Geometrical Isomerization ◽  
Kinetics Of ◽  
Cis Isomer

Optically active trans-2-phenyl-3-p-tolyloxirane and cis-2-phenyl-3-p-tolyloxirane were synthesized and the kinetics of their racemization and geometrical isomerization were studied.The slower rate of racemization of the cis-isomer compared with that of the trans is attributed to the conrotatory opening of the oxirane ring.

The kinetics of polysulphone formation IV. The isomerization of cis - and trans -2-butene accompanying polysulphone formation

1955 ◽  
Vol 229 (1179) ◽  
pp. 525-536 ◽  
Keyword(s):  
Sulphur Dioxide ◽  
Kinetic Studies ◽  
Ideal Liquid ◽  
Isomerization Reaction ◽  
Kcal Mole ◽  
Geometrical Isomerization ◽  
Ceiling Temperature ◽  
Liquid Sulphur ◽  
Cis And Trans ◽  
Kinetics Of

It has been shown by infra-red spectroscopic measurements that, at temperatures near the ‘ceiling temperature’, the copolymerization of sulphur dioxide with either cis - or trans -2- butene is accompanied by the geometrical isomerization of the 2-butene. The results of some kinetic studies of this latter reaction, using a vapour-pressure technique, are reported. Over the range investigated (25 to 60°C inclusive) the rate of this isomerization reaction increases with temperature according to the normal Arrhenius law, the overall energies of activation using benzoyl peroxide as the initiator being 16·5 ± 0·6 kcal mole –1 for the cis to trans isomerization and 18∙3 ± 0∙4 kcal mole –1 for the trans to cis isomerization. Prolonged reaction leads to the attainment of cis-trans equilibrium, and the value of the relevant thermodynamic functions are cis -2-butene→ trans -2-butene; in liquid sulphur dioxide, x B = 0∙09; ∆ H = – 1∙43 ± 0∙25 kcal mole –1 , ∆ S = – 2∙8 ± 0∙8 cal deg –1 mole –1 . These values differ from the values for an ideal liquid mixture of the cis - and trans -2-butenes. At 100°C and at high catalyst concentrations an additional isomerization reaction is detect­able; namely, that of formation of 1-butene by double-bond migration. The geometrical isomerization data are entirely consistent with the conclusion that the polymers formed from cis - and trans -2-butene are stereoisomeric (see also part III) and that one form of addition in the propagation step has a slightly lower energy of activation than the other.

Simplified Analysis for the Association of a Constrained Receptor to an Oscillating Ligand

2016 ◽  
Vol 83 (9) ◽  
Author(s):  
Xiaofeng Chen ◽  
Bin Chen
Keyword(s):  
Passage Time ◽  
Cyclic Loads ◽  
Single Bond ◽  
Physiological Conditions ◽  
Cell Matrix ◽  
The Mean ◽  
Simplified Analysis ◽  
The Stability ◽  
Cell Matrix Adhesion ◽  
Kinetics Of

The stability of a bond cluster upon oscillated loads under physiological conditions is strongly regulated by the kinetics of association and dissociation of a single bond, which can play critical roles in cell–matrix adhesion, cell–cell adhesion, etc. Here, we obtain a simplified analysis for the bond association process of a constrained receptor to an oscillating ligand due to its diffusion-independence, which can facilitate the potential multiscale studies in the future. Based on the analysis, our results indicate that the mean passage time for bond association intriguingly saturates at high oscillating frequencies, and there can also surprisingly exist optimal bond elasticity for bond association. This work can bring important insights into understanding of the behaviors of bond cluster under cyclic loads at the level of a single bond.

Direct observations of radiation-enhanced transformations in glass

1983 ◽  
Vol 41 ◽  
pp. 354-355
Author(s):  
J. F. DeNatale ◽  
D. G. Howitt
Keyword(s):  
Glass Matrix ◽  
Diffusion Mechanism ◽  
Bubble Formation ◽  
Silicate Glasses ◽  
Phase Decomposition ◽  
Direct Observations ◽  
Thin Foils ◽  
Oxygen Bubble ◽  
Electron Energy Loss ◽  
Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

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