Propagation of Polydiene Salts in Ethereal Solvents

The very low value of EG seems to indicate the presence of two isomers, the less reactive form being more abundant at higher temperatures. Indirect evidence for this suggestion is given in Ref. 344. 

Discussion of the effects caused by kryptates, a most powerful solvating agent, is given on p. 156. 

Studies of propagation of polydiene salts in ethereal solvents are hampered by their instability and by a variety of isomerization processes altering the structure of their active centers. These side reactions vitiated the early investigations of those systems and made the reports published prior to 1965 of little value. Stability of ethereal solutions of the diene salts is greatly improved when they are kept at low temperatures, especially in the presence of salts suppressing the dissociation of living polymers398.  

In most systems, including living polystyrene, the free ions react faster with ethereal solvents than their ion-pairs 

6-10 2 M 1/2s 1, both at 30 °C. The kinetic work was supplemented by a conductance study yielding Kdiss = 5 10 9 M. This value might be too high because some conducting products could be formed by the side reactions. If accepted, it leads to = 3 104 M 1s 1. The remarkably low Kdiss, about 300 times smaller than that of lithium polystyrene, implies a very tight structure of lithium polyisoprenyl in that solvent. 

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