Propagation reaction 3-propiolactone

The kinetics of these polymerizations is complex. Both complexed ion pairs and free ions are involved in the propagation reactions and the free ion rate constants depend on monomer concentration. The relative reactivity of complexed ion pairs and free ions is temperature dependent. Above the inversion temperature of —35°C, free ions are more reactive than ion pairs, but below this temperature the ion pairs are more reactive. At 30 °C in DMF, the observed (average) propagation rate constant is 0.13 l/(mol s) [146], The anionic polymerization of a,a-dialkyl-P-propiolactones such as pivalolactone (a,a,-dimethyl-P-propiolactone) initiated with carboxylate anions exhibits the main characteristics of living polymerizations. 

A similar proton migration takes place in copolymerizations of acrylamide with cyclic imino ethers. The proton migration is part of the propagation process. Other examples are copolymerizations of a nucleophilic monomer, 2-phenyl-1,2,3-dioxaphospholane with electrophilic monomers. Here, too, the electrophilic monomers can be either acrylic acid or propiolactone. Identical products are obtained from both reactions ... 

Ring chain equilibria in the polymerization of < -valerolactone by lithium butoxide in THF have been found to be in accord with Jacobson-Stockmayer theory. The relative reactivities in the propagation of /ff-propiolactone are markedly temperature sensitive k /k+ varies from 5.6 at —20 C to 150 at 35 °C, the counterion being potassium complexed with dibenzo-18-crown-6 in dichloromethane. Roda and co-workers have continued their study of 2-pyrrolidone. The reactions of di-isopropenylbenzene (DIB) continue to be of interest. A paper by Beinert et al. in 1978 described the synthesis of a reagent, claimed to be an efficient difunctional initiator, by the reaction of one mole of /m-DIB with two of s-butyl-lithium. Protonation of the reagent solution with methanol generated butane and the hydrocarbon (5) was recovered. This species... 

These investigations are continuing to more fully verify the solvent effects observed, and in addition, similar studies are in progress on the effect of substituent size as well as reaction solvent on the anionic polymerization of a series of a-methyl-a-alkyl-6-propiolactones. An equivalent series of B-propiolactam monomers was recently investigated in this laboratory with the surprising result that the rates of propagation within this series increased with increasing size of the a-alkyl substituent (6). 

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