ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
In the presence of nucleophilic additives such as esters (ethyl benzoate, acetate, and chloroacetate), ethers (diethyl ether and 1,4-dioxane), and ammonium salts (nBu4NCl), oligomers of α-pinene with relatively high molecular weights (M̄n ≥ 1000) were obtained with the AlCl3/SbCl3 binary catalyst in toluene at 0°C ([AlCl3]0 = 42,5 mmol · L-1, Sb/Al = 0,50, [additive]0 = 10,6 mmol · L-1). The yield was 80-90 wt.-%, and the dimer content was as low as 6 wt.-%. Also in the polymerization at 25°C, the addition of ethyl benzoate increased the oligomer's average molecular weight (M̄n = 850) and decreased the dimer content (10 wt.-%), in contrast to the low M̄n (350) and the high dimer content (40 wt.-%) in the absence of the additive. The oligomers obtained in the presence of ethyl benzoate contained the repeating unit 1 which has an endo-olefin group, at higher ratio than in the absence of the additive. Phenomenologically, the role of the additives is to retard the polymerization so as to proceed at a moderate rate even at high temperature above 0°C and thereby to suppress the dimer formation.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1993.021941223
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