Cationic polymerization catalyzed by boron trifluoride‐ether complexes. Vinyl polymerization. LI.

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Abstract
The polymerizations of styrene and n‐butyl vinyl ether catalyzed by BF3 · ethyl ether or BF3 · tetrahydrofuran complexes were carried out dilatometrically in benzene at 30°C. In the case of BF3 · ethyl ether, the polymerization of styrene proceeded smoothly and the overall rate constant (k) was computed as 0.17 (mole/1.)−2/min., according to the equation of Rp = k[M]2[C]. BF3 · tetrahydrofuran, however, did not initiate the polymerization of styrene. Therefore, it was concluded that C2H5+‐cation from BF3·O(C2H5)2 initiated the polymerization of styrene, but BF3 · tetrahydrofuran did not produce any effective cation to initiate the polymerization.The polymerization of n‐butyl vinyl ether catalyzed by both complexes proceeded rapidly and the rates of polymerization were expressed as follows: where x is 4.75 for BF3·ethyl ether and 3.25 for BF3·tetrahydrofuran. It was assumed that BF3·tetrahydrofuran reacted with n‐butyl vinyl ether to give C4H9+‐cation which initiated the polymerization.