Attempted copolymerization of 1.3‐dioxolane with tetrahydrofuran by triethyl oxonium tetrafluoroborate

Abstract

Copolymerization of 1,3-dioxolane (DOL) with tetrahydrofuran (THF) was attempted with triethyl oxonium tetrafluoroborat+ (Et30BF4) as initiator. The gas chromatographic determination of the unreacted monomers during the reaction indicated that preferential polymerization of THF occurred in the initial stage of the reaction, and that once DOL began to polymerize after an induction period, the polymerization of T H F declined gradually and ceased. However, it was resumed, although very slowly, after the polymerization of DOL reached the equilibrium conversion. Two-step polymerizations of THF and DOL by utilizing the living nature of the polymerization by Et30BF4 yielded a mixture of the homopolymers. The mechanism of this unusual polymerization is discussed. The addition of THF t o the cationic chain ends with DOL as the terminal unit does not occur but proton transfer takes place. ZUSAMMENFASSUNG:Die Copolymerisation von 1.3-Dioxolan (DOL) mit Tetrahydrofuran (THF) wurde mit Triathyloxoniumtetrafluoroborat ((CzH&OBF4) als Initiator versucht. Es ergab sich aus der gaschromatographischen Bestimmung der Monomerkonzentrationen im Verlauf der Reaktion, dafi das THF vorzugsweise im Anfangsstadium der Reaktion polymerisiert und dafi die Polymerisation des T H F stufenweise abnimmt und schliefilich aufhort, sobald das DOL nach einer Induktionsperiode einmal begonnen hat zu polymerisieren. Jedoch beginnt die Polymerisation des THFwenn auch sehr langsamvon neuem, nachdem die Polymerisation des DOL das Gleichgewicht erreicht hat. Zweistufenpolymerisationen von THF und DOL, die mit (CzH5)30BF4 als Jebende" Polymerisation durchgefuhrt wurden, ergaben ein Gemiscb der Homopolymeren. Der Mechanismus dieser ungewohnlichen Polymerisation wird diskutiert : die Addition von THF an kationische Kettenenden niit endstandigem DOL-Baustein erfolgt nicht ; statt dessen tritt Hydridubertragung ein.

Cationic Copolymerization of 1,3-Dioxolane with Tetrahydrofuran Initiated with Methyl Fluorosulfate

“…3 studied the same copolymerization with Et 3 0SbCI 6 as an initiator and they concluded that the propagating species of DOL, which are supposedly solvated by THF monomers, grow only by the addition of DOL monomers, in agreement with the results of Yamashita et a/. 2 It seems strange at first glance that DOL cannot copolymerize with THF, because both DOL 4 · 5 and THF 6 • 7 copolymerize with 3,3-bischloromethyloxacyclobutane (BCMO), and both growing species of DOL and THF grow essentially by the SN2 mechanism, although the former has an oxycarbenium ionic character 8 -11 and the latter is a tertiary oxonium ionY One of the possible reasons for the reluctant cross-over propagations in the DOL-THF copolymerization system is the preferential occurrence of an oxonium ion exchange reaction at the growing chain end with DOL and THF units as the penultimate and terminal units, respectively. 2 Therefore, it would be expected that if the copolymerization is carried out under the conditions where propagations proceed through ester species, instead of ionic species, by using a superacid derivative as an initiator, a random copolymer might be formed from DOL and THF.…”

“…3 studied the same copolymerization with Et 3 0SbCI 6 as an initiator and they concluded that the propagating species of DOL, which are supposedly solvated by THF monomers, grow only by the addition of DOL monomers, in agreement with the results of Yamashita et a/. 2 It seems strange at first glance that DOL cannot copolymerize with THF, because both DOL 4 · 5 and THF 6 • 7 copolymerize with 3,3-bischloromethyloxacyclobutane (BCMO), and both growing species of DOL and THF grow essentially by the SN2 mechanism, although the former has an oxycarbenium ionic character 8 -11 and the latter is a tertiary oxonium ionY One of the possible reasons for the reluctant cross-over propagations in the DOL-THF 629 …”

“…2 • 3 Yamashita et a/. 2 confirmed by the gas chromatographic determination of the unreacted monomers during the copolymerization initiated with Et30BF4 that preferential polymerization of THF occurred in the initial stage of the copolymerization, and that once DOL began to polymerize after an induction period, the polymerization of THF slowed down gradually and eventually ceased. However, it was resumed, although very slowly, after the polymerization of DOL reached the equilibrium conversion.…”

“…2 It seems strange at first glance that DOL cannot copolymerize with THF, because both DOL 4 · 5 and THF 6 • 7 copolymerize with 3,3-bischloromethyloxacyclobutane (BCMO), and both growing species of DOL and THF grow essentially by the SN2 mechanism, although the former has an oxycarbenium ionic character 8 -11 and the latter is a tertiary oxonium ionY One of the possible reasons for the reluctant cross-over propagations in the DOL-THF copolymerization system is the preferential occurrence of an oxonium ion exchange reaction at the growing chain end with DOL and THF units as the penultimate and terminal units, respectively. 2 Therefore, it would be expected that if the copolymerization is carried out under the conditions where propagations proceed through ester species, instead of ionic species, by using a superacid derivative as an initiator, a random copolymer might be formed from DOL and THF. Conversely, if a random copolymer is actually obtained, it would be taken as a strong support for the presence of an ester species in the polymerization of DOL initiated with a superacid derivative.…”

Applications of magnetoelectrolysis

“…According to this study, the variation in the exchange current obtained by electrochemical methods is due to modifications of the structural state of the deposit. Chiba et al [34] and Yamashita et al [35] found that a magnetic field had no effect on the rate-determining step in copper deposition, but did increase the charge-transfer current and the efficiency of the deposition process. In contrast, the ratedetermining step of p-benzoquinone reduction in acetonitrile shifts from mass to electron transfer when a strong magnetic field is applied [36].…”