Cationic polymerization of cyclic dienes. X. Cationic polymerization of 1‐vinylcyclohexene and 3‐methyl‐1,3‐pentadiene

Abstract

Abstract1‐Vinylcyclohexene (VCH), which has one of the double bonds in the ring and the other outside the ring, was synthesized and polymerized by cationic catalysts. The reactivity of VCH was very large in the polymerizations catalyzed by boron trifluoride etherate (BF3OEt2) and stannic chloride–trichloroacetic acid complex. Similar to other cyclic dienes, the polymerization of VCH was a nonstationary reaction having a very fast initiation step. The polymerization proceeded by either a 1,2‐ or a 1,4‐propagation mode in which vinyl group was always involved. Particularly when BF3OEt2 was used as a catalyst, an intramolecular proton or an intramolecular hydride ion transfer reaction took place, resulting in the formation of methyl groups in the polymer. The degree of polymerization of polymer formed was about 10. This indicates the preponderance of monomer transfer reaction. To investigate the reason for the high reactivity of cyclic dienes, cationic copolymerizations of VCH and 3‐methyl‐cis/trans‐1,3‐pentadiene (cis/trans‐MPD) was carried out. The relative reactivity of monomers decreased in the order VCH > trans‐MPD > cis‐MPD. On the other hand, the resonance stabilization of monomers decreased in the order VCH > trans‐MPD > cis‐MPD. Therefore, it could be considered that the monomer reactivity is mainly determined by the stability of carbonium ion intermediate. The relative stability of carbonium ion must be VCH > trans‐MPD > cis‐MPD. Thus the influence of the conformation of ion on its stability was clearly demonstrated.

Shedding light on the poly(5‐ethylidene‐2‐norbornene) microstructural differences: Skeleton rearrangements during polymerization

“…This group can be pictured as a conjugated cis‐trans diene (Figure 2, region (II)), (Scheme 4). 31,32 Furthermore, the small absorption bands in the region sweeping 945 and 980 cm −1 (Figure 1, region (VI)) correspond to conjugated cis , trans diene 33 …”

“…This group can be pictured as a conjugated cis-trans diene (Figure 2, region (II)), (Scheme 4). 31,32 Furthermore, the small absorption bands in the region sweeping 945 and 980 cm À1 (Figure 1, region (VI)) correspond to conjugated cis, trans diene. 33 The absorption band located at 880-900 cm À1 (R 1 R 2 C CH 2 , vinylidene end groups) confirmed the occurrence of a chain termination reaction known as β-hydrogen elimination (Figure 1, region (V)).…”

Kombination von Styrol‐ und Dien‐Struktur zu einem zyklischen Dien: Anionische Polymerisation von 1‐Vinylcyclohexen (VCH)

“…Die erste Arbeit über die Polymerisation von 1‐Vinylcyclohexen (VCH) von Hara et al. erschien 1971 [2] . Die Autoren polymerisierten VCH unter Einsatz kationischer Initiatoren und berichteten sowohl über eine 3,4‐ als auch eine 1,4‐Propagationsweise.…”

Merging Styrene and Diene Structures to a Cyclic Diene: Anionic Polymerization of 1‐Vinylcyclohexene (VCH)

“…However, cyclic 1,3-dienes with one vinyl double bond have been explored only to a limited extent. The first report on the polymerization of 1vinylcyclohexene (VCH) was published in 1971 by Hara et al [2] They polymerized VCH by cationic initiators and reported both 3,4-and 1,4-propagation mode, albeit no SEC measurements were conducted. Bonnans-Plaisance investigated the polymerization of VCH by cationic or radical initiators.…”