Structural studies of poly(1,2‐cyclohexene oxide) prepared with well‐defined organozinc compounds

Abstract

Three samples of poly(1,2-cyclohexene oxide) were prepared with ZnEb, (EtZnOMe),, and [[MeOCH,CH(Me)OZnO(Me)CHCH,OMe~ . (EtZnO(Me)CHC~OMe],] ([ Zn-MPh,,), respectively, as initiator. Each polymer sample was treated with butyllithium to form various decomposition products having double bonds or hydroxyl groups as end groups. Two dimeric diols, were obtained from the decomposition products and were found to have isotactic (SS-SS or RR-RR) and syndiotactic (RR-SS) structure, respectively. By comparison of the relative yield of the two dimeric diols from each sample with the relative intensity of the three major signals in their ' H NMR spectra, the latter were assigned to methine protons of isotactic, syndiotactic, and heterotactic triads (from downfield to upfield). It was found that most parts of the main chain of the polymer prepared with [Zn-MPh,, were composed of syndiotactic triads, SS-RR-SS (or RR-SS-RR), while the polymer prepared with ZnEG or (EtZnOMe), contained syndiotactic and heterotactic triads in comparable amounts.

Polymerization of cyclohexene oxide using yttrium isopropoxide and a bimetallic yttrium-aluminium isopropoxide as initiators

“…T g values were observed between 65 and 67 8 C as was found in the literature. 1 H and 13 C NMR spectra revealed an atactic structure similar to that decribed in the literature 8,9) .…”

“…Polymerization of cyclohexene oxide is generally very hard with classical initiators like CsOH, ZnEt 2 -H 2 O, or ZnEt 2 -ROH 4,8) which usually polymerize well other epoxides, e. g., propylene oxide. Some complex zinc initiators bearing methoxypropanol groups allowed to prepare poly(CHO) composed of syndiotactic and isotactic blocks 4,9) . Using a chiral initiator prepared from ZnEt 2 and (1R,2S)-ephedrin, stereoregular polymers were prepared containing simultaneously an optically inactive syndiotactic fraction and two optically active fractions of opposite configuration (RR and SS) 8) .…”

Stereoselective Ring‐Opening Polymerization of Heterocyclic Monomers

“…The activity differs significantly, depending on the alcohol used. Syndiotactic polymerization of cyclohexene oxide by the similar Zn catalyst was also reported (9,10). Al and Zn porphiryns (3,4) are effective initiators for living polymerization of propylene oxide (11).…”

“…The cobalt catalysts also promote isoselective polymerization of butene oxide and hexene oxide. Recently, Coates reported that dinuclear enantiopure cobalt complex (9) in combination with [Ph 3 P = N = PPh 3 ]OAc brings about enantioselective polymerization of various epoxides including propylene oxide (22,23). Enantioselectivity of the polymerization and isotacticity of the produced polymer are very high, for example the enantiomeric excess (e.e.)…”

Stereochemical behavior of oxirane and bioxirane in their polymerizations initiated with an organozinc complex having chair‐type structure

“…A previous study (Ref. 13) showed that [Zn-MP]2,2 complex was the unique initiator that caused a coordinate anionic polymerization of cyclohexene oxide (CHO) in a similar way to propylene oxide as shown in Table 1. Diethylzinc or ethylzinc alkoxide did induce the CHO polymerization which proceeded according to a cationic mechanism (Ref.…”