Stereospecificity in the Polymerization of Acrylonitrile Using Anionic Initiators Including Dialkylmagnesium

Study on the Stereoregularity of Polyacrylonitrile Produced by Precipitation Polymerization in Supercritical CO2

“…So far, many studies on the stereoregularity of polyacrylonitrile (PAN) have been carried out by 13 C NMR. [10][11][12][13][14] It is generally believed that the CN carbon peak region roughly separates into three envelopes corresponding to I (isotactic), H (heterotactic), S (syndiotactic) triads and each envelope splits in a very small chemical shift range into 3 or 4 peaks due to pentad sequences. 12 Here, we want to evaluate the pentad tacticity of the CO 2 -PAN from the intensities of cyano peaks splitting into ten peaks in 13 C NMR spectra, and tried to examine these values by statistical models.…”

Polymerization of acrylonitrile catalyzed by thiolate complexes of divalent and trivalent lanthanoids

“…At this temperature, a side reaction such as the addition of a carbanion to the cyano group of a monomer thus terminating the propagation is negligible. 3 We used thiolate complexes of lanthanoid(III) complexes, tris(2,4,6-triisopropylbenzenethiolate) complexes of samarium(III) (1a) and ytterbium (1c), which exhibited very high activity in polymerization to give atactic polymers with unimodal molecular weight distribution and high molecular weight (M n % 70 000), the activity being comparable to that of anionic polymerization using alkyl, 2,3,19 arene, 5,6 amide 7 and alkoxide 8 compounds of alkali metals and alkaline earth metals (see Table 2). We have already reported that the polymerization of MMA was retarded by coordination of HMPA to lanthanoid(III), though the syndiospeci®city and the molecular weight distribution of PMMA were improved compared to those of the corresponding arenethiolate complexes bearing THF ligands.…”

Synthesis of highly isotactic poly(N,N‐diethylacrylamide) by anionic polymerization with grignard reagents and diethylzinc

“…They also found that diisotactic poly(t-butyl crotonate) was produced with t-BuMgBr under similar conditions. The stereospecific polymerization of acrylonitrile with dihexylmagnesium in the presence of di(isobutyl)aluminum in xylene was discovered by Kamide et al, 7 although the polymer yield was very low. Natta et al 8 prepared isotactic poly(2vinylpyridine) with diethylaminomagnesium halide or diphenylaminomagnesium halide in toluene, and they examined the crystallinity of the polymer produced by X-ray diffraction.…”