Direct formation of the helical polymer conformation in stereospecific polymer synthesis: x-ray crystallographic determination of linear chloral oligomers

Vogl, Otto; Xi, Fu; Vašš, František; Ute, Koichi; Nishimura, Tohru; Hatäda, Koichi

doi:10.1021/ma00202a051

Cited by 53 publications

(8 citation statements)

References 5 publications

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“…The CD spectral analyses revealed that the levorotatory as an effective initiator, giving optically active 171 with high optical rotations ([ α ] D over 4,000 ° ). Although the polymers 171 with high molecular weight are insoluble and their conformation cannot be directly elucidated, the helical structure of 171 has been verifi ed by NMR analyses [242,243] and crystallographic analyses of the corresponding oligomers [244] . [246] .…”

Section: Polymerization Of Aldehydesmentioning

confidence: 99%

Asymmetric Polymerization

Ito¹,

Nozaki²

2010

Catalytic Asymmetric Synthesis

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Section: Polymerization Of Aldehydesmentioning

confidence: 99%

Asymmetric Polymerization

Ito¹,

Nozaki²

2010

Catalytic Asymmetric Synthesis

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“…[45] Uniform chloral oligomers from dimer to nonamer were isolated by SEC from oligomer mixtures prepared with tC 4 H 9 OLi. [46][47][48][49][50][51][52][53][54][55] …”

Section: Uniform Polymers From Addition Polymerizationsmentioning

confidence: 99%

“…Uniform oligomers of chloral from dimer to nonamer were isolated by SEC from the oligomer mixtures, prepared with tC 4 H 9 OLi slightly below the ceiling temperature (Scheme 15), and studied by X-ray crystallographic analysis for single crystals and by NMR spectroscopy. [47][48][49][50][51][52][53][54][55] The dimer was found to be a mixture of meso and racemo isomers (3:1) but the trimer and the higher oligomers were completely isotactic. All the oligomers were found by single crystal X-ray analysis to assume rigid 4/1 helical conformations.…”

Section: Uniform Oligomers With Successive Dps For Understanding Reacmentioning

confidence: 99%

Synthetic Uniform Polymers and Their Use for Understanding Fundamental Problems in Polymer Chemistry

Hatäda

Kitayama

Ute

et al. 2004

Macromol. Rapid Commun.

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Summary: A uniform polymer is a polymer composed of molecules that are uniform with respect to molecular weight and constitution. Besides natural uniform polymers such as nucleic acids and polypeptide, synthetic uniform polymers have been obtained by a variety of approaches. In particular, a combination of living polymerization and supercritical fluid chromatography (SFC) separation is one of the promising ways for the preparation of uniform polymers. End‐functionalized uniform polymers enabled us to prepare uniform polymer architectures such as block, graft, comb, and star polymers. Their use for understanding the fundamental problems in polymer chemistry is discussed; topics include crystallization of polymers, chain conformation in solution, and association of stereoregular polymers in solution.

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“…The effect of the initiator structure of the first steps on the development of the stereochemistry of propagation were calculated, 66 and the structure and absolute configuration of the initiation 67 were determined by X-ray diffraction of the oligomers. 68,69 On-line gel permeation chromatography/mass spectrometry, the mixture of chloral oligomers was analyzed, and the assignment of meso/racemo addition products of the dimers was established. 70,71 At the temperature of initiation, above the T c of polymerization, the solution consists essentially of chloral monomer and the lithium salt of the addition product of tert-butoxide to one molecule of chloral, a racemate of the chloral-terminated alkoxide.…”

Section: Oligomerization Of Haloacetaldehydesmentioning

confidence: 99%