Cis-trans isomerization and13C-NMR chemical shift of polyphenylacetylene

Ishii, Fumiyuki; Matsunami, Shigeyuki; Shibata, Minako; Kakuchi, Toyoji

doi:10.1002/(sici)1099-0488(19990715)37:14<1657::aid-polb10>3.0.co;2-n

Cited by 8 publications

(11 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, an autoxidative process was used to explain the observed molecular weight decrease. A decrease in the molecular weight without a decrease in the cis content contradicts both our results at room temperature1–7, 23 and results at higher temperatures from our laboratory and other laboratories 29–33. In addition, a brief inspection of the 1 H NMR spectra from Figure 4 of ref.…”

Section: Introductioncontrasting

confidence: 61%

“…4(b,c)]. Treatment of PPA in bulk at 180 °C for 1 h under an inert atmosphere was repeatedly used for the thermal cis–trans isomerization of PPA 32, 33. Therefore the so‐called trans ‐PPA investigated previously32, 33 contains, in fact, a more complicated structure 3, 7–9…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, no information on the potential change in temperature during the compression at 20 °C was reported. In addition, some of these authors24, 25, 28, 30–39 did not seem to be aware of our previous thermally induced isomerization/cyclization/cleavage experiments. 1–7, 23…”

Section: Introductionmentioning

confidence: 97%

“…Both experiments produced 1,3,5‐triphenylbenzene as the molecular weight decreased as a result of intramolecular cyclization followed by chain cleavage. Furthermore, Ishii and coworkers32, 33 observed the formation of 1,3,5‐triphenylbenzene accompanied by chain cleavage and cis–trans isomerization at 150–180 °C under N 2 . A series of experiments from Tabata's laboratory34–39 showed the pressure‐induced cis–trans isomerization of cis ‐PPA derivatives at room temperature.…”

Section: Introductionmentioning

confidence: 98%

See 3 more Smart Citations

Dramatic decrease of the cis content and molecular weight of cis‐transoidal polyphenylacetylene at 23 °C in solutions prepared in air

Percéc

Rudick

Nombel

et al. 2002

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

The thermal cis-trans isomerization of cis-transoidal polyphenylacetylene (PPA) synthesized with Noyori's catalyst [Rh(C'CPh)(norbornadiene)(PPh 3 ) 2 ] has been investigated under both ambient and inert atmospheres in solution and in bulk. In all cases, an intramolecular cyclization results in cis-trans isomerization, and subsequent chain cleavage produces 1,3,5-triphenylbenzene. This reaction is accelerated by the presence of air, particularly when the reaction takes place in solution. Decreases in the cis content and molecular weight show that the intramolecular cyclization process takes place at 23°C in solution. The mechanism of this reaction is identical to that reported previously for cis-cisoidal and cis-transoidal PPA synthesized with Ziegler-Natta catalysts.

show abstract

Section: Introductioncontrasting

confidence: 61%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

Dramatic decrease of the cis content and molecular weight of cis‐transoidal polyphenylacetylene at 23 °C in solutions prepared in air

Percéc

Rudick

Nombel

et al. 2002

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

show abstract

“…Reportedly, main‐chain scission of the polymer could happen at a temperature as low as 20°C 13. Upon electron‐beam irradiation, cis ‐polyacetylene films showed improved stability according to a report by Roshchupkina et al8 For cis ‐polyacetylenes, cis–trans isomerization readily occurred when the polymers were subjected to γ‐ray irradiation14 or pressure;15 Ishii et al16 particularly explored the characterization of cis–trans isomerization by measuring 13 C‐NMR chemical shifts.…”

Section: Introductionmentioning

confidence: 99%

Stability of poly(N‐propargylamide)s under ultraviolet irradiation

Deng

Wang

et al. 2007

J of Applied Polymer Sci

View full text Add to dashboard Cite

This article investigates the photostability of poly(N-propargylamide)s under different conditions, on the basis of which application research for this class of highly functional polymers can be performed. With helical polymer 1 [monomer: CBCCH 2 NHCOCH(C 2 H 5 ) 2 ] taken as a representative, some affecting factors, including the ultraviolet (UV)-light intensity, presence of oxygen, far-UV and near-UV light, and temperature, were investigated. It was found that increasing the UV-light intensity accelerated the degradation of polymer 1. When oxygen was present, it also facilitated the degradation. Far-UV light rather than near-UV light played a predominant role in initiating the degradation of polymer main chains. Elevating the temperature of the polymer solution during UV irradiation made the degradation accelerate. Storing the polymer under weak UV light, in the absence of oxygen, and at a low temperature was favorable for keeping the polymer stable. These findings are important not only from a scientific point of view but especially for developing practical applications of this type of polymer on the basis of its photodegradability.

show abstract