ArticleChemical science2022
Union carbide polymerization catalysts: from uncovering active site structures to designing molecularly-defined analogs.
Article in Chemical science, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
1 citing paper in PubMed.
- AssigningChemical science · 2023Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
8 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
The Union Carbide (UC) ethylene polymerization catalysts, based on chromocene dispersed on silica, show distinct features from the Phillips catalysts, but share the same heated debate regarding the structure of their active sites. Based on a combination of IR, EPR spectroscopies, labeling experiments, and DFT modeling, we identified monomeric surface-supported Cr(iii) hydrides, ([triple bond, length as m-dash]SiO)Cr(Cp)-H, as the active sites of the UC catalyst. These sites are formed in the presence of grafted and adsorbed chromocene as well as residual surface OH groups, only possible at high Cr loading, and involve a C-H activation of the Cp ring. These Cr-hydrides initiate polymerization, yielding Cr(iii) alkyl species that insert ethylene through a Cossee-Arlman-type mechanism, as evidenced by spectroscopic studies. These insights inspired the design of a well-defined analog, CpCr(CH(SiMe
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.