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631.
632.
Hideharu Mori Mikio Yamahiro Kunihiko Tashino Kouki Ohnishi Koh-hei Nitta Minoru Terano 《Macromolecular rapid communications》1995,16(4):247-252
The short-period polymerization method was successfully applied to the synthesis of a novel diblock copolymer, polypropene-block-poly(ethylene-co-propene). The polymerization was carried out for ca. 0,1 s with a MgCl2-supported Ziegler catalyst. The copolymers obtained showed unimodal curves in gel-permeation chromatography without any peak in the low-molecular-weight region. After extraction with heptane, the fraction of poly(ethylene-co-propene) remained unchanged in the copolymer but disappeared in a commercial so-called block-type copolymer. All the results the formation of polypropene-block-poly(ethylene-co-propene), in which poly(ethylene-co-propene) is chemically linked with polypropene. 相似文献
633.
Hideharu Mori Kunihiko Tashino Minoru Terano 《Macromolecular rapid communications》1995,16(9):651-657
The chain transfer reaction by hydrogen in the initial stage of propene polymerization with MgCl2-supported Ziegler catalyst was studied by means of the stopped-flow polymerization. The yield and molecular weight of polypropene produced in the initial stage were not affected by hydrogen. Thus, the method was successfully applied to find the region in which hydrogen does not act as a chain transfer reagent. On the other hand, a chain transfer reaction proceeded in the initial stage of polymerization by using Zn(C2H5)2. Furthermore, when the catalyst was treated with Al(C2H5)3 before polymerization, the molecular weight of the produced polymer was decreased by using hydrogen, indicating that it acted as a chain transfer agent for the catalyst modified by pre-treatment. 相似文献
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Lukas Scheibelberger Toda Stankovic Kaja Liepert Andreas Kienzle Eva-Maria Patronas Dr. Theresa Balber Prof. Dr. Markus Mitterhauser Prof. Dr. Arvand Haschemi Dr. Katharina Pallitsch 《European journal of organic chemistry》2023,26(31):e202300339
Fluorinated carbohydrates are valuable tools for enzymological studies due to their increased metabolic stability compared to their non-fluorinated analogues. Replacing different hydroxyl groups within the same monosaccharide by fluorine allows to influence a wide range of sugar–receptor interactions and enzymatic transformations. In the past, this principle was frequently used to study the metabolism of highly abundant carbohydrates, while the metabolic fate of rare sugars is still poorly studied. Rare sugars, however, are key intermediates of many metabolic routes, such as the pentose phosphate pathway (PPP). Here we present the design and purely chemical synthesis of a set of three deoxyfluorinated analogues of the rare sugars d -xylulose and d -ribulose: 1-deoxy-1-fluoro-d -ribulose ( 1DFRu ), 3-deoxy-3-fluoro-d -ribulose ( 3DFRu ) and 3-deoxy-3-fluoro-d -xylulose ( 3DFXu ). Together with a designed set of potential late-stage radio-fluorination precursors, they have the potential to become useful tools for studies on the complex equilibria of the non-oxidative PPP. 相似文献
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