This process is a process for production of a vinyl chloride polymer by suspension polymerization or emulsion polymerization of vinyl chloride monomer or a mixture of vinyl chloride monomer with a vinyl monomer copolymerizable with said vinyl chloride monomer in an aqueous medium, characterized in that the polymerization is carried out in a polymerizer, the inner wall surface and portions of the auxiliary equipment thereof which may come into contact with the monomer during polymerization being previously coated with a scaling preventive comprising at least one selected from dyes, pigments and aromatic or heterocyclic compounds having at least 5 conjugated π bonds, while controlling the chloride ion concentration in the reaction mixture to not higher than 100 ppm. According to said process, scaling onto the inner wall surface of a polymerizer, etc. during polymerization can be prevented effectively and surely.
Ostermayer; Henrichsen, Chemische Berichte, 1884, vol. 17, p. 2445
作者:Ostermayer、Henrichsen
DOI:——
日期:——
Substrate‐Rhodium Cooperativity in Photoinduced
<i>ortho</i>
‐Alkynylation of Arenes
作者:Argha Saha、Animesh Ghosh、Srimanta Guin、Sanjib Panda、Dibya Kanti Mal、Abhirup Majumdar、Munetaka Akita、Debabrata Maiti
DOI:10.1002/anie.202210492
日期:2022.10.17
AbstractIn the realm of metallaphotocatalytic C−H activation strategy, the direct excitation of the transition metal which plays the dual role of light energy harnessing alongside performing the bond breaking and forming is a rare phenomenon. In this context we have developed the first photo‐induced Rh‐catalyzedortho‐alkynylation under ambient conditions without the requirement of silver salt, photocatalyst (PC) or any engineered substrate or catalyst. The transformation functions by the specific cooperative effect of a six‐membered rhodacycle which is the photo‐responsive species. The catalytic system allows the conjugation of arenes with sp3‐rich pharmacophoric fragments. The control experiments as well as the computational studies resolve the mechanistic intricacies for this transformation. An outer sphere electron transfer process from Rh to alkynyl radical is operative for the present photo‐induced transformation over the more common oxidative addition or 1,2‐migratory insertion pathways.