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.
New gem-dihydroperoxides were successfully used for DBU-promoted enantioselective epoxidation of 2-substituted 1,4-naphtlloquinones. The corresponding 1,4-naphthoquinone epoxides were obtained in yields up to 97% and ee's up to 82%. (C) 2009 Elsevier Ltd. All rights reserved.
The Action of Diazomethane Derivatives and of Azides on Alpha and Beta Naphthoquinones
作者:Louis F. Fieser、Jonathan L. Hartwell
DOI:10.1021/ja01311a029
日期:1935.8
Moehlau; Klopfer, Chemische Berichte, 1899, vol. 32, p. 2148