Untersuchungen in der Benztropylium-Reihe XII. Absorptionsspektrum und Acidität benzologer Tropylium-Kationen
作者:G. Naville、Hansruedi Strauss、E. Heilbronner
DOI:10.1002/hlca.19600430508
日期:——
The series of benzologue tropylium cations up to C15 has been completed by the preparation of 1,2; 3,4-dibenzo-tropylium cation (III), of (1′,2′-naphtha)-tropylium cation (V) and of (2′,3′-naphtha)-tropylium cation (IV). The absorption spectra and the relative acidities of these compounds are described.
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.