Complexing agent-modified trimetal cyanide catalyst

In a process for polymerizing an epoxide compound in the presence of a catalyst, the improvement wherein the catalyst is a metal hexacyanocobaltate cobalthexanitrite nitroferricyanide complexed with one or more organic complexing agents, said metal being any that forms a water-insoluble precipitate with hexacyanocobaltate cobalthexanitrite and nitroferricyanide groups, said complexing agent being selected from the group consisting of alcohols, aldehydes, ketones, ethers, amides, nitrites, sulfides and compounds having an S═O group, and wherein (a) the molar ratio of hexacyanocobaltate to cobalthexanitrite groups is about 1:0.1-1.0, (b) the molar ratio of hexacyanocobaltate to nitroferricyanide groups is from about 1:0.1-1.0 and (c) the molar ratio of hexacyanocobaltate groups to cobalthexanitrite and nitroferricyanide groups combined is about 1:0.5-1.5.

A method of making an active polymerization catalyst, comprising

• (a) forming a first solution of water soluble hexacyanocobaltate, cobalthexanitrite and nitroferricyanide compounds, said hexacyanocobaltate, cobalthexanitrite and nitroferricyanide compounds being present in proportions such that said solution contains a molar ratio of hexacyanocobaltate to cobalthexanitrite ions of about 1:0.1-1, a molar ratio of hexacyanocobaltate to nitroferricyanide ions of about 1:0.1-1.0, and a molar ratio of hexacyanocobaltate groups to cobalthexanitrite and nitroferricyanide groups combined of about 1:0.5-1.5,
• (b) mixing said first solution with a second solution of a water soluble salt of a metal that forms a water-insoluble insoluble precipitate with hexacyanocobaltate cobalthexanitrite and nitroferricyanide groups so as to precipitate a metal hexacyanocobaltate cobalthexanitrite nitroferricyanide, and
• (c) either simultaneously or after step (b), contacting said metal hexacyanocobaltate cobalthexanitrite nitroferricyanide with an organic complexing agent selected from the group consisting of alcohols, aldehydes, ketones, ethers, amides, nitriles, sulfides and compounds having an S═O group and, if no stoichiometric excess of metal salt is used in step (b), an additional quantity of a metal salt.