| 摘要 |
Manganous acetylacetonate, and the dihydrate thereof, are used as polymerization catalysts, specifically for the reaction between terephthalic acid and ethylene glycol. The catalyst produces a polymer which is white, and which does not darken on exposure to light. Example IV gives details of the polymerization. U.S.A. Specification 2,857,363 is referred to.ALSO:Manganous acetylacetonate is prepared by mixing an aqueous solution of a water soluble manganous salt and acetylacetone, and then titrating the mixture with an alkali metal hydroxide or ammonium hydroxide to a pH in the range 6 to 8, when the manganous acetylacetonate dihydrate is precipitated. The manganous compound, and the acetylacetone, are preferably dissolved in the minimum amount of water and, when mixed, titrated to a pH of 6-8 with a dilute solution of the specified hydroxide. The precipitate is dried and may be dehydrated by heating in a vacuum, subliming in a vacuum or by placing in a desiccator. The product is stable to air and may be used as a polymerization catalyst. Water soluble manganous salts mentioned are the chloride, bromide, iodide, formate, acetate, butyrate, succinate, sulphate, ammonium sulphate, nitrate, cyanide and thiocyanate. Examples are given and in a comparative experiment the manganous salt is added to a mixture of the hydroxide and acetylacetone in aqueous solution. U.S.A. Specification 2,857,363 is referred to. |
