| 摘要 |
<p>1,217,234. 4,4 - Dimethyl - 1,3 - dioxane. FARBENFABRIKEN BAYER A.G. 16 Jan., 1968 [15 Feb., 1967], No. 2325/68. Heading C2C. A process for the preparation of 4,4-dimethyl- 1,3-dioxane from isobutene and aqueous formaldehyde in which the reaction is carried out in the liquid phase under superatmospheric pressure and at a temperature of 60‹ to 130‹ C. in the presence of sulphonic acid group containing cation exchangers based on cross-linked aromatic vinyl polymers comprises reacting the isobutene and aqueous formaldehyde together in a plurality of series connected, thoroughly stirred vessels, the molar ratio of isobutene to formaldehyde being in the range of from 0À5:1 to 3:1 and separating the reaction products in a separator situated between two successve vessels into a hydrocarbon layer and an aqueous layer including catalyst, in which the reactants are conducted through the series of reactors and the interposed separators and the hydrocarbon layer drawn off from the separators is separated by distillation into uncoverted hydrocarbons and into conversion products, and in which the hydrocarbons withdrawn from the separators are replaced by fresh or returned hydrocarbons, unreacted hydrocarbons driven off in the distillation being returned wholly or in part into the series of reactors.</p> |
