| 摘要 |
1,3,5-Trioxane is prepared from highly concentrated aqueous formaldehyde solutions by continuously heating an aqueous solution containing about 30-70% by weight formaldehyde or paraformaldehyde and about 0.05 to 2 mole per cent (referred to the solution as a whole) of an acid, removing a mixture of trioxane, formaldehyde and water at the top portion of a fractionating stage, condensing said mixture, extracting the trioxane from said mixture in an extraction stage at an elevated temperature not exceeding 92 DEG C. with the aid of a water-immiscible solvent boiling at a high temperature with respect to the boiling point of trioxane (113 DEG C.), separating the resulting phases, returning the aqueous formaldehyde phase to said fractionating stage, and fractionating the trioxane-solvent phase to give pure trioxane. Specified solvents are chlorinated hydrocarbons, for example, a -chloronaphthalene and trichlorobenzene. Examples are given. A comparative example illustrates a process in which the condensed distillate is extracted with methylene chloride, the organic phase is separated, shaken with ammonia and dried over calcium chloride, and trioxane is crystallized from the resultant solution. |
