METHOD FOR PREPARING TRIOXANE Russian patent published in 2004 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: method involves regeneration of heteropolyacid as a catalyst in process for preparing trioxane from the depleted reaction mass. Method involves preparing trioxane from formaldehyde aqueous solutions in catalysis with tungsten heteropolyacids, among them, with additions of inorganic salt. Process is carried out in combined regimen of chemical reaction and product isolation from reaction zone using fractionation and distillation. Then catalyst (heteropolyacids) is extracted from the spent reaction solution by extraction using organic extractants, such as butanol-1, butanol-2, pentanol-1, pentanol-2, cyclohexanol, octanol-1, decanol-1, 4-methyl-2-pentanone, butyl ester, benzene, nitrobenzene, ethyl acetate or their mixtures, by evaporation of prepared extract to the parent volume of reaction mass and conversion of heteropolyacid to an aqueous phase. Azeotropic process in extractant distillation off is carried out using water and extractive rectification of heteropolyacid an aqueous solution is carried out using formaldehyde (50-60% aqueous solution) as extractant. Solution containing heteropolyacid, water and formaldehyde is prepared in column still being this solution can be used for the further synthesis. Regenerated heteropolyacid retains its activity and can be used as a catalyst in trioxane synthesis repeatedly. EFFECT: improved preparing method, reduced consumptions in producing trioxane. 2 tbl, 1 ex