Process for the manufacture of 1, 3, 5-trioxane

Claim 1

IN THE PROCESS FOR THE MANUFACTURE OF 1,3,5-TRIXANE WHEREIN AN AQUEOUS SOLUTION CONTAINING ABOUT 30 TO 70% BY WEIGHT OF AT LEAST ONE SUBSTANCE SELELCTED FROM THE GROUP CONSISTING OF FORMALDEHYDE AND PARAFORMALDEHYDE AND ABOUT 0.05 TO 2 MOL PERCENT OF AN ACID IS CONTINUOUSLY HEATED IN A FRACTIONATING STAGE, A MIXTURE OF TRIOXANE, FORMALDEHYDE AND WATER IS REMOVED AT THE TOP PORTION OF SAID FRACTIONATING STAGE AT A TEMPERATURE OF 89* TO 92* C. UNDER ATMOSPHERIC PRESSURE, THE TRIOXANE IS EXTRACTED FROM SAID MIXTURE IN AN EXTRACTION STAGE WITH THE AID OF A WATER-IMMISCIBLE SOLVENT, THE RESULTING PHASES COMPRISING A SOLUTION OF TRIOXANE IN THE WATER-IMMISCIBLE SOLVENT AND AN AQUEOUS FORMALDEHYDE SOLUTION ARE SEPARATED, THE AQUEOUS FORMALDEHYDE SOLUTION IS RETURNED INTO THE FRACTIONATING STAGE AND THE TRIOXANE DISSOLVED IN THE WATERIMMISCIBLE SOLVENT IS DISTILLED OFF, THE IMPROVEMENT WHICH COMPRISES EXTRACTING THE TRIOXANE IN THE EXTRACTING STAGE WITH A-CHLORONAPHTHALENE IS THE EXTRACTING AGENT AT A TEMPERATURE OF ABOUT 60 TO 70*C., RETURNING THE AQUEOUS FORMALDEHYDE SOLUTION AFTER SEPARATION OF THE RESULTING PHASES INTO ZONES OF EQUIVALENT FORMALDEHYDE CONCENTRATION IN THE FRACTIONATING STAGE, INTRODUCING THE SOLUTION COMPRISING TRIOXANE IN A-CHLORONAPHTHALENE APPROXIMATELY INTO THE CENTER PORTION OF A FIRST DISTILLING STAGE; WITHDRAWING AT THE TOP PORTION OF SAID FIRST DISTILLING STAGE WATER, FORMALDEHYDE AND A PORTION OF THE TRIOXANE; RETURNING SAID MIXTURE INTO THE EXTRACTION STAGE; INTRODUCING THE TRIOXANE AND THE A-CHLORONAPHTHALENE AS THE SUMP PRODUCT OF THE FIRST DISTILLING STAGE APPROXIMATELY INTO THE CENTER PORTION OF A SECOND DISTILLING STAGE; DISTILLING OFF PURE TRIOXANE AT THE TOP PORTION OF SAID SECOND DISTILLING STAGE; AND REPUMPING THE A-CHLORONAPHTHALENE AS THE SUMP PRODUCT OF THE SAID SECOND DISTILLING STAGE INTO THE EXTRACTING STAGE.