Process for the manufacture of carboxymethyl cellulose involving 3-component, 2-phase liquid reaction medium

Claim 1

IN THE PROCESS OF PREPARING AN ALKALI METAL SALT OF CARBOXYMETHYLCELLULOSE WHEREIN CELLULOSE IS ETHERIFIED IN THE PRESENCE OF CAUSTIC ALKALI WITH A COMPOUND SELECTED FROM THE CLASS CONSISTING OFF MONOCHLOROACETIC ACID AND THE ALKALI METAL SALTS THEREOF, THE IMPROVEMENT WHICH COMPRISES CONTACTING SAID CELLULOSE WITH SAID CAUSTIC ALKALI IN A 3-COMPONENT, 2-PHASE LIQUID REACTION MEDIUM IN WHICH ONE LIQUID PHASE CONSISTS ESSENTIALLY OF MIXTURE OF WATER AND A WATER-MISCIBLE ALIPHATIC ALCOHOL HAVING FROM 2 TO 4 CARBON ATOMS, AND THE SECOND LIQUID PHASE CONSISTS ESSENTIALLY OF AN INERT WATER-IMMISCRIBLE ORGANIC LIQUID AND AN ADDITIONAL AMOUNT OF SAID WATER-MISCIBLE ALIPHATIC ALCOHOL, THE RATIO OF TOTAL LIQUID BY WEIGHT IN SAID REACTION MEDIUM TO DRY CELLULOSE BEING AT LEAST ABOUT 4:1 BUT NOT EXCEEDING ABOUT 20:1 THE RATIO OF WATER BY WEIGHT IN THE WATER-ALCOHOL PHASE TO DRY CELLULOSE AT THE BEGINNING OF THE REACTION BEING IN THE RANGE OF ABOUT 0.03:1 TO ABOUT 3.4:1, THE TOTAL AMOUNT OF SAID WATER-MISCIBLE ALIPHATIC ALCOHOL IN THE REACTION MEDIUM CONSTITUTING AT LEAST ABOUT 7% BY WEIGHT OF THE TOTAL WEIGHT OF THE LIQUID IN THE REACTION MIXTURE AT THE START OF THE REACTION, AND SUBSEQUENTLY EFFECTING EHTERIFICATION IN SAID 3-COMPONENT, 2-PHASE LIQUID REACTION MEDIUM.