Thin film evaporation of a crude amide feed in mixture with an alkali metal hydroxide

Claim 1

METHOD FOR THE PURIFICATION OF AN IMPURE FATTY ACID AMIDE CONTAINING FROM 14 TO 22 CARBON ATOMS AND CONTAINING FREE FATTY ACIDS AS IMPURITIES, COMPRISING THE STEPS OF: A. NEUTRALIZING SAID FREE FATTY ACIDS WITH AN ALKALI TO PRODUCE A NEUTRALIZED FATTY ACID AMIDE; B. SUBJECTING THE NEUTRALIZED AMIDE TO MOLECULAR DISTILLATION IN A WIPED-FILM EVAPORATOR BY MAINTAINING SAID AMIDE IN THE FORM OF A THIN FILM HAVING A THICKNESS LESS THAN ABOUT 1 MM. ON A DISTILLATION SURFACE HEATED AT OR ABOVE THE BOILING TEMPERATURE OF SAID AMIDE AT THE OPERATING PRESSURE OF SAID DISTILLATION, FOR A SHORT RESIDENCE TIME OF BETWEEN ABOUT 1 AND ABOUT 10 SECONDS, WHILE DISTILLING SAID AMIDE FROM SAID SURFACE AT A REDUCED PRESSURE BETWEEN ABOUT 0.005 AND ABOUT 5 MM. MERCURY, CONDENSING AND COLLECTING THE VAPORIZED AMIDE ON A CONDENSER, THE NEUTRALIZED FATTY ACID IMPURITIES NOT BEING DISTILLED; AND C. RECOVERING THE PURIFIED FATTY ACID AMIDE.