REMOVAL OR REDUCTION OF PERMANGANATE REDUCING COMPOUNDS AND ALKYL IODIDES FROM A CARBONYLATION PROCESS STREAM

DISCLOSED IS A METHOD TO MANUFACTURE HIGH PURITY ACETIC ACID. ALTHOUGH DESCRIBED IN RELATION TO THAT PRODUCED BY A LOW WATER CARBONYLATION PROCESS THE PRESENT INVENTION IS APPLICABLE TO OTHER MECHANISMS FOR PRODUCTION OF ACETIC ACID WHICH RESULTS IN FORMATION OF PERMANGANATE REDUCING COMPOUNDS SUCH AS ACETALDEHYDE AND ITS DERIVATIVES, AND ALKYL IODIDE IMPURITIES IN INTERMEDIATE PROCESS STREAMS.IT HAS BEEN FOUND THAT PERMANGANATE REDUCING COMPOUNDS AND ALKYL IODIDES MAY BE CONVENIENTLY REMOVED FROM A LIGHT PHASE OF AN INTERMEDIATE STREAM IN THE REACTION PROCESS BY EMPLOYING A MULTIPLE DISTILLATION PROCESS COUPLED WITH AN OPTIONAL POST EXTRACTION OF ACETALDEHYDE. THE DISTILLATION PROCESS INVOLVES FIRST DISTILLING A LIGHT PHASE TO CONCENTRATE THE PERMANGANATE REDUCING COMPOUNDS, AND IN PARTICULAR THE ACETALDEHYDE, AND THEN SEPARATING THE PERMANGANATE REDUCING COMPOUNDS AND ALKYL IODIDES IN A SECOND DISTILLATION TOWER. THE SECOND DISTILLATION SERVES TO REMOVE THE PERMANGANATE REDUCING COMPOUNDS AND ALKYL IODIDES FROM METHYL IODIDE, METHYL ACETATE, AND METHANOL MIXTURE. AS AN OPTIONAL THIRD STEP, THE TWICE DISTILLED STREAM MAY BE DIRECTED TO AN EXTRACTOR TO RECOVER ANY REMAINING QUANTITIES OF METHYL IODIDE FROM THE AQUEOUS ACETALDEHYDE WASTE STREAM. THIS PROCESS AFFORDS A FINAL PRODUCT IN GREATER THAN 99% PURITY. IT HAS BEEN FOUND THAT DURING SHUT DOWN OF THE INVENTIVE PROCESS, HIGHER MOLECULAR WEIGHT POLYMERS OF ACETALDEHYDE TEND TO FORM IN THE BASE OF THE SECOND DISTILLATION TOWER. TO AVOID OR MINIMIZE THE FORMATION OF THESE POLYMERS, A CONSTANT FLOW OF SOLVENT IS PASSED THROUGH THE BASE OF THE COLUMN.(FIGURE 1)