Preparation of complex diester synthetic lubricants

Claim 1

IN A PROCESS FOR PREPARING COMPLEX ESTERS FROM ONE MOLAR PROPORTION OF GLYCOL OF FROM 2-60 CARBON ATOMS PER MOLECULE, TWO MOLAR PROPORTIONS OF AN ALIPHATIC DICARABOXYLIC ACID OF 2-12 CARBON ATOMS PER MOLECULE AND 2 TO 3 MOLAR PROPORTIONS OF AN ALIPHATIC ALCOHOL OF FROM 4-20 CARBON ATOMS PER MOLECULE, THE IMPROVEMENT WHICH COMPRISES FIRST FORMING A CIRCULATING SYSTEM COMPRISING A REACTION ZONE AND A HEATING ZONE, ADDING TO THE CIRCULATING SYSTEM GLYCOL, A WATER ENTRAINER AND AN ESTERIFICATION CATALYST, THEN HEATING THE CIRCULATING MIXTURE TO REFLUX TEMPERATURE, THEN ADDING THE DICARBOXYLIC ACID AT A CONTROLLED RATE OF FROM 0.2 TO 1.0 MOLAR PROPORTION OF ACID/ HOUR TO THE SYSTEM, REMOVING WATER FROM THE SYSTEM UNTIL SUBSTANTIALLY ALL THE ACID HAS REACTED WITH THE GLYCOL, THEN ADDING SAID ALCOHOL AT A CONTROLLED RATE OF 0.25 TO 1.2 MOLAR PROPORTIONS OF ALCOHOL/HOUR, REMOVING WATER FROM THE SYSTEM AND RECOVERING SAID COMPLEX ESTER.