Sulfonation method

Claim 1

A PROCESS FOR THE PREPARATION OF A CONCENTRATE CONTAINING A METAL SULFONATE DISSOLVED IN A LUBRICATING OIL WHICH COMPRISES EXTRACTING A PETROLEUM LUBRICATING OIL FRACTION WITH A SELECTIVE SOLVENT SO AS TO REJECT THEREFROM SUBSTANTIALLY ALL MATERIAL HAVING A VGC LOWER THAN 0.80 AND SUBJECTING THE RESULTING EXTRACT TO A SECOND EXTRACTION WITH A SELECTIVE SOLVENT TO SEPARATE THEREFROM SUBSTANTIALLY ALL THE MATERIAL HAVING A BGC HIGHER THAN 0.92 AND LEAVE A LUBRICATING OIL STOCK WHICH HAS A VGC BETWEEN ABOUT .80 AND .92 AND IS SUBSTANTIALLY FREE OF MATERIALS HAVING VGC''S OUTSIDE OF THIS RANGE, AND HAS A VISCOSITY GREATER THAN ABOUT 200 SSU AT 130*F. AND IS SUBSTANTIALLY FREE OF MATERIALS HAVING LOWER VISCOSITIES; SULFONATING SAID STOK AT A TEMPERATURE BELOW ABOUT 170*F. EMPLOYING A SULFONATING AGENT SELECTED FROM A CLASS CONSISTING OF FUMING SULFURIC ACID AND SULFUR TRIOXIDE IN AN AMOUNT BETWEEN ABOUT 25 AND 150 PARTS OF SULFUR TRIOXIDE PER 100 PARTS OF STOCK; ADDING A VOLATILE HYDROCARBON DILUENT TO THE SULFONATION REACTION MIXTURE AND SEPARATING THE RESULTING SLUDGE FROM THE ACID OIL; NEUTRALIZING THE ACID OIL BY MEANS OF AN INORGANIC COMPOUND OF THE DESIRED METAL; AND SEPARATING A SULFONATE CONCENTRATE FROM THE NEUTRALIZED PRODUCT.