COOPER IS RECOVERD FROM ORES, OR SLAGS, OR TAILING PILES, IN WHICH THE CUPIFEROUS MATERIAL IS FINALLY SUBDIVIDED BY LEACHING WITH A DILUTE AQUEOUS ACIDIC LEACH SOLUTION, THE LEACH SOLUTION SEPARATED FROM INSOLUBLES, AND THE COPPER EXTRACTED USING AS EXTRACTANT AN ALKYL-3-METHYLQUINALDINIC ACID, THE ALKYL GROUP BEING FROM 6 TO 25 CARBONS ATOMS, SUCH AS 6-DODECYL-3-METHYLQUINALDINIC ACID, IN AN ORGANIC SOLVENT SYSTEM, SUCH AS 75/25 KEROSENE/ AROMATIC PETROLEUM FRACTION AND WHICH MAY CONTAIN UP TO 25% OF A C9 TO C14 ALKANOL, THE ORGANIC EXTRACTANT IN SOLUTION SEPARATED FROM THE AQUEOUS LEACH SOLUTION, AND THE COPPER STRIPPED FROM THE ORGANIC EXTRACTANT BY STRONG SULFURIC ACID, THE COPPER BEING STRIPPED AS COPPER SULFATE IN ACID SOLUTION, FROM WHICH COPPER IS RECOVERED AS ELECTROLYTIC GRADE COPPER BY ELECTROLYSIS. NEW QUINALDINIC ACIDS AND METHODS OF SYNTHESIS ARE DISCLOSED.