Abstract: Dodecene-1 and 1-tetradecene can be rectified from a mixture containing 1-dodecene and 1-tetradecene and triethylaluminum ("TEA") which has about the same normal boiling point as 1-dodecene and 1-tetradecene by feeding the above mixture to an intermediate point of a rectification column maintained under sufficient vacuum (e.g. 5-30 torr) such that the temperature at the intermediate feed point is about 250.degree.-260.degree. F. and the overhead distillation temperature is about 190.degree.-240.degree. F. The TEA which normally boils at about the same temperature as 1-dodecene and 1-tetradecene will exist as a dimer permitting part of the 1-dodecene and 1-tetradecene to distill overhead and most of the TEA to exit the bottom of the column.