Processes and apparatuses for separating diisopropylbenzene (DIPB) and triisopropylbenzene (TIPB) from a feed including DIPB, TIPB, and polyalkylate heavies are disclosed. The disclosed processes include introducing the feed into a distillation column having a column top pressure of less than 5 psia, a column bottoms pressure of less than 3 psi, and preferably 2 psi or less above the column top pressure with a bottoms temperature ranging from about 435° F. to about 465° F. The processes also include taking off a side draw including at least 99.8 wt % of the DIPB and at least 50 wt % of the TIPB present in the feed and a bottoms stream including at least 95 wt % of the heavies contained in the distillation feed. The low temperature bottoms temperature enables high pressure steam to be used as the bottoms reboiler heat source.