Cumene: Benzene and Propylene over Solid Phosphoric Acid

Cumene (isopropylbenzene) is benzene with an isopropyl group, made by joining benzene and propylene. Ipatieff and Schaad of UOP (US 2,382,318, 1945) pass the two with plenty of benzene over 'solid phosphoric acid', a calcined paste of phosphoric acid and diatomaceous earth, at about 280 °C and 100 psi. The product needs no washing: it goes straight to distillation, and the spare benzene and propylene go round again. The picture: our diagram.