Preparation of ethylbenzene hydroperoxide

A process for the preparation of ethylbenzene hydroperoxide by the liquid-phase molecular oxygen oxidation of ethylbenzene in a reaction zone wherein liquid flows from an upstream portion to a downstream portion of said reaction zone which comprises the steps of introducing liquid ethylbenzene into the upstream portion of said reaction zone, introducing air into said reaction zone for direct contact of said molecular oxygen with said ethylbenzene in said zone, removing vapors comprising non-condensible inert gases from said reaction zone, cooling said vapors to separate condensible components from said vapors, recycling said cooled non-condensible gases to said reaction zone, and removing a liquid stream containing product ethylbenzene hydroperoxide from the downstream portion of said reaction zone, said zone being under a pressure of about 1 psig to about 1000 psig and said cooled recycling noncondensible gases being introduced into said zone at a rate to control the temperature of said zone within the range of about 100.degree. to about 165.degree. C., said temperature decreasing from the upstream portion of said zone to the downstream portion of said zone.