An apparatus for oxidation of a C 8 -C 12 alkylbenzene reactant to a C 8 -C 12 alkylbenzene hydroperoxide product, the apparatus comprising: a flow reactor comprising a reactant inlet, an oxidate product outlet, wherein the flow reactor is configured to provide a liquid flow from the reactant inlet to the oxidate product outlet, a gas inlet configured to introduce an oxygen-containing gas into the flow reactor, an inlet sparger configured to flow gas bubbles comprising the oxygen-containing gas within the liquid flow, preferably wherein the gas inlet is located to provide a flow of the gas bubbles to the flow reactor, more preferably wherein the gas bubbles are introduced into the flow reactor in a direction across a liquid flow direction and wherein the gas bubbles flow through the flow reactor in a direction coaxial with the liquid flow, and a reaction channel, wherein, in use, the liquid flow from the reactant inlet to the oxidate product outlet is through a reaction channel, preferably wherein the reaction channel has a diameter of greater than or equal to 6 mm, more preferably, wherein the reaction channel diameter is less than or equal to 100 mm, still more preferably, wherein the reaction channel diameter is 6 mm to 50 mm and wherein the inlet sparger has a single aperture configured to flow gas bubbles one at a time, serially, into the reaction channel, preferably wherein the inlet sparger comprises an array of sparger channels, wherein each sparger channel has a diameter of 0.01 to 0.9 mm, preferably wherein each sparger channel has a length of 2 mm to 100 mm, more preferably, wherein each sparger channel length is 5 mm to 25 mm. a flow reactor comprising a reactant inlet, an oxidate product outlet, wherein the flow reactor is configured to provide a liquid flow from the reactant inlet to the oxidate product outlet, a gas inlet configured to introduce an oxygen-containing gas into the flow reactor, an inlet sparger configured to flow gas bubbles comprising the oxygen-containing gas within the liquid flow, preferably wherein the gas inlet is located to provide a flow of the gas bubbles to the flow reactor, more preferably wherein the gas bubbles are introduced into the flow reactor in a direction across a liquid flow direction and wherein the gas bubbles flow through the flow reactor in a direction coaxial with the liquid flow, and a reaction channel, wherein, in use, the liquid flow from the reactant inlet to the oxidate product outlet is through a reaction channel, preferably wherein the reaction channel has a diameter of greater than or equal to 6 mm, more preferably, wherein the reaction channel diameter is less than or equal to 100 mm, still more preferably, wherein the reaction channel diameter is 6 mm to 50 mm and a reactant inlet, an oxidate product outlet, wherein the flow reactor is configured to provide a liquid flow from the reactant inlet to the oxidate product outlet, a gas inlet configured to introduce an oxygen-containing gas into the flow reactor, an inlet sparger configured to flow gas bubbles comprising the oxygen-containing gas within the liquid flow, preferably wherein the gas inlet is located to provide a flow of the gas bubbles to the flow reactor, more preferably wherein the gas bubbles are introduced into the flow reactor in a direction across a liquid flow direction and wherein the gas bubbles flow through the flow reactor in a direction coaxial with the liquid flow, and a reaction channel, wherein, in use, the liquid flow from the reactant inlet to the oxidate product outlet is through a reaction channel, preferably wherein the reaction channel has a diameter of greater than or equal to 6 mm, more preferably, wherein the reaction channel diameter is less than or equal to 100 mm, still more preferably, wherein the reaction channel diameter is 6 mm to 50 mm and wherein the inlet sparger has a single aperture configured to flow gas bubbles one at a time, serially, into the reaction channel, preferably wherein the inlet sparger comprises an array of sparger channels, wherein each sparger channel has a diameter of 0.01 to 0.9 mm, preferably wherein each sparger channel has a length of 2 mm to 100 mm, more preferably, wherein each sparger channel length is 5 mm to 25 mm.