An apparatus for the continuous reaction of liquids with gases, in particular for the preparation of toluenediamine by hydrogenation of dinitrotoluene, which comprises - a vertically elongated reactor in which there is a reaction space, - at least one heat exchanger comprising heat exchanger tubes which are arranged within the reactor, - at least one inlet for introducing the cooling medium into the heat exchanger, - at least one outlet for taking the cooling medium off from the heat exchanger, - at least one inlet for introducing the gaseous reactant into the reaction space, - at least one inlet for introducing the liquid reactant into the reaction space, - at least one mixing chamber, - at least one downward-directed motive jet nozzle for introducing the reaction medium, which is arranged vertically in the gas space of the reactor and the outlet of which is arranged above the at least one mixing chamber and which forms a jet pump with the mixing chamber and is in fluid communication with the reaction space, - at least one outlet for taking the reaction medium off from the reactor, and - at least one means arranged below the heat exchanger and below the mixing chamber for diverting the reaction medium flowing downward through the mixing chamber in such a way that the reaction medium once again flows upward through the heat exchanger, and - wherein an external circuit with a pump arranged therein establishes a fluid connection between the outlet for the withdrawal of the reaction medium from the reactor and the at least one motive jet nozzle for the introduction of the reaction medium into the reactor, wherein - the heat exchanger tubes are hollow bodies provided with openings at the ends and are arranged in a bundle of tubes, wherein the number of tubes in the bundle of tubes is 100 to 10 000, and - the region surrounding the heat exchanger tubes is in fluid communication with the inlet for introducing the cooling medium and the outlet for taking off the cooling medium and - the inner region of the heat exchanger tubes forms part of the reaction space and is in fluid communication with the at least one motive jet nozzle and the outlet for taking off the reaction medium. - a vertically elongated reactor in which there is a reaction space, - at least one heat exchanger comprising heat exchanger tubes which are arranged within the reactor, - at least one inlet for introducing the cooling medium into the heat exchanger, - at least one outlet for taking the cooling medium off from the heat exchanger, - at least one inlet for introducing the gaseous reactant into the reaction space, - at least one inlet for introducing the liquid reactant into the reaction space, - at least one mixing chamber, - at least one downward-directed motive jet nozzle for introducing the reaction medium, which is arranged vertically in the gas space of the reactor and the outlet of which is arranged above the at least one mixing chamber and which forms a jet pump with the mixing chamber and is in fluid communication with the reaction space, - at least one outlet for taking the reaction medium off from the reactor, and - at least one means arranged below the heat exchanger and below the mixing chamber for diverting the reaction medium flowing downward through the mixing chamber in such a way that the reaction medium once again flows upward through the heat exchanger, and - wherein an external circuit with a pump arranged therein establishes a fluid connection between the outlet for the withdrawal of the reaction medium from the reactor and the at least one motive jet nozzle for the introduction of the reaction medium into the reactor, - the heat exchanger tubes are hollow bodies provided with openings at the ends and are arranged in a bundle of tubes, wherein the number of tubes in the bundle of tubes is 100 to 10 000, and - the region surrounding the heat exchanger tubes is in fluid communication with the inlet for introducing the cooling medium and the outlet for taking off the cooling medium and - the inner region of the heat exchanger tubes forms part of the reaction space and is in fluid communication with the at least one motive jet nozzle and the outlet for taking off the reaction medium.