Abstract: The invention relates to a process for simultaneously performing two chemically successive reactions in a loop reactor, specifically reaction I) an optionally catalyzed equilibrium reaction between high-boiling liquid reactants, in which essentially one high boiler is formed as an intermediate and at least one low boiler as a by-product, and reaction II) a substantially diffusion-controlled reaction in which the liquid intermediate is reacted with at least one gaseous reactant to give the end product, wherein reactions (I) and (II), optionally after a start phase, are allowed to proceed simultaneously in the same apparatus, specifically loop reactor, and the loop reactor has a connectable gas-liquid circulation system coupled via an ejector mixing nozzle, in which circulated liquid phase is mixed in the ejector mixing nozzle with newly supplied gaseous reactant of reaction (II) (6) and/or gaseous reactant of reaction (II) aspirated by means of the ejector from the reactor via a connectable condenser (5), and

Abstract: The invention relates to a process for simultaneously performing two chemically successive reactions in a loop reactor, specifically reaction I) an optionally catalyzed equilibrium reaction between high-boiling liquid reactants, in which essentially one high boiler is formed as an intermediate and at least one low boiler as a by-product, and reaction II) a substantially diffusion-controlled reaction in which the liquid intermediate is reacted with at least one gaseous reactant to give the end product, wherein reactions (I) and (II), optionally after a start phase, are allowed to proceed simultaneously in the same apparatus, specifically loop reactor, and the loop reactor has a connectable gas-liquid circulation system coupled via an ejector mixing nozzle, in which circulated liquid phase is mixed in the ejector mixing nozzle with newly supplied gaseous reactant of reaction (II) (6) and/or gaseous reactant of reaction (II) aspirated by means of the ejector from the reactor via a connectable condenser (5), and

Abstract: A process for preparing phthalides of the general formula I, ##STR1## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independently hydrogen, C.sub.1-C.sub.4 -alkyl or C.sub.1 -C.sub.4 -alkoxy, by hydrogenating phthalic anhydrides of the general formula II, ##STR2## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each as defined above, with hydrogen in the presence of suspended catalysts of the Raney type in a hydrogenation apparatus by using a mixing apparatus to mix a liquid phase, which includes the catalyst and the phthalic anhydride used and resulting phthalide, and a gas phase, which includes the hydrogenating hydrogen, comprises using the mixing apparatus to introduce a mixing intensity of at least 50 W/l into the liquid phase.