Patent ID: 6140542
Filing Date: 2000-10-31
Classification: C07C

Abstract:
A process for the continuous preparation of ionones of the formulae I and II: ##STR3## in which R.sup.1 to R.sup.4 are H, --CH.sub.3 or --C.sub.2 H.sub.5, comprising cyclizing pseudoionones of the formula III, at a pseudoionone feed rate of at least 135 kg/hour, ##STR4## using concentrated sulfuric acid at temperatures from 20 to 90.degree. C. in the presence of organic solvents or diluents with cooling; terminating the reaction by hydrolysis of the reaction mixture with water, wherein both the cyclization of pseudoionones of the formula III and the subsequent hydrolysis of the reaction mixture are carried out in an essentially adiabatic reaction in one or more reaction mixing pumps which allow rapid mixing of the reactants, which are connected in series and each of which comprises a rotationally symmetrical mixing chamber formed from a peripheral wall and two end walls and of a mixing rotor made of material inert to sulfuric acid and with rotational drive,where the mixing chamber has in the peripheral wall at least one inlet opening for each component and one outlet opening for the reaction mixture, and annular channels in fluid connection to one another in the end walls, and wherein the heat of the two reactions is in each case partly or wholly removed with the aid of a downstream heat exchanger.