摘要:
A process is described for the continuous preparation of dimethylvinylcarbinol (DMVC) by continuously reacting prenol with the aqueous solution of a protic acid in the still or in the lower part of a rectification column while distilling off the DMVC formed in the form of an azeotropic mixture with water, which comprises a) during the reaction ensuring that as far as possible no liquid two-phase mixture forms in the reaction mixture, b) distilling off the DMVC which forms at a reflux ratio of at least 2, as a result of which there is virtually no more prenol present in the distillate from the column, and c) setting the reaction volume and/or the amount of prenol added per hour and/or the concentration of protons in the reaction mixture in such a manner that the quotient, defined as residence time concentration coefficient, of the reaction volume and the volume of prenol added per hour multiplied by the concentration of protons in the reaction mixture has a value between 0.001 h·mol/l and 1 h·mol/l. In this connection, the formation of a liquid two-phase mixture in the reaction mixture is prevented, in addition to avoiding too large a prenol excess, by continuously taking from the reaction mixture a partial stream, passing it over a phase separation vessel, completely or at least largely removing there the small quantities, formed in the course of the reaction, of organic by-products which are insoluble or only partially soluble in water, and returning the aqueous phase to the reaction volume.