Abstract: A reflection column which contains liquid distributors having at least 500 drip points/m2, which are arranged at an angle of about 90° C. to cloth layers of packing elements located immediately therebelow; and a combination of insulation and protective heating. The column is advantageously used for the rectification of mixtures of high-boiling air- or temperature-sensitive substances requiring effective separation efficiency.

Abstract: Unsaturated ketones of the formulae Ia and Ib are prepared by a process consisting of the combination of the following reactions: a) The conventional reaction of an allyl alcohol of the formula IIa or a propargyl alcohol of the formula IIb with an isopropenyl ether of the formula III with formation of a ketal of the formula IV as a byproduct, b) preparation of the isopropenyl ether of the formula III by reacting a ketal of the formula IV with propyne or allene, or a mixture thereof in the gas phase at elevated temperatures in the presence of a heterogeneous catalyst containing zinc or cadmium together with silicon or oxygen, and c) feeding the ketal of the formula IV formed in the reaction (a) into stage (b) for the preparation of the isopropenyl ether of the formula III again.

Abstract: Process for isolating pure substances from of mixtures of high-boiling air- and/or temperature-sensitive substances which require a high separation efficiency, by rectification under medium vacuum in columns containing metal cloth packings with ordered structure using channel liquid distributors with 500 or more drip points/m.sup.2, which are arranged at an angle of 90.degree. to the cloth layers of the packing elements located immediately below the distributors, in which two or more of the packing elements underneath the liquid distributors have only a very small height, which ensure virtual exclusion of air and are designed so that no heat exchange through the column wall can take place during the rectification. The patent also relates to packed columns which can be used for this process and to the use of this process and these columns for the final purification of vitamin E acetate by distillation.

Abstract: A process for preparing .alpha.-tocopherol or .alpha.-tocopheryl acetate by reacting 2,3,5-trimethylhydroquinone with isophytol or phytol in the presence of a zinc halide condensation catalyst and a proton donor in a solvent with or without subsequent esterification with acetic anhydride, which comprisesA. carrying out the reaction in a nonpolar solvent which is only slightly water-miscible, if at all andB. introducing the required zinc halide into the reaction in the form of a mixture of from 1 to 4 mol of water per mol of zinc halide.The possibility of introducing the zinc halide required in the process according to the invention in the form of a mixture of zinc halide and water which can be readily handled and metered at from 50 to 200.degree. C.

Abstract: A process for preparing 2,5,6-trimethyl-2-cyclohexen-1-one by reacting diethyl ketone with crotonaldehyde or a compound which is converted under the chosen reaction conditions into crotonaldehyde, in the presence of basic agents at elevated temperature, which comprisesa) simultaneously pumping one mole of crotonaldehyde or one mole of a compound which is converted under the reaction conditions into crotonaldehyde, about 5 to 30 moles of diethyl ketone and the aqueous solution or suspension of a strong base, through separate lines or at least partly in the form of a suitable mixture, continuously into a pressure vessel, which is heated where appropriate and which ensures vigorous mixing, in such a way thatb) the reaction temperature is between 150.degree. C. and 350.degree. C., and the average residence time in the pressure vessel is only about 0.1 second to 20 minutes.

Abstract: Packing elements with a low pressure drop for mass transfer column internals of the internal diameter of the column and of a height of from 40 to 300 mm made of dimensionally stable layers, which have an ordered structure and are in mutual contact, of cloth material or cloth-like material with a specific surface area of from 100 to 2000 m.sup.2 /m.sup.3, whereina) the shaped layers of cloth material or cloth-like material, preferably made of metal cloth, which are in mutual contact are arranged so that they form a multiplicity of narrow flow channels, preferably virtually triangular, virtually rectangular or else virtually equilateral hexagonal flow channels, in which the angle of inclination of the serration of the individual cloth layers of the packing to the column axis is only 0 to 25.degree., preferably 3 to 14.degree.