Abstract: A process for the production of 2,3,5-trimethylhydroquinone diesters by aromatization of 2,6,6-trimethyl-2-cyclohexene-1,4-dione (4-oxoisophorone, ketoisophorone, KIP) with an acylating agent and an acidic soluble or insoluble catalyst, which process may be operated alternatively continuously or discontinuously. The process includes the following steps: a) a carboxylic anhydride having a C1 to C4 alkyl residue is used as the acylating agent, b) after the reaction, a proportion of the resultant carboxylic acid is optionally removed by distillation, c) the reaction solution is cooled, d) the product which has crystallized out is separated and washed, and e) the filtrate is returned to step a).

Abstract: A method for epoxidation of olefins with 2 to 6 C atoms, especially propene, with hydrogen peroxide in the gas phase at a temperature below 250° C. The reaction is carried out by bringing a gas mixture containing the olefin, hydrogen peroxide and water into contact with the catalyst from the series of compounds of an element of the 4th to the 6th subgroup of the periodic table or of arsenic or selenium and molecular sieves in the absence of a liquid phase. Titanium-containing molecular sleeves are preferred catalysts.

Abstract: Granulates which contain titanium silicalite-1 are composed of silicon dioxide, titanium dioxide and titanium silicalite-1 crystals. The granulates can be prepared by spray-drying or spray granulating the crystallization suspension. The granulates may be used as suspension catalysts, such as for the epoxidation of olefins using hydrogen peroxide.