Abstract: A method and system for printing a three-dimensional porous structure (1). Interconnected filaments (2) are deposited in a predetermined arrangement in a plurality of stacked layers (11). The filaments (2) of the consecutive layers (11) are connected to one another to obtain the porous structure (1) with interconnected pores (15). The filaments are deposited in such a way that one or more preselected frangible regions (7) are formed in the arrangement of filaments (2). The one or more frangible regions (7) are connected to less-frangible regions (9) of the porous structure (1). The predetermined arrangement of interconnected filaments (2) is configured such that the one or more frangible regions (7) form structurally weakened zones of the porous structure (1) such that the porous structure (1) breaks along said one or more frangible regions (7) under influence of a load and/or a stress. The plurality of three- dimensional parts (10a) are releasable under influence of the load and/or stress.

Abstract: The present invention relates to a process for preparing monoacetylated hydroquinone compounds of the formula I, to the novel final products of the process and to a process for preparing the precursors.

Abstract: A process for preparing chromanol derivatives of the formula I ##STR1## where n is from 1 to 10,R.sup.1, R.sup.2,R.sup.3, R.sup.4 independently of one another are hydrogen or C.sub.1 -C.sub.4 alkyl,R.sup.5 is hydrogen, C.sub.1 -C.sub.4 alkyl, C.sub.6 -C.sub.10 aryl, C.sub.7 -C.sub.18 aralkyl, C.sub.7 -C.sub.18 alkylaryl, C.sub.1 -C.sub.22 acyl, or a group protecting the hydroxyl,by reduction of the corresponding 4-oxochromanol derivatives of the formula II ##STR2## comprises reacting the 4-oxochromanol derivatives of the formula II with metallic zinc in the presence of an acid or an acid mixture.Compounds of the formula I having C.sub.1 -C.sub.22 acyl as radical R.sup.5 can also be prepared by the above-described reduction of the compounds of the formula II with hydrogen as radical R.sup.5 and simultaneous or subsequent esterification.

Abstract: An improved process is described for preparing .gamma.,.delta.-unsaturated ke-tones, which are in demand as aroma substances and intermediates for vitamins and carotenoids, by reacting tertiary allyl alcohols and alkenyl alkyl ethers in the presence of acid catalysts at elevated temperature, which comprises carrying out the reaction in the presence of a phosphorus derivative of the formula IV ##STR1## where A and B are each a branched or unbranched alkyl or alkoxy having from 1 to 10 carbons, a substituted or unsubstituted aryl, cycloalkyl, aryloxy or cycloaryloxy;A can additionally be --H or --OH orA and B together are a substituted or unsubstituted tetramethylene or pentamethylene or substituted or unsubstituted phenyl-1,2-diol or 1,1'-binaphthyl-2,2'-diol.

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.