摘要:
The preparation of pyrocatechol monoethers or pyrocatechols of the formula Ia or Ib respectively ##STR1## ( R.sup.1 and R.sup.2 =H or C.sub.1 --C.sub.8 -hydrocarbon radicals; R.sup.3 =C.sub.1 --C.sub.8 -hydrocarbon radical ) by rearranging a 2-hydroxycyclohexanone dialkyl ketal II ##STR2## a) in the gas phase in the presence of a platinmetal or in the presence of a compound of one of these metals as catalyst in order to obtain a compound Ia, orb) carrying out step a) in the presence of water in order to obtain a compound Ib. The products are used as intermediates in the synthesis of pharmaceuticals, fragrances and flavors.
摘要:
A process for the preparation of phthalides of the formula I ##STR1## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently of one another, are hydrogen, C.sub.1 - to C.sub.4 -alkyl or C.sub.1 - to C.sub.4 -alkoxy, by reacting phthalic anhydrides of the formula II ##STR2## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are as defined as above, on hydrogenation catalysts at from 50.degree. to 400.degree. C. and at from 1 to 400 bar, wherein the hydrogenation catalysts employed are essentially free from Lewis acids.
摘要:
Fluorine content of tantalum and niobium hydroxides is reduced to under 0.5 weight % by washing such hydroxide precipitates (as obtained by HF digestion and solvent extraction) with dilute ammonia (1 to 10%) and then water in two washing stages. The first washing stage includes a partial neutralization and the used wash water of the second stage is advantageously recycled, after adjustment of its ammonia concentration, for use as the first stage washing liquid.
摘要:
A non-contacting seal between a rotating part to be sealed and a stationary part, in which the rotating part includes a coaxial disk which is surrounded by a stationary collecting channel axially closely adjoining the disk but without contacting it. The collecting channel forms a spirally shaped hollow space in the circumferential direction of the rotating part, with a sealing medium return line connected to the hollow space within the area of enlargement of the hollow space. A seal, however, may also be installed between the rotating part and the fixed part.
摘要:
An elastic loop 1 is provided for suspending an exhaust system of a motor vehicle at a vehicle floor of the motor vehicle. The elastic loop 1 has a basic body 4 made of an elastomeric material 5, the basic body 4 enclosing two receiving eyes 6 and 7, one of which being provided for receiving a supporting part, and the other of which being provided for receiving a part to be supported, and the basic body 4 comprising at least two elastic supporting bands 8 and 9 which run from the one receiving eye 6 to the other receiving eye 7 in a main plane of extension and operation of the loop. Further, the elastic loop 1 has a ring 21 enclosing the basic body 4 in the main plane, the ring 21 being a pre-cut piece 24 of a ribbon 20 which is continuously woven in consecutive one-layer and two-layer areas, i.e. once in a single closed layer and once in two separate layers, the pre-cut piece 24 including an entire two-layer area and at least parts of both adjacent one-layer areas.
摘要:
A process for preparing N-methyl-2-(3,4-dimethoxyphenyl)-ethylamine comprises hydrogenating 3,4-dimethoxyphenylacetonitrile with a methylamine of the general formula I ##STR1## where R.sup.1 is hydrogen, benzyl or tert-butyl, and hydrogen in the presence of a supported catalyst which comprises from 0.05 to 50% by weight of copper chromite, copper, silver, gold, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum or mixtures thereof, in the presence or absence of water at from 20.degree. to 200.degree. C. under from 1 to 300 bar.
摘要:
A process for the preparation of 4-hydroxymethyltetrahydropyrans of the formula I ##STR1## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are hydrogen, C.sub.1 - to C.sub.12 -alkyl, C.sub.3 - to C.sub.8 -cycloalkyl, aryl or C.sub.7 - to C.sub.20 -aralkyl, comprises reacting a tetrahydropyrancarboxylic ester of the formula II ##STR2## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are as defined above, and R.sup.5 is hydrogen or C.sub.1 - to C.sub.12 -alkyl, at from 50.degree. to 400.degree. C. and at from 1 to 400 bar in the presence of hydrogen and a hydrogenation catalyst.
摘要:
A method of manufacturing a tube bend of a metal comprises positioning a base ring in the range of the welding device, using the welding device to deposit a first section of metal on the ring, moving the ring and the welding device through an arc relatively to each other by substantially the thickness of the first section of metal and thereafter depositing a subsequent section over the first section and repeating the moving and the depositing until the desired section thickness is formed into a wall. The device includes means for mounting a plate for pivotal movement and a base ring mounted on the plate for movement therewith below a welding device arranged so that the welding device and the plate remove relatively through an arcuate path so that a series of sections of metal may be built up into a tube bend wall. The welding device advantageously includes an electrode feeder and the apparatus preferably includes a welding device to provide a plating along the side of the wall section which is built up.
摘要:
Catalysts consisting of from 85 to 100 wt % of copper oxide and zirconium oxide and from 15 to 0 wt % of metal oxides of the subgroups Ib to VIIb and VIII of the Periodic Table and a process for the preparation of amines from nitriles and nitrogen compounds selected from the group comprising ammonia and primary and secondary amines, at temperatures of from 80.degree. to 250.degree. C. and pressures of from 1 to 400 bar using hydrogen in the presence of said catalysts.
摘要:
A telescopic rod composed of a plurality of tubular rod sections which are mounted so as to be slidable within each other includes a multistage piston-cylinder unit which is arranged within the telescopic rod and is connected to the outermost rod section of the telescopic rod and to the last inner rod section of the telescopic rod. Locking bars are provided in the areas of the inner end faces of individual sections, wherein the locking bars are displaceable in a direction transversely of the longitudinal direction of the rod sections and wherein the locking bars can be placed in operative engagement with the respectively adjacent outer rod section. When the rod sections of the telescopic rod are in the extended end position, the locking bar of each inner rod section engages in a positively locking manner in an opening of the respectively outer adjacent rod section. Spring-biased clamps are provided on the outer sides of the rod sections located between the outermost rod section and the innermost rod section. When the telescopic rod is pushed together, the clamps grasp in a positively engaging manner bolts arranged at the end faces of the inwardly following rod sections.