摘要:
Ruthenium tetroxide is obtained by oxidation of an alkali metal ruthenate in aqueous solution. The oxidizing agent used is ozone. The oxidation is carried out at a pH greater than or equal to 8.
摘要:
A process for the preparation of 3-hydroxytetrahydrofuran by catalytic dehydration of butane-1,2,4-triol, in which a catalyst chosen from the group of the bleaching earths is used and the dehydration is carried out in the presence of not less than 3 moles of water per mole of butane-1,2,4-triol.
摘要:
N-Alkylpiperidines or N-alkylpyrrolidines are obtained by hydrogenating a corresponding N-alkyldicarboxylic acid imide over a fixed catalyst by first working to only partial conversion, for example of about 50%, and distilling off the required product together with water from the partially converted mixture, where appropriate with recycling of the unconverted remainder.
摘要:
A process for the preparation of a hydrogenation catalyst which contains the oxides of the metals nickel, copper, molybdenum and aluminum and/or iron, and may or may not contain manganese oxide, by precipitating a solution of salts of the metals with an alkali metal carbonate at from 35.degree. to 95.degree. C. and a pH of from 5 to 9 and heating the precipitate at from 350.degree. to 700.degree. C., the amount of the metal salts being selected so that the catalyst contains from 5 to 70 percent by weight of aluminum oxide and/or iron oxide, the remainder being principally nickel oxide and, based on nickel oxide, from 20 to 40 percent by weight of copper oxide, from 0.5 to 6 percent by weight of molybdenum oxide and from 0 to 10 percent by weight of manganese oxide.
摘要:
The invention provides the means to enhance in E. coli-based expression systems the formation of fusion polypeptides containing as an N-terminal tag a biotinylation polypeptide. By way of specifically exchanging in the nucleic acid sequence encoding the biotinylation polypeptide nucleotides at 11 discrete positions enhances the formation of the total fusion polypeptide by at least 40%.
摘要:
A process for breaking down aromatics in industrial wastewaters that contain small amounts of aromatics by reaction with an ozone-containing oxygen stream at a temperature of from 40 to 70° C. and at a pH of from 4 to 7, involves treating industrial wastewaters that contain small amounts of aromatics in two stages with an oxygen stream that contains from 5 to 8% by volume of ozone with thorough mixing by causing the wastewater to flow upward through two reaction zones, the overflow of the wastewater at the top of the first reaction zone entering the second reaction zone at the base, the purified wastewater being obtained at the top of the second reaction zone, the ozone-containing oxygen stream first entering at the base of the second reaction zone, and the waste gas obtained at the top of the second reactor being introduced at the base of the first reaction zone, and, furthermore, a gas containing less than 0.2% by volume of ozone being obtained at the top of the first reaction zone.
摘要:
In a method of controlling the brake pressure of a vehicle brake system equipped with anti-lock protection it is provided to measure the slip and/or rotational retardation of a wheel whose brake is applied and to compare each measured value with a given threshold value so as to lower the brake pressure if the threshold value proves to have been surpassed. Undesired pressure reductions can be avoided by increasing the threshold value for given periods of time from a basic value (S.sub.G) and subsequently decreasing it again. At a point in time T.sub.1 at which the rotational retardation of the braked wheel is greater than a value corresponding to a physically feasible slowdown of the vehicle the threshold value is increased abruptly, to be decreased thereafter according to a predetermined function of time. During the lowering of the threshold value the change in speed of the retarded wheel is measured over given intervals of time .DELTA.T and compared with the instantaneous higher threshold value. If the comparison demonstrates that the change in speed in question is greater than the instantaneous raise in threshold value, the threshold value is reduced to the basic value (S.sub. G).
摘要:
Cyclic N,N'-dimethylureas are prepared by catalytic hydrogenation of a cyclic urea which carries hydroxyl groups in the .alpha.-position to the two nitrogen atoms.
摘要:
N-substituted cyclic amines of the general formula I ##STR1## where A is an alkylene group or a --(CH.sub.2).sub.n --[--O--(CH.sub.2).sub.m ].sub.r group which may be monosubstituted or polysubstituted by radicals R without the radicals R in a defined compound having to be identical, R is alkyl, alkoxyalkyl, unsubstituted or alkyl-substituted or alkoxy-substituted cycloalkyl, cycloalkylalkyl, aryl or arylalkyl, n and m independently of one another are each from 2 to 8 and r is from 1 to 3, the --(CH.sub.2).sub.n --[O--(CH.sub.2).sub.m ].sub.r group consisting of from 5 to 12 members, are prepared by reacting a primary amine of the general formula IIR--NH.sub.2 (II)with a diol of the general formula IIIHO--A--OH (III)where R and A have the abovementioned meanings, and hydrogen in the presence of a copper-containing hydrogenation/dehydrogenation catalyst at elevated temperatures and under superatmospheric pressure, by a process in which the reaction is carried out in the presence of a catalytic amount of a basic alkali metal compound or alkaline earth metal compound.
摘要:
An improved catalyst for the complete hydrogenation of acetylenically unsaturated alcohols and based on nickel, copper and manganese. The catalyst is used without a support and molybdenum is additionally included in an amount approximately equal to the content of manganese.