摘要:
The invention relates to a process for reducing the dimerization of piperidines of the formula I ##STR1## where R.sup.1 to R.sup.4 are C.sub.1 - to C.sub.6 -alkyl, R.sup.1 and R.sup.2 and/or R.sup.3 and R.sup.4 together are a CH.sub.2 chain having 2 to 5 carbon atoms, which comprises adding to the piperidine from 0.001 to 0.2% by weight of a reducing agent of the formula MXH.sub.4-m Y.sub.m, where M is an alkali metal, NR.sub.4, where R are identical or different C.sub.1 -C.sub.4 -alkyl groups, or an equivalent of an alkaline earth metal or an equivalent of zinc, X is boron or aluminum, Y is H or CN and m is 0 or 1. The invention also relates to a mixture of piperidines of the formula I, from 0.001 to 0.2% by weight of a reducing agent and from 1 to 1000 ppm of dimers of the piperidines of the formula I, and to the preparation of hindered amine light stabilizers therefrom.
摘要:
A process for purifying crude piperidines of the formula I ##STR1## where R.sup.1 to R.sup.4 are C.sub.1 -C.sub.6 -alkyl, or R.sup.1 and R.sup.2 and/or R.sup.3 and R.sup.4 together are a CH.sub.2 -chain of 2 to 5 carbons, which comprises, in a first step, removing high-boiling substances and, if present, water from the crude piperidines by distillation; in a second step, adding from 0.01 to 5% by weight, based on the product of the first step, as a reducing agent; and, in a third step, isolating the piperidines by distillation.
摘要:
Hydroxybenzaldehydes of the formula (I) are prepared from a benzaldehyde of the formula (II) or its acetal, in which R.sup.1 in the R.sup.1 O-phenyl ether group is an alkyl, cycloalkyl, alkylcycloalkyl or alkylaryl radical, R.sup.2 is H or OH or is identical to R.sup.1 and one or more R.sup.1 O-phenyl ether groups are ortho, meta or para to the aldehyde function, by a process in which a benzaldehyde of the formula (II) or its acetal, in which R.sup.1 and R.sup.2 have the abovementioned meanings and one or more R.sup.1 O-phenyl ether groups occupy the abovementioned position with respect to the aldehyde function, is converted into a hydroxybenzaldehyde of the formula (I) in the presence of water over a zeolite as a heterogeneous catalyst. ##STR1## The catalysts used are, in particular, zeolites of the pentasil type.
摘要:
A process for preparing 2,2,6,6-tetramethylpiperidin-4-one (TAA) is described, whereina mixture comprising acetone and/or acetone condensates and ammonia in a molar ratio of from 20:1 to 3:1at from 50.degree. to 130.degree. C.is reacted in the presence of dimethyl sulfate, the amount of dimethyl sulfate being from 0.5 to 5 mol-%, based on acetone.
摘要:
A process for hydroxylating compounds of the formula ##STR1## where n, A and R.sup.1 to R.sup.4 have the meanings stated in the description, with the aid of microorganisms of the genus Beauveria.
摘要:
A process for the preparation of a 1,4-alkylenediamine of the general formula I ##STR1## in which the substituents R.sup.1 and R.sup.2 are independently hydrogen, C.sub.1 -C.sub.10 -alkyl, phenyl or benzyl, by reacting a succinic dinitrile of the general formula II ##STR2## in which R.sup.1 and R.sup.2 have the meanings stated, with hydrogen at a temperature of from 30.degree. to 250.degree. C. and a pressure of from 50 to 350 bar in contact with a hydrogenation catalyst, wherein the hydrogenation catalyst used contains cobalt oxide and one or more oxides of the elements iron, nickel, manganese, chromium, molybdenum, tungsten, and phosphorus and one or more oxides of elements in the alkali metal group, alkaline earth metal group, and rare earth group of the Periodic Table, and of scandium, and/or of yttrium.
摘要:
A process for the acylation of an alkyl aromatic hydrocarbon with a derivative of carboxylic acid by the Friedel-Crafts method in the presence of a Friedel-Crafts catalyst and an organo-aluminum compound, wherein the organo-aluminum compound is an alumoxane.
摘要:
Esters of optically active 2-arylalkanoic acids I ##STR1## where Ar is an isocyclic or heterocyclic aryl radical and R.sup.1 and R.sup.2 are each C.sub.1 -C.sub.4 -alkyl, are prepared by subjecting an optically active ester II ##STR2## where X is Cl, Br or --O--SO.sub.2 --Y and Y is Cl or a hydrocarbon radical, to a Friedel-Crafts reaction with an aromatic compound ArH (III).
摘要:
Racemic malic acid can be fractionally crystallized, as a diastereomeric salt pair, from alcoholic solution or aqueous-alcoholic solution by using an optical antipode of 2-amino-butan-1-ol.
摘要:
(2R)-1-(Aryloxy)-3-(butyryloxy)-2-propanols of the general formula (I), ##STR1## where Ar is a monocyclic or polycyclic aromatic or heteroaromatic radical, and a process for their preparation by the reaction of (2R)-glycidyl butyrate with an aromatic hydroxy compound Ar--OH in the presence of a quaternary ammonium halide.