Abstract:
The process for separating off rare metal catalysts used in the preparation of ether-carboxylic acids by catalytic oxidation with a suspended catalyst comprises carrying out a crossflow filtration and pretreating the filter elements used with a medium which is not solid under the treatment conditions and is composed of one or more carboxylic acids.
Abstract:
The present invention relates to a process for the preparation of compounds of the formula ##STR1## in which R.sup.1 is --CN, --COOH, --COOR', R' being an organic radical having 1 to 6 carbon atoms, --CONH.sub.2, --COCl or --CHO and R.sup.2 is H or Cl, which comprises reacting a compound of the formula ##STR2## in which R.sup.1 is as defined above and R.sup.3 is H or Cl, with a chlorinating agent in the presence of a chlorination catalyst at -10.degree. to 200.degree. C.
Abstract:
Compounds of the formula(R.sup.11 Re).sub.k O.sub.1 R.sup.12 .sub.m .multidot.L.sub.n (III)in whichR.sup.11 is a hydrocarbon group which is bonded to the rhenium via a carbon atom to which at least one hydrogen atom is still attached,R.sup.12 is aliphatic hydrocarbon radical which may contain silicon bridge atoms, or is an unsubstituted or substituted phenyl radical,L is a ligand which is bonded to the rhenium metal via one to three oxygen and/or nitrogen atoms, and theindex k is 1 or 2, the index 1 is an integer from 1 to three times k, the index m is zero or an integer from 1 to twice k, and the index n is an integer from 1 to three times k, and in which the indices k, l, m and n are selected such that their combination satisfies the 5-, 6- or 7-valence of rhenium.The invention also provides compounds of the formula(polymer).sub.f .multidot.(CH.sub.3 ReO.sub.3).sub.8 (VI)in which the rhenium compound CH.sub.3 ReO.sub.3 is bonded to the polymer via amine or amide nitrogen in the polymer. It further provides for the use of compounds of the formula R.sup.1.sub.a Re.sub.b O.sub.c (I) in which a is 1 to 6, b is 1 to 4 and c is 1 to 14 and the total of a, b and c is such that the 5-valence to 7-valence of rhenium is satisfied, with the proviso that c is not greater than three times b, and in which R.sup.1 represents an optionally fluorinated hydrocarbon, or of compounds of the formula (R.sup.11 Re).sub.k O.sub.l R.sup.12.sub.m .multidot.L.sub.n (III) or (polymer).sub.f .multidot.(CH.sub.3 ReO.sub.3).sub.g (VI), as catalysts for the oxidation of multiple C--C bonds and also provides processes of this type.