Abstract: The process for the preparation of monocarboxylic anhydrides of the general formula (RCO).sub.2 O is carried out by reacting a carboxylic ester or a dialkyl ether of the general formula RCOOR or ROR, in which R in each case denotes the same alkyl radical having 1 to 4 carbon atoms, with carbon monoxide in the gas phase in the presence of a supported catalyst. The reaction takes place by means of bromine or iodine or compounds thereof as reaction promoter. The support material in the catalyst supports a noble metal chelate compound which is formed by a noble metal compound from group VIII of the periodic table and a chelating agent containing organonitrogen, organophosphorus, organoarsenic, organosulfur or mercapto groups and substituted in its basic structure with alkyl, aryl or aralkyl groups. The reaction is carried out at temperatures from 130.degree. to 400.degree. C. and pressures from 1 to 150 bar.

Abstract: In the process for the preparation of monocarboxylic anhydrides of the general formula (RCO).sub.2 O by reacting a carboxylic acid ester of dialkyl ether of the general formula RCOOR or ROR, where R in each case denotes the same alkyl radical having 1 to 4 carbon atoms, with carbon monoxide in the gas phase in the presence of iodine or bromine or compounds thereof as reaction promoter, and in the presence of a supported catalyst, at temperatures of from 130.degree. to 400.degree. C. and pressures of from 1 to 150 bar, where, in the supported catalyst, an organosilicon compound is bonded, as a polyfunctional coupling agent, on the one hand to a support material and on the other hand to a noble-metal compound from group VIII of the Periodic Table, a chelate-forming organosilicon compound of the general formula ##STR1## is employed as the polyfunctional coupling agent, where X=Cl, Br or --OR.sup.2 ;Y=-NR.sub.2.sup.4, a nitrogen-containing aryl radical, --PR.sub.2.sup.4, AsR.sub.2.sup.4, --SR.sup.

Abstract: Disclosed is a process for recovering rhodium catalyst values from "tars" formed during the preparation of acetic anhydride by the rhodium catalyzed carbonylation of a mixture of methyl iodide and methyl acetate and/or dimethyl ether. The disclosed process provides a means for the recovery of rhodium values which normally are not extracted from the tars by treating a methyl iodide solution of such tars with certain oxidants.

Abstract: A process for the production of organic carboxylic acids by the catalytic reaction of organic formate esters in contact with carbon monoxide and a homogeneous catalyst system of rhodium metal atom, a phosphorus containing ligand in which there is present at least one oxo oxygen atom attached to a phosphorus atom or a carbon atom to form a Z group and the ##STR1## group in said Z group is located at least one carbon atom removed and preferably from 2-4 carbon atoms removed from the phosphorus atom of the molecules represented by the formulas ##STR2## and a halogen source, under mild reaction conditions, wherein R' is H, aryl, alkaryl, aralkyl or alkyl, and wherein 1 or more of said R' groups can be substituted with a Z group but not more than 3 of said R' groups in the molecule are so substituted; a is an integer from 0-4; b is an integer from 0-3; and Z is P(O)R'R'; --C(O)OR" or C(O)R", wherein R" is R'.

Abstract: Organic iodine compounds are separated from carbonylation products of methanol, methyl acetate and dimethyl ether and from mixtures of such carbonylation products by a process wherein the iodine compounds are removed by liquid phase extraction with a non-aromatic hydrocarbon.

Abstract: Monocarboxylic anhydrides of the general formula (RCO).sub.2 O are made by reacting a carboxylic acid ester or dialkylether of the general formulae RCOOR and ROR, respectively, in which R stands for one and the same alkyl radical having from 1-4 carbon atoms, with carbon monoxide in gas phase, in the presence of iodine or bromine or their compounds as a reaction promoter and also in the presence of a carrier-supported catalyst containing noble metal compounds of group VIII of the Periodic System, at temperatures of 130.degree.-400.degree. C. and under pressures of 1-150 bars. To this end, a novel carrier-supported catalyst is used in which the carrier material has a noble metal/chelate-compound formed of the noble metal compound and a chelator containing organonitrogen, organophosphorus, organoarsenic or organosulfur groups applied to it.