Hoechst Aktiengesellschaft

Peter Horstermann

Klaus Gehrmann

Heinz Erpenbach

Georg Kohl

Reinhard Gradl

Gunter Roscher

Erhard Jagers

Klaus Eichler

Hans-Klaus Kubbeler

Horst Langner

Karl-Heinz Schmidt

Erpenbach Heinz

Iodine and its compounds are separated from the carbonylation products acetic acid, acetic anhydride or ethylidene diacetate obtained on subjecting dimethylether, methyl acetate or methanol to a carbonylation reaction in the presence of an iodine-containing catalyst. The quantity of total iodine contaminating the carbonylation products is reduced to less than 20 ppb iodine by treating the products at 20.degree.-200.degree. C. with peracetic acid, diacetyl peroxide or a compound yielding these two agents under the reaction conditions, and separating them distillatively.

Process for separating iodine and its compounds from the products

The invention relates to a process for the isolation of vinyl acetate which involves not combining the bottom product of the recylced gas washings with the water-saturated vinyl acetate but rather introducing it to further multiple distillation columns from the gas mixture formed in the reaction of ethylene with acetic acid and oxygen over catalysts containing palladium or palladium compounds in the gas phase.

Process for the isolation of vinyl acetate by distillation

In order to prepare phenylalanine n-propyl ester hydrochloride, phenylalanine hydrochloride is reacted with n-propanol in the molar ration 1: (5 to 20) at temperatures from 80.degree. to 110.degree. C., preferably 85.degree. to 105.degree. C., at pressures from 0.1 to 1.5 bar in the presence of 0.1 to 0.75 mole of HCl/mole of phenylalanine hydrochloride as catalyst and in the presence of water entrainer, a concentration of water entrainer of 20 to 50% by weight being maintained in the reaction mixture.

Process for the preparation of phenylalanine n-propyl ester hydrochloride

In the process for the preparation of N-acetylphenylalanine by opening the ring of 2-methyl-4-benzylidene-1,3-oxazolin-5-one with water to give 2-acetaminocinnamic acid and subsequently catalytically hydrogenating the latter, both reaction stages are carried out in a mixture of an aliphatic C.sub.3 -ketone to C.sub.10 -ketone or a water-miscible ether and water as the solvent, and the hydrogenation of the 2-acetaminocinnamic acid is carried out at temperatures of 10.degree. to 50.degree. C. and pressures of 1 to 15 bar in the presence of a supported palladium catalyst.

Process for the preparation of n-acetylphenylalanine

A process for removing by product acetone from reaction mixtures obtained by reacting methyl acetate and/or dimethylether with carbon monoxide at elevated temperatures to obtain acetic anhydride in the presence of a catalyst system consisting essentially of carbonyl complexes of noble metals belonging to group VIII of the Periodic System of the elements, acetic acid, an organophosphorus or organonitrogen compound, and methyl iodide whereby the acetone obtained as a by-product during the reaction is subjected to condensation at temperatures of 50.degree. to 250.degree. C., under pressures of 0.01 to 150 bars and at a molar ratio as above defined for the catalyst system constituent of 1:(25-500):(10-100):(15-150) so as to obtain predominantly higher-boiling secondary products to be distillatively separated in a successive distillation zone together with volatile constituents of the catalyst system.

Process for removing acetone from reaction mixtures of carbonylation

The disclosure relates to a process for separating the catalyst system from reaction mixtures which are obtained by reacting methyl acetate and/or dimethylether with carbon monoxide and optionally hydrogen at elevated temperatures to acetic anhydride and optionally ethylidene diacetate in the presence of a catalyst system consisting of carbonyl complexes of noble metals belonging to group VIII of the Periodic System, acetic acid, an organophosphorus or organonitrogen compound, methyl iodide and optionally compounds of carbonyl-yielding common metals, and which issue from the reaction zone under a pressure of 25 to 150 bars at a temperature of 100.degree. to 250.degree. C. More particularly, the reaction mixture coming from the reaction zone is introduced into a separator heated to 60.degree. to 140.degree. C. and released to a pressure of 0.5 to 3.5 bars with spontaneous evaporation of the bulk of volatile constituents; the stream of liquid matter coming from the separator is delivered to a distilling zone and the bulk of still volatile constituents is distilled off therein under a pressure of 0.05 to 1 bar at a base temperature of 70.degree. to 170.degree. C.; and catalyst solution retained as base product is recycled to the reaction zone.

Growing community of inventors

Erftstadt, Germany

Peter Horstermann