Process for preparing para-phenylenediamine derivatives
AssigneeUniroyal Chemical Company, Inc.
InventorsMichael Reynolds, Russell E. Malz
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Abstract
An improvement in a process for the preparation of a p-aminodiarylamine by reduction of the corresponding nitroso or nitro compound with hydrogen in a hydrogenator in the presence of a catalyst is disclosed. The invention includes equipping the hydrogenator with filtration means capable of separating the p-aminodiarylamine product from the catalyst, whereby the p-aminodiarylamine product can be removed from the hydrogenator while the catalyst is retained therein, thereby permitting the reaction to be run semicontinuously or continuously.
Claims23
In a process for the preparation of a p-aminodiarylamine by reduction of the corresponding nitroso or nitro compound with hydrogen in a hydrogenator in the presence of a catalyst, the improvement that comprises equipping the hydrogenator with filtration means capable of separating the p-aminodiarylamine product from the catalyst, whereby the p-aminodiarylamine product can be removed from the hydrogenator while the catalyst is retained therein, thereby permitting the reaction to be run semicontinuously or continuously.
The process of claim 7 wherein the filtration means further comprises a dip stick to which the filtration device is attached.
In a process for the preparation of p-aminodiphenylamine by reduction of p-nitrosodiphenylamine, sodium salt with hydrogen in a hydrogenator in the presence of a catalyst, the improvement that comprises:
- (a) equipping the hydrogenator with filtration means capable of separating the p-aminodiarylamine product from the catalyst, whereby the p-aminodiarylamine product can be removed from the hydrogenator while the catalyst is retained therein, thereby permitting the reaction to be run semicontinuously or continuously, said filtration means comprising a recirculation loop installed onto the reactor to provide means for reactor contents to be removed continuously and passed through a filtration system whereupon the catalyst and a portion of the product are returned to the reactor and a portion of the catalyst-free product is removed, whereby the correct level of catalyst is maintained in the reactor;
- (b) employing palladium supported by carbon as the catalyst;
- and
- (c) running the reaction under a pressure of about 200 psig and at a temperature of about 60.degree. C. in the presence of toluene.
Dependencies are inferred from the claim text.