United States Patent Office
Patented Feb. 11, 1947 2,415,786 UNITED STATES PATENT OFFICE UNSYMMETRICALLY SUBSTITUTED PPERAZINES Johannes S. Buck, East Greenbush, and Richard Baltzly, New York, N. Y., assignors to Bur roughs Welcome & Co. (U. S. A.) Inc., New York, N.Y., a corporation of New York No Drawing. Application January 6, 1944, serial No. 517,224 9 Claims. (C. 260-268) 2 This invention relates to N-monosubstituted According to the present invention, these diffi and N-N'-unsymmetrically disubstituted piper culties are overcome by treating piperazine with azines and has for an object to provide new com a halide of benzyl or of a substituted benzyl to positions of the above type and a novel and im form a reaction mixture containing, in addition proved method of making the same. to unreacted piperazine and di-N-N'- Substituted Another object is to provide a method of mak piperazine, a substantial amount of N-mono sub ing and isolating the above substances which is stituted piperazine separating the mono-N-sub Suitable for commercial Operation. stituted piperazine from the unreacted piperazine In our copending application Serial No. 476,914, and the disubstituted piperazine, introducing the filed February 24, 1943, of which the present ap O desired substituent on to the second N' nitrogen plication is a continuation in part and in our atom of the mono-N-substituted piperazine, then Copending application Serial No. 517,225, filed removing the benzyl or substituted benzyl group January 6, 1944, which is also a continuation in by catalytic hydrogenation. part, We have described certain methods for mak As catalysts for this hydrogenation, platinum, ing and isolating substituted piperazines of the palladium and nickel are all suitable, but We pre type fer in general to use palladium since, while CEI-CI equally or perhaps more effective in removing a benzyl group, it is practically devoid of any N /N-R tendency to reduce aromatic rings.
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