Patent ID: 7989662

Claim:
A method for of refining an organic composition comprising 4-aminodiphenylamine, aniline, azobenzene, and phenazine, comprising: applying the organic composition to a first rectification column; producing a first effluent composition at the top of the first rectification column and a second effluent composition at the bottom of the first rectification column, wherein the first effluent composition comprises aniline, azobenzene, and phenazine, and wherein the second effluent composition comprises 4-aminodiphenylamine; applying the second effluent composition to a second rectification column; and producing a 4-aminodiphenylamine composition at the top of the second rectification column and a residual composition at the bottom of the second rectification column, wherein the first rectification column is operated at a vacuum degree ranging from about 0.09 to about 0.098 MPa, a reflux ratio of from about 2:1 to about 10:1, a column top temperature of from about 80° C. to about 130° C., and a still temperature of from about 260° C. to about 290° C.