Patent ID: 7915452
Filing Date: 2011-03-29
Classification: C07C

Abstract:
1. A method of producing xylylenediamine from xylene, which consists of: (1) an ammoxidation step in which xylene is allowed to react with ammonia and oxygen in a vapor phase in the presence of a V—Cr—B—Mo-containing-catalyst, thereby obtaining an ammoxidation gas containing dicyanobenzene; (2) an extraction step in which the ammoxidation gas is bought into contact with an organic solvent comprising methylbenzonitrile, thereby extracting dicyanobenzene into the organic solvent to obtain a dicyanobenzene-containing solution; (3) a distillation step, in a distillation column, in which the dicyanobenzene-containing solution from the extraction step is distilled to be separated into the organic solvent and dicyanobenzene by recovering the organic solvent together with methylbenzonitrile by-produced in the ammoxidation step (1) from the top of the column and taking out dicyanobenzene from the bottom of the column; (4) a hydrogenation step in which, after adding a reaction solvent, the separated dicyanobenzene from the distillation step is hydrogenated in a liquid phase in the presence of a Ni/diatomaceous earth catalyst to obtain a solution containing xylylenediamine; and (5) a purification step in which the solution containing xylylenediamine from the hydrogenation step is distilled to obtain a highly pure xylylenediamine, wherein: (i) said distillation step (3) is performed in a single distillation step in a single distillation column; (ii) the temperature of the column bottom in the distillation step (3) is 165 to 200° C.; (iii) the distillation column is operated under a pressure of 3 to 20 kPa during said distillation step (3); and (iv) at least a part of the organic solvent separated in the distillation step (3) is reused in the extraction step (2).