Patent ID: 6547933
Filing Date: 2003-04-15
Classification: C07C,Y10S

Abstract:
A process for the purification of a mixture of aromatic polyamines obtained by hydrogenation of corresponding aromatic polynitro compounds, said mixture comprising isomers of said amines as well as reaction by-products, comprising the steps of:a) carrying out a distillation of the mixture in a distillation column wherein a stream of volatile by-products are recovered at the top of the column, b) at the bottom of the column, recovering and separating, a first steam, comprising heavy products and isomers will highest boiling points, c) separating a second stream corresponding to a fraction of the first stream, this fraction representing 2 to 50% of the volume of the first stream, and partially evaporating said second stream to obtain an evaporated portion comprising the isomers with highest boiling points, and a non-evaporated portion, the fraction of the first stream that is not separated as the second stream being used in a phosgenation reaction, d) recovering and recycling the non-evaporated portion in the distillation column, and e) recovering the evaporated portion.