Patent DE-19613555-A1 (DE)
Title: Integrated production and fractionation of aromatic poly:amine mixtures
Inventor: KNOEFEL HELMUT DR
IPC: C07C211/50
Filed: 1996-04-04
Abstract: A process for the production of aromatic polyamine mixtures (I) with integrated fractionation and/or purification, by reacting aryl amines (II) with carbonyl compounds, especially formaldehyde (III), in presence of acid catalysts (IV) and water (at least in the last stage of the rearrangement), and optionally in series with a separate "aminal stage" to form N,N'- disubstituted condensation products in the absence of (IV) and optionally in presence of hydrophobic solvents (V). In this process, (a) the 2-phase reacted mixture (01), optionally (b) after adding (II) and/or water and/or strong acid (as salts of (II) and possibly (I)), preferably in the form of a recycled aqueous phase (06, 09 and/or 07), and optionally (c) after adding hydrophobic solvent (V) which may contain (II) and/or (I), is (d)/(e) separated in stage C-1 into organic (03) and aqueous phase (02). The aqueous phase (02) is (f) taken to multi-stage counter-current extraction (stage C-2) with an organic phase containing (V), (II) and possibly small amounts of (I). The aqueous phase obtained from C-2 (06, which is free from I), optionally (g) after removing water by distillation in stage (C-4) and optionally (h) after removing amine and increasing the level of protonation by extraction in stage (C-3), is (i) at least partly returned to the reaction process, any remaining being used as in (b). The organic phases (03) and (05) from stages C-1 and C-2 are taken separately to part-stages D-21 and D-22 of extraction stage D-2 and extracted successively with an aqueous phase (11) containing water, strong acid (as ammonium salt), (II) and possibly (I), this phase being adjusted to give the required controlled partition of (I) between the resulting organic (12) and aqueous (13) phases and the required different composition of the resulting polyamine fraction. Organic phase (12), (l) optionally after separating off part and returning it directly or preferably via extraction stage D-1, is (m) washed and/or neutralised and then separated by distillation, preferably in a multi-stage system (E-3)/(E-4), into first distillate fraction(s) (14) containing (V) and possibly (II), possibly a second fraction containing (II) and possibly (V), and a residue (16) comprising the first polyamine fraction (I). Aqueous phase (13) from D-22 is (n) optionally passed through an intermediate extraction stage D-3 and then (o) extracted in stage D-4) with an organic phase (18) containing (V) and (II), so that polyamine (I) is largely transferred to the organic phase (17); the polyamine-free aqueous phase is (p) optionally at least partly evaporated, (q) optionally extracted to remove amine and increase the degree of protonation, (r) optionally passed through a prior extraction stage (D-1) and (s) returned to extraction stage D-21. The organic phase (19) from D-4 is taken via a washing and/or neutralisation stage to optionally multi-stage distillation (F-3) and separated into fraction(s) (20) containing (V) and (II) and a second polyamine fraction (residue 19).