Preparation of colourless dibenzylamine
View Patent ↗The invention relates to a process for preparing colourless dibenzylamine by adding ammonium chlorides or amines to the industrially obtained dibenzylamine and subsequent distillation.
1. Process for preparing colourless dibenzylamine having a colour number of, less than 100 Hazen, comprising adding an additive selected from the group of ammonium chlorides and/or amines to the dibenzylamine to be purified and distilling the resulting mixture.
2. Process according to claim 1 , characterized in that the ammonium chloride corresponds to the following formula:
R 1 R 2 R 3 N—HCl,
where
R 1 , R 2 and R 3 are each independently H or an organic radical,
which is a C1–C6-aliphatic or benzyl radical.
3. Process according to claim 1 , characterized in that the ammonium chloride is benzyl chloride, a hydrochloride, ammonium chloride or aqueous or anhydrous hydrochloric acid, or a mixture of benzyl-/dibenzylamine hydrochlorides.
4. Process according to claim 1 , characterized in that the amine has a higher boiling point than dibenzylamine.
5. Process according to claim 1 , characterized In that the amine is tetraethylenepentamine or distillation residues of tetraethylenepentamine, hexaethyleneheptamine or distillation residues of hexaethyleneheptamine, pentaethylenehexamine or distillation residues of pentaethylenehexamine.
6. Process according to claim 1 , characterized in that the amine is a polyamine from the group of reaction products of dichloroethane with ammonia and/or amines or from the group of reaction products of ethylene oxide with ammonia or amines.
7. Process according to claim 1 , characterized in that the additive is added to the dibenzylamine to be purified in a concentration of 0.01 to 15% by weight based on dibenzylamine.
8. Process according to claim 1 , characterized in that the distillation of the dibenzylamine to be purified has a bottom temperature of 120 to 220° C., and that the pressure is set at a level effective to boil the mixture under the temperature conditions.
9. Process according to claim 1 , characterized in that the resulting pure dibenzylamine is stabilized under nitrogen.
10. Process according to claim 9 , characterized in that the pure dibenzylamine is stabilized by adding aqueous or anhydrous hydrazine or aqueous or anhydrous hydroxylamine.
11. Process according to claim 10 , characterized in that the hydrazine or the hydroxylamine is added to the pure, light-coloured dibenzylamine individually or as a mixture in concentrations of 0.01 to 10% by weight.