Preparation And Properties Of Bis-salicylaldehyde Ethylenediamine Schiff Base Derivatives

N,N’-bis(2-hydroxybenzyl)ethylenediamine-N,N’-diacetic acid (HBED) is a new generation of metal ion ligands due to its unique structure and properties. HBED and its derivatives are widely used in many fields such as medicine, fertilizer, functional polymer and polyurethane additives. In this thesis, salicyladehyde and ethyenediamine are used as the raw materials to get products HBED, Fe(Ⅲ)-HBED chelate and N,N’-bis(2-hydroxybenzyl)-ethylenediamine-N,N’-dihydroxyethyl (HBEDH). Furthermore, polyurethane elastomer is prepared using HBEDH as crosslinking agent and reactive catalyst. The main research content as follows:Firstly, the bis-salicylaldehyde ethylenediamine schiff base was prepared by salicyladehyde and ethyenediamine in the ethanol and the yield ran up to 95.3%. The Schiff base was reduced by using sodium borohydride as reducting agent to get N,N’-bis(2-hydroxybenzyl)ethylenediamine (HBE) and the yield reached 68.3%. Under the codition of ice bath, the tert-butyl bromoacetate was added to the mixed solution of DIPEA, DMF and HBE to get product N,N’-bis(2-hydroxybenzyl)-ethylenediamine-N,N’-tert butyl diacetate (HBETD) and yield reached 77.9%. HBED was synthesized by employing the transesterification reaction of formic acid and HBETD. The structures of intermediate and final products in the process of synthesis of HBED were characterized by infrared spectroscopy (IR), nuclear magnetic resonance spectra (’H-NMR), mass spectrometry (MS), and melting point determination to verify the accuracy of the target product. The chelating compound of HBED and Fe3+ was synthesized by dropping ethanol aqueous solution of FeCl3·6H2O into ethanol aqueous solution of HBED and staying solvent evaporation under the condition of room temperature until the reddish-brown solid to be obtain. The structure of chelate was characterized by IR、1H-NMR and UV.Then a novel polyurethane crosslinking agent HBEDH was prepared by reducing reaction of HBETD in the presence of LiAlH4. A series of polyurethane elastomers with different content of crosslinking agent were polymerized from polyether polyol (PTMG2000) and toluene diisocyanate in the presence of HBEDH as the crosslinking agent and reaction catalyst. The study on their physical property, thermal property, dielectric property and dynamic mechanical property indicated that their properties were significantly related with the content of crosslinking agent. The rigidity, tensile strength and dielectric constant of polyurethane elastomer decrease with the increase of crosslinking agent.