Study On The Synthesis And Characterization Of New Schiff Base

Because of the large flexibility and good coordination of macrocycle Schiff base ligands ,the studies on macrocycle Schiff base metal complexes are paid much attention,with lots novel pr-operties showing in medicine,catalysis,analytical chemistry,macrom-olecular chemistry,electrochemistry,etc.Schiff base ligands are de-veloping from simple monodentate ligands to multidentate and m-acrocyclic ligands.So we have synthesized Schiff base L1,L2 andmonodentate Schiff base L3,L4,L5,L6,L7,L8.Their configuration as follows: In the process of synthesis, as furfural susceptible to oxidation, so Synthesis L1, L2, should be under the protection of nitrogen, Sodium hydroxide as catalyst, Returning 4 to 5 hours in methanol solvent, In the synthesis of other compounds L3, L4, L5, L6, L7, L8, not nitrogen protection, the direct use of sodium hydroxide as catalyst, return in methanol solvent. Different product, the response time required for different. Because L-cysteine and L-cystine are not aromatic, so reactions are not easily in the process of synthesis.And the reaction to the conditions required relatively high. Yield is relatively low. However, when one of L-cystine with o-phthalaldehyde synthetic compounds L6, reaction is relatively fast,and the yield is also high.Schiff base compounds stability is rather poor.In high tempe-rature, they are decomposed in the water easily. And the Schiff base of macrocyclic compounds are relatively poor solubility. On-ly compounds L6 can be dissolved in anhydrous methanol, the o-ther macrocyclic compounds have no suitable solvent.We mainly used IR, UV, elemental analysis, and mass spectrometry to characterize the products. In the infrared spectra, the vicinity 1700cm-1 of raw materials aldehyde'sνC=O vibration peak disappears in each compounds,and there is strongerνC=N stretching vibration peaks in 1630cm-1.This shows that the compounds have the C=N bond, which is Schiff base compounds of the main functional groups.In the mass spectra, we can see that reaction of L-cystine and o-phthalaldehyde creates a mixture of L6,and their structures are [1:1], [2:2], [3:3] macrocyclic compounds.