2 - Formyl -8 - Hydroxyquinoline Shrink Synthesis And Theoretical Study Of Aromatic Amine Schiff Base

Quinoline derivatives are very important in chemistry, as well as in the fields of medicine, biology, and materials. As chemical analysis reagents, they are used in the metallurgical industry in the analysis of metal elements. In the pharmaceutical industry, they are widely used as drug intermediates. The researches of quinoline derivatives are related to biochemistry, biophysics, medicinal chemistry and other fields, and have been of great importance to many scientific workers. As an important quinoline derivative,2-formyl-8-hydroxyquinoline also has important use. In the present study, we successfuly synthesized 2-formyl-8-hydroxyquinoline and its crystal, and then react with six kinds of aromatic amine respectively. At last, We get six kinds of Schiff base and two crystals, and characterized crystals through X-ray diffraction methods and computational chemistry methods. We hope that what we have done can be useful to the research of quinoline derivatives.ChapterⅠ:We introduced the synthetic reaction mechanism of Schiff base and the research progress in recent years, and showed the purpose and significance of the present study. The important role of Schiff base played in analytical chemistry, coordination chemistry, material chemistry, medicine, and other fields were outlined. Therefore, the purpose and significance of our study was given.ChapterⅡ:2-Formyl-8-hydroxyquinoline was prepared by acetylation (acetic anhydri de) of hydroxyl group, followed by oxidation (SeO2) of methyl group, using 2-methyl-8-hydroxyquinoline as the starting material. Six kinds of new Schiff base compounds were synthesized by condensation of 2-formyl-8-hydroxyquinoline with substituted anilines. All the compounds were characterized by IR, UV, and 1H NMR. The crystal structures of two kinds of Schiff base compounds were measured by single x-ray diffraction. It is found that the two compounds have similar crystal structures with crystal system being orthorhombic and space group being P-1. The quinoline ring and benzene ring are not coplanar, and Schiff base CH=N bond is only coplanar with quinoline ring, which indicate that C=N bond conjugate with quinoline ring only. It is also found thatπ-πstacking interactions are existed between molecules.ChapterⅢ:Theoretical calculation was performed to study the structures, spectral properties, and intramolecular proton-transfer reactions of two Schiff base compounds (L2 and L3), by density-functional B3LYP calculations using the 6-31++G** basis set. The calculation results were compared to these obtained in the experimental research. The optimized stable geometry of L2 is not planar and the optimized stable geometry of L3 is planar. The optimized stable geometry of L2 is not consistent to the x-ray single crystal structure of L2. The bond lengths, bond angles, IR vibration frequencies and NMR signals are congruent with the experimental measurements. The study of the intramolecular proton-transfer reactions of the Schiff base compounds shows that the intramolecular proton-transfer reactions are endothermic processes, and the stability of the products of proton-transformation is lower than that of Schiff base compounds before proton transfering.