1. Research On The Synthesis Of Dimethyl Carbonate And Its Synthetic Mechanism In The Presence Of Ionic Liquid 2. The Synthesis And The Theoretical Study On The Structure And Properties Of Four Monomethine Cyanine Dyes And One Styryl Dye

This paper contains two parts: (i) Research on the synthesis of dimethyl carbonate and its synthetic mechanism in the presence of ionic liquid; (ii) The synthesis and theoretical study on the structure and properties of four monomethine cyanine dyes and one styryl dye.Part i: Research on the synthesis of dimethyl carbonate and its synthetic mechanism in the presence of ionic liquid.Dimethyl carbonate is a non-toxic, environmental friendly, and broadly utilized chemical material with great market potential. It is honored as the cornerstone of organic synthesis in the 21st century.In this paper, the basic property,application situation and new synthesis technology of dimethyl carbonate (DMC) are briefly introduced. A new direct synthesis technique of dimethyl carbonate from methanol,potassium carbonate and carbon dioxide etc. in the presence of ionic liquids under mild conditions is designed in this paper. Six kinds of ionic liquids (BmimBr,BmimBF₄,BmimPF₆,PmimBr,PmimBF₄,PmimPF₆) are prepared and their viscosity are also determined, respectively. The possible formation mechanism and the reaction conditions of DMC are studied under the assistance of GC-MS, and the yield of DMC is successfully improved. In addition, this new direct synthesis technique is also successfully extended to the synthesis of some other symmetric carbonates, and the yields of three carbonates rised up to more than 60%.Part ii: The synthesis and the theoretical study on the structure and properties of four monomethine cyanine dyes and one styryl dye.The application of monomethine cyanine dyes with indole nucleus and styryl dyes in the areas of CD-recording and biological fluorescence detection has been gaining more and more attention all over the world. The density functional theory/time-dependent density functional theory (DFT/TD-DFT) theories, which can accurately predict the molecular structure,electronic spectrum,chromatic mechanism and the non-linear optical property of dyes, has become the most widely used calculation program by the chemists. The molecular structure and the application situation of the two kinds of dyes in this work are briefly introduced. The concepts of DFT/TD-DFT theories and self-consistent reaction field are simply explained. The theoretical research progress of the molecular structure and spectrum properties of the two kinds of dyes are also presented in this paper.A series of monomethine cyanine dyes with indole nucleus are prepared from indoline and 2-methylthio quinoline quaternary salts in the solvent of anhydride under nitrogen protection. The structures of dyes are confirmed by ¹H NMR, ¹³C NMR, IR, UV-Vis, MS, and studied by DFT/TD-DFT method, respectively. The absorption of dyes in different solvents is optimized by a muti-linear regression model, and the relative deviation ofλ_max is in the range of -0.35%～-5.6%. The frontier orbital distribution analysis shows that the UV-Vis absorption spectrum derives from theπ→π^* transition. In addition, the IR spectrum of one dye was calculated and the results are in good agreement with the experimental value.A kind of 2-styryl-β-naphthathiazole dye is prepared according to the reported literature and confirmed by X-ray diffraction technique, ¹H NMR, IR, UV-Vis and MS. The crystal structure and the spectrum property of it are studied by theoretical method (DFT/TD-DFT). The result shows that all of the theoretical ways chosen in this work can accurately reproduce the experimental data of this styryl dye.