近临界水介质中若干有机反应的研究及应用

Abstract：Organic reactions carried out in water have received much more attention in last decade because of the cheap, nonflamble and nontoxic properties of water. Unfortunately, the limitation of water as solvent in organic synthesis is its poor dissolving ability for most organic compounds at ambient temperature. On the other hand, the unique properties of water near its critical point (Tc = 374 oC, Pc = 221 bar) have promoted researchers to use it instead of organic solvents in organic synthesis. As water is heated towards its critical point, it changes from a polar liquid to an almost non-polar fluid. Its dielectronic constant ε decrease from 78.5 at room temperature to 20 at 275 oC, favoring the solubility of organics and ions. Its dissociation constant, Kw, increase several orders of magnitude from ambient to near-critical conditions (Kw = 10-11 at 275 oC), providing hydronium and hydroxide ions that can acts as modest acid or base in chemical reactions. Although much of supercritical water research has been focused on the total oxidation of organic compounds and geochemical modeling, there are increasing number of papers which suggest that near-critical water (250-325 oC) used as excellent solvent for organic reactions because organic reactions in near-critical water offer many advantages over those in traditional organic solvents. For example, it is environmentally benign and also easy for product separation..This project mainly have studied on the reduction of organic nitro compounds and azides to the corresponding amines by metallic zinc, iron and tellurium powder in near-critical water, a novel two-step aldehyde homologation procedure for the preparation of methyl ketone involves the use of 1,1-dibromo-1-alkene as precursor and zinc metal as mediator in near-critical water, a Glaser coupling of terminal alkynes in the presence of nickel (II) chloride and copper(II) chloride in near-critical water, a novel reduction of sodium alkyl thiosulfates using samarium metal without activating agent in hot water, a ligandless palladium chloride catalyzed homo-coupling of arylboronic acid in aqueous media and a Sonogashira coupling reaction of aryl iodides, bromides and terminal alkynes with palladium powder, potassium fluoride in aqueous media..Twenty-two scientific papers about this project have been finished including 14 journal papers and 8 meeting papers. They have been published in Tetrahedron Letters or to be published in Tetrahedron Letters, Synthetic Communications, Phosphorus, Sulfur, Silicon et al. One national patent application has been accepted by State Intellectual Property Office of China. Our research has won the Second-Class award for Progress in Science and Technology of Huaibei, Anhui province and the First-Class award of poster paper presented in 12th National Conferences of Organometallic Chemistry in China.

研究在近临界水介质中金属锌、钐促进的巴比尔、迈克尔、还原偶联及环化反应和钯催化的碳碳键偶联及胺化反应，并应用于天然产物及聚合物的合成中。由于近临界态水的独特性质，用它作为有机合成反应介质，不仅对环境友好，而且可减少三废的生成，节省资源与能源，是一理想的绿色化学。并期待在近临界态水介质中具有特殊性能的聚合物材料生成。..