有机氟化学1.doc

有机氟化学 氟元素: “化学元素中举足轻重的小个子”原子电负性(Pauling)Pauling原子半径 ()Bondi原子半径 （)键能 (CH3-X)(kcal/mol)键长CH3-X()H2.11.201.20991.09F4.01.351.471161.39Cl3.01.801.75811.77Br2.81.951.85681.93O (OH)3.51.401.52861.43S (SH)2.51.851.80651.82尖端材料：在军用尖端材料中，含氟材料占近一半（由于其独特优异的稳定性和其它物理特性）； 医药农药：最近报道，全球新注册的医药中10含有氟元素；新注册的农药中，40含有氟元素。 有机氟化学起源有机含氟材料（包括有机含氟化合物、调聚物、聚合物）的起源可以上溯到19世纪后期。1886年法国化学家Moissan首次分离出了单质氟，随后经过了19世纪30年代的氟利昂的发现，40年代曼哈顿计划氟材料的大量使用，才在50年代以后逐渐发展成为既有浓厚学术性又有极强应用性的一门学科。经过了100多年的曲折发展道路，有机氟材料领域不断得到提高，深刻影响了全球经济发展和社会进步。氟化学发展中的里程碑 1886年 Moissan分离得到单质氟； 1892年 Swarts发现了三氟化锑作用下的氯/氟卤素交换反应； 1928年 Midgley发明了“氟利昂”; 1938年 Plunkett发现了聚四氟乙烯，标志着含氟聚合物的诞生； 1947年 Fowler发现了三氟化钴作用下的全氟化方法； 1949年 Simons发现了电化学氟化方法； 1954年 Fried对有机含氟物质在医学上的应用的研究； 1962年 George Olah利用含氟物质首次发现稳定的碳正离子存在； 1962年 Bartlett发现了惰性气体的氟化（XePtF6）； 1974年 Molina和Rowland对某些氟利昂破坏臭氧层的研究； 1979年 Margraves发现了直接氟化； 2003年 OHagan分离出了第一个氟化酶。BIOCHEMICAL FLUORINE The biosynthetic pathway to fluoroacetate and 4-fluorothreonine in the bacterium S. cattleya involves a fluorinase-catalyzed CF bond formation in the first step shown here. The intermediate metabolites shown have been identified, but in some cases (indicated by dashed arrows) the enzymes involved remain to be isolated. Fluorine Chemistrys Uncharted Territory(1) Coordination or metathesis polymerization methods, such as Ziegler-Natta-type reactions carried out on ethylene and propylene, have been unsuccessful With fluoroolefins, Smart said. These fluorinated monomers typically are too unreactive because they have highly electron-deficient double bonds. If they do react, metal fluoride elimination is a problem. These circumstances have limited commercial polymerizations to free-radical processes. Its also difficult to tailor high-molecular-weight block copolymer structures with fluoroolefins, he added. (2) Fluoroolefin polymerization is still based largely on developments from the 1950s, he pointed out, while there have been myriad changes for hydrocarbon polymerizations, particularly in catalyst design and living polymerization capabilities. That means there are many opportunities for fluoropolymers, and there are “little pieces of evidence” in the chemical literature to suggest that organometallic chemistry involving late-transition metals with the right type of ligands could make a difference. “This is an encouraging area for chemists to think about,” he said.(3) Smart also mentioned efforts to replace fully fluorinated alkane surfactants, such as perfluorooctyl carboxylates and sulfonates that are used in polymerization processes. These compounds and their precursors are under scrutiny as persistent molecules that accumulate in the environment. “I think in the next few years we will see a lot of work to find replacements,” Smart said. “Its possible, with the right design, that some of these materials can be lightly fluorinated and still express the surface activity of the long-chain surfactants.”(4) Another interesting prospect he noted is direct fluorination reactions using fluorspar (CaF2), which