格氏反应
Grignard reaction (pronounced /ɡriɲar/ ) is an organometallic chemical reaction in which alkyl - or aryl - magnesium halides练达的意思 ( Grignard reagents ) act as nucleophiles and attack electrophilic carbon atoms that are prent within polar bonds (eg in a carbonyl group as in the example shown below) to yield a carbon–carbon bond, thus altering hybridization about the reaction center. [ 1 ]香江丽景 The Grignard reaction is an important tool in the formation of carbon–carbon bonds [ 2 ] [ 3 ] and for the formation of carbon– phosphorus如何查找ip地址 , carbon– tin , carbon– silicon , carbon– boron and other carbon– heteroatom bonds. 格氏反应 （发音为/ɡriɲar/）是一种有机金属 化学反应中烷基 -或芳基 - 镁 卤化物 （ 格氏试剂 ）作为亲核攻击电碳原子存在于极性键 （如在一个羰基本集团在例如图所示），以产生的碳碳键，从而改变杂交反应中心有关。 [1]的格氏反应是形成的重要工具，在碳碳键 [2] [3]和形成的碳- 磷 ，碳， 锡 ，碳， 硅 ，碳， 硼和其他碳杂债券。
The nucleophilic organometallic addition reaction is irreversible due to the high pK a value of the alkyl component (pK a = ~45).亲核加成反应是不可逆的有机由于高峰组件值的烷基（峰一 =〜45）。 Such reactions are not ionic; the Grignard reagent exists as an organometallic cluster (in ether).这种反应是不是离子;格氏试剂作为有机金属簇（乙醚）存在。
The disadvantage of Grignard reagents is that they readily react with protic solvents (such as water), or with functional groups with acidic protons, such as alcohols and amines.格氏试剂的缺点是，他们随时反应僖负羁质子溶剂 （如水），或功能组别酸性质子的胺，如醇类和。 In fact, atmospheric humidity in the lab can dictate one's success when trying to synthesize a Grignard reagent from magnesium turnings关羽传 and an alkyl halide .事实上，该实验室的大气湿度可以决定一个人的成功时，试图从镁合成格氏试剂转弯战国七雄地图和烷基卤化物 。 One of many methods ud to exclude water from the reaction atmosphere is to flame-dry the reaction vesl to evaporate all moisture, which is then aled to prevent moisture from returning.用于排除在大气中的水反应许多方法之一是火焰干燥反应容器蒸发所有水分，然后将其密封，防止水分返回。 However, though the reagents still need to be dry, ultrasound can allow Grignard reagents to form with less stringent regard to the amount of water in the reaction mix by activating the surface of the magnesium such that it consumes any water prent. [ 4 ]然而，尽管仍然需要的试剂干燥，超声波可以让格
氏试剂混合形成宽松的反应，这方面的量水在通过激活镁表面的，这样它消耗任何水存在。 [4]
Another disadvantage of Grignard reagents is that they do not readily form carbon–carbon bonds by reacting with alkyl halides via an S N 2 mechanism.格氏试剂的另一个缺点是，它们不容易形成的 N 2机理碳一，碳卤化物通过债券与烷基反应。
Grignard reactions and reagents were discovered by and are named after the French chemist François Auguste Victor Grignard ( University of Nancy , France) who was awarded the 1912 Nobel Prize in Chemistry for this work.格氏试剂反应和发现并命名的法国化学家弗朗索瓦奥古斯特维克多格氏 （ 南希大学 ，法国）谁是1912年荣获诺贝尔化学奖 ，对这项工作。
Contents内容 [hide] 1 Reaction mechanism 1 反应机理 2 Preparation 2 准备 o Initiation 启动 o Industrial production 工业生产 3 Reactions of Grignard reagents 三 格氏试剂反应 o Reactions with carbonyl compounds 化合物与羰基反应 o Reactions with other electrophiles 亲电反应与其他 o Formation of bonds to B, Si, P, Sn 到B组债券，硅，磷，锡 o Carbon–carbon coupling reactions 碳碳偶联反应费尔巴哈论 o Oxidation 氧化 o Nucleophilic aliphatic substitution 脂肪族亲核取代 o Elimination 消除 广东糕点4 Grignard degradation 四 格氏退化 5 Industrial u 5 工业使用 6 See also 6 参见 7 References 7 参考资料 8 Further reading 8 进一步阅读 9 Gallery 9 画廊 |
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[ edit ] Reaction mechanism [ 编辑 ] 反应机制
The addition of the Grignard reagent to the carbonyl typically proceeds through a six-membered ring transition state. [ 5 ]此外试剂的格氏的羰基收益通常通过一个六元环过渡态。 [5]
However, with hindered Grignard reagents, the reaction may proceed by single-electron transfer.然而，随着阻碍格氏试剂，反应可进行单电子转移。
In a reaction involving Grignard reagents, it is important to ensure that no water is prent, which would otherwi cau the reagent to rapidly decompo.在格氏试剂反应有关，但重要的是要确保没有水存在，否则就会导致试剂迅速分解。 Thus, most Grignard reactions occur in solvents such as anhydrous diethyl ether or tetrahydrofuran , becau the oxygen of the solvents stabilizes the magnesium reagent.因此，大多数发生在格氏反应溶剂，如无水乙醚或四氢呋喃 ，因为这些溶剂稳定氧镁试剂。 The reagent may also react with oxygen prent in the atmosphere, inrting an oxygen atom between the carbon ba and the magnesium halide group.该试剂也可与氧气发生反应，在大气中存在，插入一之间的碳基和镁卤化物组氧原子。 Usually, this side-reaction may be limited by the volatile solvent vapors displacing air above the reaction mixture.通常，这种副作用反应可能是有限的挥发性溶剂蒸气上述反应混合物取代空气。 However, it may be preferable for such reactions to be carried out in nitrogen or argon atmospheres, especially for smaller scales.但是，它可能是最好的这种反应是进行氮气或氩气环境尺度，尤其是对于较小。
[ edit ] Preparation [ 编辑 ] 制备
Grignard reagents are formed via the action of an alkyl or aryl halide on magnesium metal .
[ 6 ] The reaction is conducted by adding the organic halide to a suspension of magnesium in an ether , which provides ligands required to stabilize the organomagnesium compound .格氏试剂通过的行动形成的烷基或芳基卤化物的镁 金属 。 [6]进行的反应是通过添加有机卤化物在暂停镁醚 ，它提供了配体所需的稳定organomagnesium化合物 。 Typical solvents are diethyl ether and tetrahydrofuran .典型的溶剂乙醚和四氢呋喃 。 Oxygen and protic solvents such as water or alcohols are not compatible with Grignard reagents.如氧气和水或醇质子溶剂与格氏试剂不兼容。 The reaction proceeds through single electron transfer . [ 7 ] [ 8 ] [ 9 ]通过该反应进行单电子转移 。 [7] [8] [9]
R−X + Mg → R−X •− + Mg •+ R - X的+镁→R - X的• - •+ +镁
R−X •− → R • + X − R - X的• - →R的•+ x的-
X − + Mg •+ → XMg • X - +镁+→XMg••
R • + XMg • → RMgX ř•+ XMg•→RMgX
