Halogenation

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define the condition of raw materials than regular halogen substituted Edit this section defines the hydrogen atom or a hydrocarbon group such as a hydroxyl functional group reactions. Halogenation more commonly used can be divided into three categories. Halogen-substituted organic compound in which a hydrogen atom

halogenation

① halogenated alkane reactions: alkane RH, hydrogen atoms are replaced by halogen, X2, to form a halogenated alkyl: RH + X2 ─ → RX + HX halogenated alkane ease of reaction with a halogen types of hydrocarbon and hydrogen atoms in position on, generally follow these rules: fluorine> chlorine> bromine> iodine; three hydrogen> two hydrogen> a hydrogen. Halogenated alkanes and chlorinated reaction usually refers bromination. Fluorinated reaction is too severe, the heat released is sufficient to destroy all the valence bond alkanes, difficult to control,indoor soccer shoes, is the final product of the reaction of carbon and hydrogen fluoride. On the contrary, it is difficult for iodination. Edit this paragraph reaction conditions halogenated alkane radical reactions, light, heat, or free radical initiators (such as peroxides, etc.

halogenation

) is necessary for promoting the reaction. Reaction is not easy to stop at one yuan replace the stage. For example, methane chloride product was obtained when mixtures of various chlorinated methane: Edit this paragraph strict control of raw materials than if the reaction conditions and material ratio, such as CH4: Cl2: N2 = 8:1:80 (volume ratio), 400 ~ 450 ℃, copper chloride as a catalyst, the primary was a chloromethane. Chlorinated paraffins longer carbon chain, the reaction may be substituted in the molecule on different carbon atoms, to obtain a variety of halogenated hydrocarbons, such as:

halogenated reaction

② benzene halogenation reaction: halogen substitution reaction on the benzene ring are electrophilic substitution reaction. Commonly used catalysts are iron, aluminum, phosphorus and halides: if one has been substituted on the phenyl ring,cristiano soccer shoes 2013, substituent stated location rules electrophilic substitution reaction (see electrophilic reaction). ③ halogenated aromatic heterocyclic reactions: aromatic heterocyclic ring halogenation reaction may also occur, but the reaction of difficulty vary widely. Containing aromatic heterocyclic extra π electrons, for example, thiophene, furan and pyrrole compounds, and the like, the reaction more than the benzene ring; lack of π electrons in an aromatic heterocycle, such as pyridine, etc., the reaction is much more difficult than the benzene ring, compared to the strong reaction conditions can occur:

halogenation

④ carbonyl-α hydrogen atom Halogenation: aldehydes and ketones catalyzed by a base, α hydrogen atoms on carbon halogen very easily generate a monohydric or polyhydric halides. Control halogen dosage, will enable the halogenation reaction stops at one yuan or Disubstituted stages: acid α hydrogen atoms reactive than aldehydes and ketones, normally it will take three halogenated phosphorus halide catalyzed reactions: esters, acid chlorides and anhydrides The α hydrogen atoms may be substituted by halogen, to form the corresponding halide.

halogenation

halogen, hydroxyl-substituted alcohol with hydrogen halide, the alcoholic hydroxyl group which may be substituted with halogen and generate the corresponding halide: ROH + HX ─ → RX + H2O Edit the difficulty of the law in this paragraph reaction generally follow the rules: three hydroxyl> two hydroxyl> a hydroxyl group; HI> HBr> HCl> HF. Trihalogenated phosphorus PX3 (X = Cl,Adidas Indoor Soccer Shoes, Br, I). Phosphorus pentahalide PX5 (X = Cl, Br) and

halogenation

thionyl chloride, etc. are strong halogenating reagent alcohol with these reagents can be converted to the corresponding halide. It is prepared in the laboratory on an important method of halides: 3ROH + PCl3 ─ → 3RCl + P (OH) 3 halogen replace each of these reactions is difficult for the preparation of the direct reaction of a halogenated fluoride and iodide: