The positioning effect

the effect of the original subseed on the benzene ring on the newly introduced replacement base position, called the positioning effect..the position of the newly introduced replacement base on the benzene ring is determined by the nature of the original subsoplasm base, which is divided into two categories according to their positioning effect: the first type is called neighbor and the positional positioning base. This type of replacement base on the benzene ring can make the newly introduced replacement base mainly located in its neighbor, the position (
of >60%). In addition to halogen atoms, other groups can make benzene rings active, making the replacement reaction easy to occur. The structure of these clusters is characterized by a single bond of atoms connected to the benzene ring, most of which have unac common electron pairs. These subsumeds are (ranked from strong to weak by positioning efficiency): -O - (oxygen negative ions),
-N (CH 3 ) 2(methamphetamine),
-NH2(amino),
-OH (hydroxyl), -OCH 3methoxygen),
-NHCOCH 3(acetaminophen),
-CH 3methyl), -OCOCH 3(acetyloxy),
-Cl (chlorine), -Br (bromine), I (iodine), C

6H 5(benzene base), etc. The second type is called interstational positioning base. This type of replacement base on the benzene ring can make the newly introduced replacement base mainly located in its interstit, and will make the benzene ring passivation. The structure of these clusters is characterized by the fact that atoms connected to benzene rings generally have unsaturated bonds (double or triple) or positive charges. Belongs to this type of subsolution base (by positioning efficiency from strong to weak):
-N(
CH 3 ) 3(triple methylaide positive ions),
-NO2(nitro),
-CN (cyanide), SO3 H (sulfonyl), - CHO (aldehyde-based), - COCH 3(acetaminophen),
-COOH (acetylene), - COOCH 3(methoxymethyl),
-CONH 2(aminomethyl) and so on. In addition to the positioning effect of the replacement base (which determines the action), the reaction conditions such as temperature, solvent, catalyst and the volume size of the original replacement base of benzene ring also have an effect on the ratio of reaction generation of various isomer, but generally do not change the positioning effect of the original replacement base on benzene ring. When there are already two replacement base on the benzene ring, the position of the third substitute base introduction can generally be judged according to the nature of the original two replacement base. When the positioning effects of the two subsoables are consistent, the positioning rules mentioned above are still determined. When the positioning effect of the original two subsuming base is not consistent, if the superseding base belongs to the same category, the position introduced by the third substitute base is mainly determined by the strong positioning of the replacement base. If the two subseters belong to two categories, then the third substitute base introduced position, generally by the neighbor, the position of the base to play a major role, because the neighbor, the position of the base (other than halogen atoms) can make the benzene ring alive.