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There are 2 ortho positions, 2 meta positions and 1 para position on benzene when a group is attached to it. When a group is an ortho / para director with ortho and para positions reacting with the same partial rate factor, we would expect twice as much ortho product as para product due to this statistical effect.
In organic chemistry, a directing group (DG) is a substituent on a molecule or ion that facilitates reactions by interacting with a reagent.The term is usually applied to C–H activation of hydrocarbons, where it is defined as a "coordinating moiety (an 'internal ligand'), which directs a metal catalyst into the proximity of a certain C–H bond."
In IUPAC nomenclature, an acetyl group is called an ethanoyl group. An acetyl group contains a methyl group ( −CH 3 ) that is single-bonded to a carbonyl ( C=O ), making it an acyl group . The carbonyl center of an acyl radical has one non-bonded electron with which it forms a chemical bond to the remainder (denoted with the letter R ) of the ...
Groups with unshared pairs of electrons, such as the amino group of aniline, are strongly activating (some time deactivating also in case of halides) and ortho/para-directing by resonance. Such activating groups donate those unshared electrons to the pi system, creating a negative charge on the ortho and para positions.
The ortho effect also occurs when a meta-directing group is positioned in a meta arrangement relative to an ortho–para-directing group, a new substituent introduced into the molecule tends to preferentially occupy the ortho position relative to the meta-directing group rather than the para position.
Directed metallation is not limited to lithium intermediates or even to an ortho preference. In one study [13] it is found that the reaction product of N,N-dimethylaniline with a complex of TMEDA, sodium salt of TMP and di-tert-butylzinc is a meta zincated complex as a stable crystalline compound.
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Positions on an aromatic ring relative to the R group. In chemistry, meta is a prefix, used for systematic names in IUPAC nomenclature. It has several meanings. [1] In organic chemistry, meta indicates the positions of substituents in aromatic cyclic compounds. The substituents have the 1,3-positions, for example in resorcinol.