Para group

The effects summarized in Table II show, with few exceptions, that para groups, whether activating or deactivating, exert larger effects than meta substituents. Ortho groups demonstrate both electronic and steric effects and almost without exception are deactivating. Substituents situated ortho to a reactive site are more deactivating than those which are meta or para. 

De-t-butylation of phenols t-Butyl groups are often used for protection of various positions of arenes, and are commonly removed by a reaction involving a f-butyl acceptor plus a Lewis acid. Surprisingly, A1C13 alone can effect de-f-buty-lation of phenols at room temperature in nitromethane or methylene chloride. Removal of an ort/io-f-butyl group occurs more readily than that of a para-group. 

This same DNT may be reduced by iron and aqueous hydrochloric acid to tolylene m-diamine. Ammonium monosulphide partially reduces alpha dinitrotoluene in which reduction the para group is the one concerned. Stannous chloride and alcohol exert the same action. The product in each case is C6H3 CH3 N02 NH2. 

FBS) drove further work. EC50 values for 20 in that assay were 1.3 and 1.2 pM for Bcl-2 and Bcl-xL, respectively. Further, SAR work on the terminal phenyl ring showed that nonpolar para groups promoted superior efficacy in the presence of serum [43]. Although 20 and the chloro-substituted 21 appear similar based on the data in Table 3, in the 3% serum FL5.12 assay 21 improved to 0.050 and 0.22 pM... 

The resonance of a para group can induce a charge nearer to the acidic group than the resonance of a meta group can, and the effect of the resonance of a group is greater when the group is para than... 

The effect of a para group on the strength of an acidic derivative of benzene is not restricted to its polarity and its quinoidal resonance with the ring. When two groups are para to each other and each has a quinoidal resonance with the benzene nucleus, there is an... 

The points for meta groups and those para groups that do not resonate very strongly with the benzene ring fall as close to the line... 

Figure 39 shows vfery clearly the much greater effect of a para group, whose resonance with the benzene ring induces a positive charge in the ring, on an aromatic acid in which the aromatic nucleus... 

In an ortho-substituted group, the direction of the group dipole is different from that which it would have in the meta or para group,... 

---