Ortho ring positions

We used diphenylmethanol to examine this point and found that in this compound also additivity does not hold. A definitive answer cannot therefore be given as to whether there is any hydrophobic driving force which causes Benadryl to exist in a folded conformation in aqueous solution. Moreover, with such strong interaction between the two aromatic rings, one cannot expect ir values for any substituents in the ortho ring positions to bear any relation to ir values in a simple benzene derivative. 

All the ring positions of (trifluoromethyl)benzene are deactivated compared with benzene The meta position is simply deactivated less than the ortho and para positions The partial rate factors for nitration of (trifluoromethyl)benzene are... 

Figure 12 11 compares the energy profile for nitration of benzene with those for attack at the ortho meta and para positions of (trifluoromethyl)benzene The presence of the electron withdrawing trifluoromethyl group raises the activation energy for attack at all the ring positions but the increase is least for attack at the meta position... 

Occasionally, a phenol may have more than one substituent on the ring before alkylation with aldehyde. If the groups are meta to one another and activating, they will enhance the electron density of the same ring positions and reinforce one another. If they are ortho or para to one another, they may increase or reduce reactivity, depending on the nature of the groups. The most common... 

The data in Table 4 show clearly that the reactivity of the para position is slightly higher than that of the ortho-, however, once the ortho position has been methylolated, it activates the other ring positions, particularly the remaining ortho. The details of Freeman and Lewis results have been challenged by others [80],... 

Comparison of the ortho and para indirect deactivation in 155 and 156 with that in 151 and 152 would reveal the relative effectiveness of the two effects and the influence of the ring-position. Additional examples of deactivation are ortho indirect in 2-chloro-6-methoxy-pyrazine ortho direct in 4-chloro-5-methoxypyrimidine para direct in 2-chloro-5-methoxypyrimidine ortho and para indirect in the... 

Statements in the hterature on the reactivity of the ring-positions in monocyclic azines are conflicting. Reactivity is said to be greater at the position ortho (or alpha) than at the position para (or gamma) to an azine nitrogen 2-> 4-position in pyridine and pyrimidine and 3-> 5-position in as-triazine. By others, the... 

The relation of activation by para vs. ortho ring-nitrogen in bicy-clics is altered by these special cases. For example, 4-chloroquinazoline (4-Cl-l,3-diaza) is much more reactive than the 2-chloro isomer (2-Cl-l,3-diaza) for two reasons, one being the poor activation in 2-Le-3-aza compounds. 4-Chloro-l,8-naphthyridine will be decreased in reactivity relative to its 2-chloro isomer due to the very poor activation in 4-Le-8-aza compounds and it may be only slightly more reactive than the mono-aza analog 4-chloroquinoline. The greater reactivity at the 2-position of 2,4-dichloro-l,8-naphthyri-dine 3 can be ascribed to this 4-Le-8-aza effect. ... 

While the ortho ionization data are generally fitted with notably poorer precision than for the m- and p- positions, there appear to be characteristic trends indicative of predominant contributions from polar and resonance effects. Thus, for ionization from the ring position (pyridinium ions), p yX" > whereas for ionization from the side-chain position (anilinium ions and phenols),... 

Structural identification of the N-acetylated adducts found in vivo has shown that binding to protein or GSH involves predominantly ortho-ring substitution of the arylamide with the sulfur atom in methionine or cysteine, respectively. In contrast, arylamide binding to nucleic acids vivo involves both -substitution at the C-8 position of guanine and ortho-ring substitution with the exocyclic N2 atom of guanine (26,29-31,37,38). 

Denote substituent using group name and ring position ortho (1,2), ... 

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