Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Amidations 3-substituted halobenzenes

Nucleophilic substitution of unactivated benzene derivatives occurs by a mechanism different from the addition-elimination we saw with the nitro-substituted halobenzenes. A clue to the mechanism is provided by the reaction of p-bromotol ucnc with sodium amide. The products are a 50 50 mixture of m- andp-toluidine. [Pg.788]

The degree of rearrangement in the amination of substituted halobenzenes with alkali amides is influenced by the position of the substituent, relative to the halogen. Whereas... [Pg.458]

A number of examples of the aryne cyclization route have appeared. Treatment of the appropriately substituted halobenzene (45) with potassium amide in liquid ammonia affords 2-methylisoindole in 89% yield.74 A rationalization of the reaction is shown in Scheme 7. This route has been... [Pg.364]

Two different benzyne intermediates can be formed by reaction of meta-substituted halobenzenes, but we expect a lower activation energy (and therefore faster reaction and thus more product) for the pathway involving benzyne formation via the more stable carbanion. Therefore, if R is electron-donating, the proton para to R will be removed faster by amide ion, as shown in Figure 8.63. If R is electron-withdrawing, then the carbanion with the... [Pg.539]

Table 6 Catalytic aromatic borylation/amidation/oxidation of 3-substituted halobenzenes... Table 6 Catalytic aromatic borylation/amidation/oxidation of 3-substituted halobenzenes...
Similar substitutions are obtained with the carbanions of esters [129, 131], /V,7V-disubstituted amides [137-138] and nitriles [139-140]. The anion of cyclohexylideneacetonitrile reacts with p-bromoanisole exclusively at the y position (Scheme 26) [141]. The ambient anions of phenols and anilines react as carbon nucleophiles, as observed in the reactions of halobenzenes with 2-naphthylamine [142], 2-naphthol [143] and various phenols (Scheme 27) [144-145],... [Pg.157]

In Section 14.12, we mentioned the lack of reactivity of halobenzenes with nucleophiles. It took the activation of a nitro group on the ring for substitution to occur (see Figs. 14.94-14.96). In truth, if the nucleophile is basic enough, even chlorobenzene will react. In the very strongly basic medium potassium amide (K" " NH2) in liquid ammonia (NH3), chlorobenzene is converted into aniline (Fig. 14.111). [Pg.680]


See other pages where Amidations 3-substituted halobenzenes is mentioned: [Pg.539]    [Pg.294]    [Pg.24]    [Pg.155]   


SEARCH



Halobenzenes

Halobenzenes substitution

Substituted amides

© 2024 chempedia.info