Phenols halogenophenols

The first finding was that the four p-halogenophenols (X = F, Cl, Br, or 1) have remarkably similar transition state stabilization (XTS = 0.40, 0.43, 0.46, and 0.29 mM), even though these substrates have a wide range of ability to bind to a-CD (Ks = 120, 3.6, 1.4, and 0.47 mM) (Table A4.4). This finding is inconsistent with inclusion of the phenol by the CD during the catalysed bromination and so affords yet further support for the view of the transition state implied in [9] -> [10],... 

Environmental photosensitization processes may be stimulated not only by natural but also by anthropogenic pollutants, such as phenols and dihydroxyben-zenes, which are efficient photosensitizers. Among others, phenol was found to sensitize the dehalogenation of halogenophenols [99], This behaviour shows that the simultaneous presence of adequate sensitizer and quencher in polluted environment can lead to the photosensitized decomposition of the latter and thereby to abatement of the pollution. 

In the substituted phenol/napthol group, p-phenylphenol is an extremely potent enhancer, with a reported amplification factor of 530 under experimental conditions in which 6-hydroxybenzothiazole (at double the phenol concentration) had an amplification factor of only 27 (T7) Para-substituted halogenophenols are also... 

In addition to the palladium catalysts mentioned, other transitional metal catalysts were explored and applied in this transformation as well. In 1995, Dunach and Olivero studied the nickel-catalyzed electrochemical reductive deprotection of allyl ethers. Among the various substrates, allyl-o-halogenophenols were tested as well. 2-Chlorophenol was produced from allyl-o-chlorophenol phenol was produced from allyl-o-bromophenol while 3-methyl-2,3-dihydrobenzofuran (33%) was produced from allyl-o-iodophenol together with phenol (52%). 

---