4- Phenoxy-phenol

The reaction products from 2,4-dichlorophenol were tetrachloro-phenoxyphenols and tetrachlorodihydroxybiphenyls (Figure 5), as determined from their mass spectra and those of their methyl ethers. 4,6-Dichloro-2-(2, 4 -dichlorophenoxy)phenol (V) was the major phenoxy-phenol the mass spectral fragmentation pattern of o-hydroxyphenol ethers is quite characteristic since a hydrogen transfer occurs during the fragmentation (Figure 6). A trace of a trichlorophenoxyphenol also was detected and was formed presumably by the unsensitized reductive loss of chlorine, discussed previously. 

Detailed discussion of these findings will be presented elsewhere. Here we only wish to point out that responses to a hydrogen donor tend to be critically affected by minor structural differences between the compounds. Thus, while diphenyl ether remains substantially unaffected by the donor, its hydroxy-derivatives (phenoxy phenols) often display fairly high reactivity. Taken in conjunction with the failure of low-rank coals (7) and phenoxy phenols (10) to suffer reductive cleavage when treated with sodium in liquid ammonia, this lends some support for the existence of phenoxy phenol entities in low rank coals. 

The inertness of phenols and phenoxy phenols toward Na/liq. NH3 can be attributed to the fact that phenols are powerful proton-donors in this system, and resistance of the resultant anions toward reduction is believed to result from stabilization by resonance (10). While alkylation of low-rank coals before treatment with Na/liq. NH3 therefore offers means for establishing the presence of phenoxy phenol ethers in them, an alternative is afforded by the observation that some phenols can be reduced by concentrated solutions of lithium (11). If this latter reaction also reduces phenoxy phenols in coal, a second treatment should then cause ether-cleavage. 

We found, however, that even highly concentrated lithium (9M) or sodium (3M) solutions did not reduce coal in a manner that increased its hydroxyl content and in parallel tests, 100% unreacted p-phenoxy phenol was always recovered from the lithium solutions ... 

A + A H —> AH + A - ferf-Bu3-phenoxy + 4-MeO-phenol ferf-Bu3-phenoxy + phenol ferf-Bu3-phenoxy + 3-chloroaniline (MeO)2-diphenyl nitroxide + 2,6-tert-Bu2-phenol... 

Chlorophenols may contain a variety of by-products and contaminants such as other chlorophenols, polychlorinated phenoxy-phenols and neutral compounds like polychlorinated benzenes and diphenyl ethers, PCDDs and PCDFs (39). Some of these contaminants may also occur in chlorophenol derivatives like phenoxy acids, other pesticides and hexachlorophene. The possible presence of PCDDs and PCDFs is of special significance because of their extraordinary toxicological properties. 

White sponge, Dysidea sp. (Fig. 10.5), has been observed to overgrow members of the family Poritidae at Okinawa Island. Extracts from this sponge have been shown to contain brominated diphenyl ethers, which show potent cytotoxicity against P388 cells. Two known compounds, S -dibromo -p /l -dibromophenoxy) and 3,6-dibromo-2-(4 -dibromo-phenoxy)phenol (Fu and Schmitz, 1996 Fu et al., 1995 Fig. 10.6), were... 

Kerkvliet, N.I., Brauner, J.A. Matlock, J.P. (1985) Humoral immunotoxicity of polychlorinated diphenyl ethers, phenoxy phenols, dioxins and furans present as contaminants of technical grade pentachlorophenol. Toxicology, 36, 307-324... 

Phenoxy 4 fluoro bromo benzene silafluofen p-Phenoxy phenol diofenolan, fenoxycarb, pyriproxifen 2 Phenoxy propionic add dichlorprop... 

Most preparation methods of PBDEs reported are patents describing the bromination of diphenylether in the presence of a catalyst [1]. This results in products containing mixtures of brominated diphenylethers (Table 3). PBDEs have not been reported to occur naturally in the environment, but the related polybrominated phenoxy phenols have been found in several marine organisms, e.g. in Dysidea herbacea, Dysidea chlorea, and Phyllospongio foliascents [3]. Vionov et al. [14] showed that the bacteria Vibrio sp. associated with the sponge Dysidea sp. is capable of producing brominated diphenylethers. 

The 2,4,6-trichlorophenol thus formed produces polychloro phenoxy phenols 8 and 2 through the process described in the previous section. 

These results confirm our hypothesis, and prove the essential role of polychlorinated gem-dichlorocyclohexadienones as reaction intermediates which can react to give either noble products (chlorinated phenols in meta), or unwanted condensation products (polychloro phenoxy phenols, polychloro dihydroxy biphenyls, etc.). 

Phenol, 3-(2-chloro-4-(trifluoromethyl)phenoxy)-, acetate. 2-Chloro-1-(3-acetoxyphenoxy)-4-(trifluorDmethyl)-benzene 2-Chloro-4-trifluoromethyl-3 -acetoxy-di-phenyl ether 3-(2-Chloro-4-(trifluoromethyl)-phenoxy)-phenol acetate EINECS 256-635-0 Phenol, 3-(2-chloro-4-(trifluoromethyl)phenoxy)-, acetate... 

Figure 3. Vertically expanded NMR spectrum of the reaction mixture after addition of 25 pL of H1O2 (Insert NMR spectrum of p-phenoxy phenol).

Me ether [122738-75-4]. 2-Methoxy-4- 2-propenyl)-6-[4- 2-propenyl)phenoxy]phenol. 2-Hydroxy-3-methoxy-4, 5-di-2-propenyldiphenyl ether. 4, 5-Diallyl-2-hydroxy-3-methoxydiphenyl ether C19H20O3 M 296.365 Constit. of the bark of Magnolia henryi. Gum. 

Unfortunately, PCP often contains impurities that are toxic not only to fungi and bacteria but also to other living organisms. Its environmental impact includes effects on human health as well as on plants and other environmental organisms, such as aquatic species and wildlife. Its impurities include the less chlorinated phenols, polychlorinated phenoxy phenols, polychlorinated dibenzo-p-dioxins, and polychlorinated furans. By the late 1980s, pentachloro-phenol and its impurities had become so ubiquitous in the environment that its use has now been restricted. 

The cyclization of polychlorinated phenoxy phenols is also a bimolecular reaction which yields PCDDs under the influence of heat. 

A mixture of tetra-chloro-phenoxy phenols and tetra-chlorodihydroxy biphenyls, no polymeric products detected 2,6-dichlorophenoxyl semiquinone radical anion semiquinones rapidly disproportionate to 2,6-dichlorobenzoquinone and 2,6-dichlorohydroquinone 50% degraded in 10 days major products chloranilic acid, yellow compound (C12HO4CI7) identified as 3,4,5-trichloro-6-(2 -hydroxy-3, 4, 5, 6 -tetra chloro-... 

Chemical Properties. Lignin is subject to oxidation, reduction, discoloration, hydrolysis, and other chemical and enzymatic reactions. Many ate briefly described elsewhere (51). Key to these reactions is the ability of the phenolic hydroxyl groups of lignin to participate in the formation of reactive intermediates, eg, phenoxy radical (4), quinonemethide (5), and phenoxy anion (6) ... 

Cl Disperse Violet 26 is prepared by the reaction of l,4-diamino-2,3-dichloroanthraquinone (Cl Disperse Violet 28 (35)) with potassium phenoxide in phenol as a solvent at high temperature. Introduction of phenoxy groups into the 2,3-position shifts the shade to bright, reddish violet and improves the lightfastness and sublimation resistance. 

Finally mention may be made of the phenoxy resins. These do not contain the carbonate group but are otherwise similar in structure, and to some extent in properties, to the bis-phenol A polycarbonate. They are dealt with in detail in Chapter 21. 

The so-called phenoxy resins were a development of epoxide resin technology which had hitherto been used exclusively in the thermosetting resin field (see Chapter 26). As with the most important epoxide resins they are prepared by reacting bis-phenol A with epichlorohydrin to give the following structure (Figure 21.9) ... 

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