33 ‘Dihydroxy biphenyl

Chlorinated dibenzo ip-dioxins are contaminants of phenol-based pesticides and may enter the environment where they are subject to the action of sunlight. Rate measurements showed that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is more rapidly photolyzed in methanol than octachlorodi-benzo-p-dioxin. Initially TCDD yields 2,3,7-trichlorodiben-zo-p-dioxin, and subsequent reductive dechlorination is accompanied by ring fission. Pure dibenzo-p-dioxin gave polymeric material and some 2,2 -dihydroxybiphenyl on irradiation. Riboflavin-sensitized photolysis of the potential precursors of dioxins, 2,4-dichlorophenol and 2,4,5-trichloro-phenol, in water gave no detectable dioxins. The products identified were chlorinated phenoxyphenols and dihydroxy-biphenyls. In contrast, aqueous alkaline solutions of purified pentachlorophenol gave traces of octachlorodibenzo-p-dioxin on irradiation. 

Figure 13.21 Mononuclear non-haem iron enzymes from each of the five families in structures which are poised for attack by 02. (a) The extradiol-cleaving catechol dioxygenase, 2,3-dihydroxy-biphenyl 1,2-dioxygenase (b) the Rieske dioxygenase, naphthalene 1,2-dioxygenase (c) isopenicillin N-synthase (d) the ot-ketoglutarate dependent enzyme clavaminate synthase and (e) the pterin-dependent phenylalanine hydroxylase. (From Koehntop et al., 2005. With kind permission of Springer Science and Business Media.)...

Scheme 7. Synthetic avenues used for the synthesis of 4,4 -dihydroxy-biphenyl polyethers and copolyethers.

Preparation of polycyclic orthocarbonate by reaction of 2,2-dihydroxy-biphenyl with thiophosgene [187]. 

N 16.09% plts (from xylene), mp 283° when pure 285-86° sol in hot glac acet ac, xylene acet si sol in ale diffc sol in benz prepd by nitrating 2,6-dinitrodibenzofuran with nitrosyl hydrogen sulfate (Refs 2,4,6 7) 1,3,7,9-Tetranitrodibenzofurari (called 1.3.6.8-Tetranitro-diphenylenoxyd in Ger), dk-brn ndls (from acet + ale), mp 252.5° 255° prepd by heating 3,5,3, 5 l-tetranitro-2,2l -dihydroxy biphenyl with p-toluenesulfonyl-chloride dimethylaniline on a w bath (Refs 1,3,5,6 7)... 

Dihydroxy biphenyl and derivs see Biphenol and derivs 2 B122... 

Biphenol, Dihydroxy biphenyl or DiphenolfcaWeA Dioxy-diphenyl in Ger), HO.C6H4.C6H4,OH. Several derivs are described in Beil 6,989,990, 991,993(484,485) 1960,961,962] Mononitrobiphenol, 2HgN04 -not found in Beil Dinitrobiphenol, C)2HeN206- Several isomers are... 

A further modification of the PEI 82a-i consisted of the incorporation of ether groups into the aliphatic spacers [85]. Again, the PEIs 86a,b form a smectic crystalline state and a smectic A phase, but the temperature range of the smectic LC-phase is smaller than in the case of 80f-i. When hydroquinone or 2,6-hydroxynaphthalene were used as building blocks instead of 4,4 -dihydroxy-biphenyl, no LC-phases were formed at all. Hence, these results indicate that ether groups in the aliphatic spacers of PEIs destabilize the LC-phase. A further confirmation of this hypothesis will be presented below. 

The HOROH component may be bisphenol-A, bisphenol-S, dihydroxy-biphenyl, resorcinol, hydroquinone or bisphenol-A6F ... 

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.). 

FIGURE 5.38 Polycondensation of 4-fluorophenyl sulfone with 2,5-(4, 4"-dihydroxy biphenyl)-pyridine and tetramethyl biphenyl diol for the preparation of polyfaryi ether sulfone) copolymers containing 2,5-biphenylpyridine and tetramethyl biphenyl moieties. (After Pefkianakis, E. K., Deimede, V., Daletou, M. K., Gourtoupi, N., and Kallitsis, J. K. 2005. Macomol. Rapid Commun., 26, 1724. With permission.)... 

Chiral sanidic polyesters derived from copolymerizations of (S,S)-2,5-bis(2-meth-ylbutyloxy)terephthalic acid, 2,5-bis(dode-cyl)terephthalic acids, and 4,4 -dihydroxy-biphenyl have been reported [22]. These... 

An example of complex phenolics is chloro-dihydroxy biphenyl methane, dichlorophen. This is effective against SRB and slime. After a heavy shock or slug treatment if necessary, this phenolic at 5 ppm will normally maintain a system free from troublesome growth. 

Enzymatic activities A, biphenyl dioxygenase B, 2,3-dihydrodiol dehydrogenase C, 2,3-dihydroxy biphenyl dioxygenase D, meto-deavage compound hydrolase. 

Bls-(azo-2,4-dihydroxy)-biphenyl was prepared by adding bisdiazotized benzidine to resorcinol (100% excess) in a sodium acetate buffered solution. The mixture finally was made alkaline with sodium hydroxide. The product was purified by washing. 

Besides catechol, 2,2-dihydroxy biphenyl also provides a ligand which produces an effective reducing reagent (3). However, aliphatic diols such as 1,2-ethanediol and pinacol produce reducing agents which are less effective and mono-alcohols were totally ineffective to reduce ketones under the conditions. 

In a regioselective Rh-catalyzed cycloaddition, (4-methoxyphenyl)acetylene and ben-zylisocyanate react in toluene at 110°C in the presence of [Rh(C2H4)2Cl]2 and a 2,2 -dihydroxy-biphenyl-derived NMe2-substituted phosphoramidite as catalysts. After workup by chromatography, a product A is obtained in 88% yield. 

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