Phenol halogenated phenols

Aromatic hydroxyls Phenols, halogenated phenols, R(Hal) + 1200 salicylic acid (and derivatives) bcnzofuranols, chlorophenols (and metabolites), paracetamol, hesperidin, tyrosine... 

Polyesters Phenols, halogen phenols, nitrohydrocarbons, benzyl alcohol Hydrocarbons, alcohols... 

Preparation of phlorogluciaol or its monomethyl ether by reaction of a halogenated phenol with an alkaU metal hydroxide in an inert organic medium by means of a benzyne intermediate has been patented (142). For example, 4-chlororesorcinol reacts with excess potassium hydroxide under nitrogen in refluxing pseudocumene (1,2,4-trimethylbenzene) with the consequent formation of pure phlorogluciaol in 68% yield. In a version of this process, the solvent is omitted but a small amount of water is employed (143). 

Sodium A-methylanilide, xylene, HMPA, 60-120°, 70-95% yield. Methyl ethers of polyhydric phenols are cleaved to give the mono-phenol. Benzyl ethers are also cleaved. Halogenated phenols are not effectively cleaved, because of competing aromatic substitution. 

Electrolysis, Ni(II), Mg anode. DMF, it 77-99% yield. This method is not compatible with halogenated phenols, because of competing halogen cleavage. ... 

As recently as 1970, only about 30 naturally occurring organohalogen compounds were known. It was simply assumed that chloroform, halogenated phenols, chlorinated aromatic compounds called PCBs, and other such substances found in the environment were industrial pollutants. Now, only a third of a century later, the situation js quite different. More than 5000 organohalogen compounds have been found to occur naturally, and tens of thousands more surely exist. From a simple compound like chloromethane to an extremely complex one like vancomycin, a remarkably diverse range of organohalogen compounds exists in plants, bacteria, and animals. Many even have valuable physiological activity. Vancomycin, for instance, is a powerful antibiotic produced by the bacterium Amycolatopsis orientalis and used clinically to treat methicillin-resistant Staphylococcus aureus (MRSA). 

Organie ehemieal manufaeture Intermediate organic chemicals and byproducts Phenols, halogenated hydrocarbons, polymers, tars, cyanide, sulfated hydrocarbons, ammonium compounds... 

Halogenated phenols, particularly 2-bromo-, 2,4-dibromo-, and 2,4,6-tribromophenol, have been identified in automotive emissions and are the products of thermal reactions involving the dibromoethane fuel additive (Muller and Buser 1986). It could therefore no longer be assumed that such compounds are exclusively the products of biosynthesis by marine algae. 

Particnlarly extensive effort has been directed to the anaerobic dechlorination of alkenes and halogenated phenols that are discussed in Chapter 7, Part 3 and Chapter 9, Part 2. As a resnlt of this, the range of organisms that are able to carry this ont is considerable and inclndes... 

Under aerobic conditions, S -adenosyhnethionine is the methyl donor for methylation of meth-anethiol and methaneselenol (Drotar et al. 1987), and probably for the bacterial methylation of halogenated phenols and thiophenols (Neilson et al. 1988). It is also the probable methyl donor for fungal methylation of the oxyanions of As and Sb (Bentley and Chasteen 2002). 

Neilson AH, C Lindgren, P-A Hynning, M Remberger (1988) Methylation of halogenated phenols and thiophenols by cell extracts of Gram-positive and Gram-negative bacteria. Appl Environ Microbiol 54 524-530. 

Bollag J-M, S-Y Liu (1985) Copolymerization of halogenated phenols and syringic acid. Pest Biochem Physiol 23 261-272. 

Since the aerobic degradation of halogenated phenols takes place by monooxygenation and is discussed in Part 2 of this chapter, it is not discussed here except to note the production of chlorocat-echols from chlorophenols and chloroanilines. Emphasis is placed on chlorinated substrates, and reference may be made to a review (Allard and Neilson 2003) for details of their brominated and iodinated analogs. The degradation of aromatic fluorinated compounds is discussed in Part 3 of this chapter. 

Miiller et al. 2004) (Figure 9.20). In contrast, halogenated phenols with three or more snbstitnents are degraded by pathways in which the halogen is removed by various reactions before ring hssion ... 

The persistence of halogenated phenols and anilines in anaerobic environments is determined by the activity of anaerobic dehalogenating bacteria. Extensive effort has therefore been devoted to isolating the relevant organisms and an increasing number of strains have been obtained in pure culture. They display different specificities for the position of the halogen several bring about dechlorination specifically at positions ortho to the chlorine, while some of them can use the aromatic substrate as... 

E. Klarmann, V.A. Shtemov and L.W. Gates, The alkyl derivatives of halogen phenols and their bactericidal action. I. Chlorophenols. J. Am. Chem. Soc., 55 (1933) 2576-2589. 

Resin cures utilise phenol-formaldehyde resins with reactive methylene groups and a small added amount of either a chlorinated rubber, e.g., polychloroprene, or stannous chloride. If halogenated phenolic resins are used the additional source of a halogen may not be required. Resin cures give butyl compounds excellent heat stability and are used to good effect where this is required, e.g., in tyre curing bags which have to resist service at 150 °C in a steam atmosphere. 

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