Other phenol derivatives

The Kolbe-Schmitt reaction of potassium phenoxide with CO2 at 200 °C gives an 80% yield of p-hydroxybenzoic acid, which is used in the form of the propyl and butyl esters as a preservative in cosmetics and pharmaceuticals. 

Sodium phenoxide reacts with chloroacetic acid to yield phenoxyacetic acid, used in the production of penicillin V. 

The reaction of phenol with chloroform and alkali (dichlorocarbene) at 65 to 70 °C gives salicylaldehyde (Reimer-Tiemann synthesis), from which coumarin is produced by reaction with acetic anhydride and sodium acetate at 135 to 155 °C (Perkin reaction). Coumarin is used as a perfume and fragrance. 

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Some other phenol derivatives are somewhat local in appHcation. Eor example, aniline is produced from phenol at only two plants, one in Japan and one in the United States. Likewise, phenol is used in the production of nylon, via caprolactam (qv) or adipic acid (qv) by only one United States producer and one European producer. These markets, like the phenoHc resin and polycarbonate markets, are quite cycHcal. Thus, the entire phenol market tends to be cycHcal and closely tied to the housing and automotive markets. 

The notion of action by specific allelochemical compounds is also unjustified. Detailed study of some allelochemicals in active species has shown the presence of phenolic acid mixtures and other phenolic derivatives or terpenes. I think that we can never talk about the action of a single substance everywhere many compounds having different biological activity act simultaneously, perhaps mutually increasing their activity. As a rule, such allelochemicals are the intermediate products of soil humus, synthesis, or the ground detritus in aquatic ecosystems (11). High concentrations of these substances are lethal, moderate ones inhibit growth processes, and low concentrations stimulate them. 

Aromatic alcohols are called phenols. The simplest phenol, also called phenol, forms when a hydroxyl group replaces a hydrogen atom in the benzene ring. Phenol (carbolic acid) was used as an antiseptic in the 1800s. Today other phenol derivatives are used in antiseptic mouthwashes and in cleaning disinfectants such as Lysol. Phenols are easily oxidized, and this makes them ideal substances to use as antioxidants. By adding phenols such as BHT (butylated hydroxy toluene) and BHA (butylated hydroxy anisole) to food, the phenols oxidize rather than the food. 

Prepn of Trinitro-m-cresol other phenol derivs) 20) D.G. Harvey, JPharm ... 

Other phenol derivatives that are used to form the backbone of an epoxy resin include bisphenol E, bisphenol F, resorcinol, brominated bisphenols, and more highly functionalized molecules such as tetrakisphenylolethane. Alcohols, amines, and carboxylic acids may be combined with epichlorohydrin to give a range of diglycidyl ether based epoxy resins. Non-aromatic, commercially available epoxides are produced by peracid epoxidation of alkenes and dienes, such as vinyl cyclohexene and esters of cyclohexane carboxylic acids [23]. The chemical formulas for two common uncured polymers are shown below ... 

Although many other phenolic derivatives have been chlorinated and examined as potential haloform precursors, few have shown any particular proclivity to react in this particular fashion. Possible exceptions are a few chlorinated phenols having chlorine atoms in a meta relationship to the OH group (28 Hirose et al., 1982). The mechanistic rationales for the formation of haloforms from these compounds have not become clear. Many phenols, particularly phenolic acids, do, however, undergo other interesting and unusual chlorination reactions vide supra). 

The metabolism of other closely related coumarin derivatives has also been investigated mainly in rabbits and rats by different authors [56, 57, 59, 68]. Different amounts of metabolites with intact ring systems or of open ring and other phenolic derivatives were identified when the biotransformation of 3,4-dihydrocoumarin [69], 4-methylcoumarin [70], 3,4-dihydro-6-methylcoumarin [71], and hydroxycoumarins [48, 53] were studied in rats [72] (Table 3.2). Like the major route of 7-hydroxylation of coumarin, dicoumarol (13) and tromexan (ethyl-bis-coumacetate) are also metabolised by hydroxylation in man, mostly in the 7-position (14) of one of the coumarin rings (Figure 3.4) [73, 74]. 

Dimethylol phenol in a compound of resins based on phenol and formaldehyde. Cross reactivity is possible with other phenol derivative molecules. 

The minimum inhibition concentrations of phenol for bacteria, yeasts and fungi are significantly higher (>1000 mg/litre in nutrient agar) than those of other phenol derivatives. Moreover phenol is highly toxic. Therefore it is not important any longer as a preservative or as an active ingredient in disinfectants. 

The broad spectrum of effectiveness and the high antimicrobial activity of iso-propyl-methyl-phenols is enlightened by the MIC in Table 45. In spite of that the ispropyl-methyl-phenols have not gained much importance as preservatives for material protection or as active ingredients in disinfectants. The reason for this is the distinctive odour of these phenol derivatives, their poor water solubility and their unfavourable distribution between water and organic phases. Last but not least they are more expensive than other phenol derivatives with more favourable properties. o-Cymenol is listed in the EC list of preservatives for cosmetics with a maximum allowed concentration of 01%. 

PCMC is most effective between pH 4 and 8, where, in fact, contrary to other phenol derivatives only PCMC is sufficiently water soluble. By comparing the microbicidal concentrations of PCMC with those of PCMC-Na, solutions of which have pH values higher than 8, one notices a distinctive decrease in the activity of PCMC in alkaline media (Table 49). 

The microbicidal activity is considerably reduced in the presence of organic matter. Much more than for other phenol derivatives the efficacy of trichlorophenols depends on pH variations. 2,4,6-trichlorophenol also exhibits insecticidal effectiveness. Nowadays it is still used as an active ingredient in wood preservatives especially for the anti-sapstain treatment of freshly cut and sawn timber, moreover in preservatives for the leather industry and for functional technical fluids, e.g. protein containing formulations, concrete additives. But altogether the product as a microbicide is on the decline because of its toxicity/ecotoxicity and its intensive adherent phenolic odour. 

B. Polyphenols, hydroxycarboxylic acids, tannins and other phenol derivatives with fused rings (Table 164). 

Other phenol derivatives such as catechol (o-diphenol), hydroquinone (p-diphenol), or pyrogallol (1 3-triphenol) have also been polymerized by peroxidase in phosphate buffer giving polymeric compounds whidi are insoluUe in an aqueous HCl solution [110]. 

It is hoped that the quasi-crystalline water framework between electron donors and electron acceptors will also fixate electron transfer agents, e.g. tyrosine or other phenol derivatives. Alignment may be possible. The distant pairs of electron donors and acceptors proposed in section 6 can thus be connected and hopefully produce useful, non-covalent charge separation systems. 

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