Other phenols

4 Other Phenols.- 4-Hydroxybenzyl alcohol, although known as a plant metabolite has only Just been reported from a bacterial 

Though the activities for the D- and L-forms were approximately equal in the crude particulate fraction, the proportions ranged from 1 1 to 1 3 in the supernatant. 

N-( Y -L-glutamyl)-4-hydroxyanilLne (6) is produced by the mushroom Agaric us bisporus, and the 4-hydroxy aniline fragment is derived from shikimate. Feeding experiments followed by 

4-dihydroxyaniline derivative is also produced from feedings of C-labelled shikimic acid. 

The cresols occur in cresylic acid, a mixture of the three cresols together with some xylenols and neutral oils, obtained from coal tar distillates. Only the /n-cresol has the three reactive positions necessary to give cross-linked resins and so this is normally the desired material. The o-isomer is easily removed by distillation but separation of the close-boiling m- and p-isomers is difficult and so mixtures of these two isomers are used in practice. 

Other higher boiling phenolic bodies obtainable from coal tar distillates are sometimes used in the manufacture of oil-soluble resins. Mention may also be made of cashew nut shell liquid which contains phenolic bodies and which is used in certain specialised applications. 

A few synthetic substituted phenols are also used in the manufacture of oil-soluble resins. They include p-tert-butylphenol, p-tert-amylphenol, p-tert-octylphenol, p-phenylphenol and dihydroxyphenylpropane (bis-phenol A). 

---

Although phenol gives these marked colour changes, the test is unsatisfactory with many other phenols, the precise tint obtained varying with the purity of the phenol, amount of reagents used, and temperature and time of heating. 

One of the problems with all the current phenol conversions is that a certain amount of other phenols, such as resorcinol and hydro-quinone, will be formed along with the catechol (don t ask). These species are very hard to separate from the catechol because they are all so similar. Aside of carefully monitored fractional distillation there are some vague strategies which can be found in the Chemical Abstract references 116-118. 

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. 

Other Phenolic Compounds. There are several phenolic acids important to tea chemistry. GaUic acid (3) and its quinic acid ester, theogallin (4), have been identified in tea (17,18) and have been detected by hplc (19,20). 

Lysol consists of a mixture of the three cresol isomers solubilized using a soap prepared from linseed oil and potassium hydroxide, to form a clear solution on dilution. Most vegetative pathogens, including mycobacteria, are killed in 15 minutes by 0.3—0.6% lysol. Lysol has a phenol coefficient of 2. Bacterial spores are very resistant. Lysol is also the name of a proprietary product, the formula of which has changed over the years other phenols have been substituted for the cresols. 

This method has been used for the preparation of other phenolic ketones such as resacetophenone, 2-acetyl-i-naphthol,i 2-phenylacetyl-i-naphthol and 2-phenylpropionyl-i-naphthol. ... 

A number of other phenols obtained from coal tar distillates are used in the manufacture of phenolic resins. Of these the cresols are the most important... 

While phenol is the most common monomer for novolac manufacture, it is far more common to see incorporation of other phenolic materials with novolacs than with resoles. Cresols, xylenols, resorcinol, catechols, bisphenols, and a variety of phenols with longer alkyl side chains are often used. While most resoles are made with a single phenolic monomer, two or more phenolic materials are often seen in novolac formulae. These additional monomers may be needed to impart special flow characteristics under heat, change a glass transition temperature, modify cure speed, or to adjust solubility in the application process among others. 

The naphthols differ from the phenols of the henzene senes in foiming ethers after the manner of aliphatic alcohols, viz, by the action of sulphuric acid on a mixture of the naphthol and the alcohol, which the other phenols do not,... 

As is true in the case of other phenolic lipids, urushiol is also a mixture of components varying mostly in the degree of unsaturation. Thus, the urushiol from Rhus vernicefera has structures shown in Fig. 6 [139]. Rhus toxicodendron is also known to give urushiol, but its... 

Notes. (1) Other phenols which undergo this type of reaction include 4-chlorophenol, m-cresol (3-methylphenol) and 2-naphthol. 

Various phenolic acids have been reported to inhibit IAA oxidase (9, 52,120), and other phenols may act as cofactors of IAA oxidase (144). In general, the cofactors of IAA oxidase are monophenols, whereas the inhibitors of the system are polyphenols, with o-dihy-droxyphenols being the most inhibitory (52, 65). Unsaturated lactones have also been reported to inhibit IAA oxidase (2, 52). 

Williams, C. A. and Garnock-Jones, P. J. 1986. Leaf flavonoids and other phenolic glycosides and the taxonomy and phytogeny of Fuchsia sect. Skinnera (Onagraceae). Phytochemistry 25 2547-2549. 

Therefore depending upon the conditions used to simulate either in vitro or in vivo oxidation, catechins or other phenolic compounds display differences in their antioxidant properties. Catechins also limited the consumption of a-tocopherol, allowing it to act as a scavenger within cell membranes whilst the catechins scavenged aqueous peroxyl radicals near the membrane surface (Pietta and Simonetti, 1998). 

Evaporation is the oldest process for the concentration of liquid foods. Temperatures are higher compared to those of the more modern membrane filtration or freeze concentration processes. Tocopherols, carotenes, ascorbic acid, flavonoids and other phenolic antioxidants are partially destroyed by heating. Therefore, it is necessary to minimise the time needed for evaporation, and heating to the evaporation temperature should be carried out very rapidly. The temperature may be decreased if the pressure is reduced. The process is then more expensive, but losses of antioxidants become substantially lower. 

The total anthocyanin content can often be determined in crude extracts containing other phenolic materials by measuring absorptivity of the solution at a single wavelength (Table 6.3.1). This is possible because anthocyanins have typical absorption bands in the 490 to 550 nm region of the visible spectra — far from the absorption bands of other phenolics with spectral maxima in the UV range. ... 

ESI-MS has emerged as a powerful technique for the characterization of biomolecules, and is the most versatile ionization technique in existence today. This highly sensitive and soft ionization technique allows mass spectrometric analysis of thermolabile, non-volatile, and polar compounds and produces intact ions from large and complex species in solution. In addition, it has the ability to introduce liquid samples to a mass detector with minimum manipulation. Volatile acids (such as formic acid and acetic acid) are often added to the mobile phase as well to protonate anthocyanins. A chromatogram with only the base peak for every mass spectrum provides more readily interpretable data because of fewer interference peaks. Cleaner mass spectra are achieved if anthocyanins are isolated from other phenolics by the use of C18 solid phase purification. - ... 

Flavonoids and other phenolic compounds released by plant roots have important functions in plant-pathogenic interactions, feeding deterrence, nematode resistance, and allelopathic interactions they also serve as signal molecules for the establishment of symbiotic associations (72,149). However, a detailed analysis of signaling pathways involved in these interactions is currently available in only a limited number of cases (see also Chap. 7). 

It remains to be determined if one or both of these hypotheses are correct for plant roots. One feature of the inhibition of absorption by salicylic acid (and probably other phenolic acids) that may be relevant to this point is whether the neutral acid or the anion is responsible for the inhibition. In oat roots, the amount of neutral acid present when salicylic acid caused 50% Inhibition of K+ absorption was constant regardless of pH (Figure 6). However, the concentration of anion present changed several orders of magnitude. This result suggests the neutral acid is the species... 

It seems most likely that the presence of the styrene compound was at least partially responsible for the inhibition of prickly sida germination and root length, since ferulic acid alone (prickly sida seed without carpels plus ferulic acid) had no effect on prickly sida germination or root length (Table XI). The decarboxylation of phenolic acids to corresponding styrenes is known from studies on fungi and bacteria (60, 61). However, in a number of studies directly concerned with the microbial decomposition of ferulic acid, as well as other phenolic acids, no mention is made of any styrene compounds produced as a result of phenolic acid decarboxylation (62, 63, 64, 65). 

Extraction - ethanol Cyperus esculentus, tubers and leaves Ferulic acid and other phenolics 63, 64... 

Paspalum plicatulum, dried leaves Ferulic acid, other phenolics 74... 

The different classes of compounds that have been successfully separated by MEKC include, among others, phenols [932,933], antioxidants [930,934], vitamins [935], phthalate esters [931,936] (Figure 4.26) and charged and neutral dyestuffs, including some dispersive dyes [937-939]. The separation of various priority... 

---