Mono phenols

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. 

Carbon dioxide reacts with phenolates 1 to yield salicylate 2 with less reactive mono-phenolates, the application of high pressure may be necessary in order to obtain high yields. This reaction, which is of importance for the large scale synthesis of salicylic acid, is called the Kolbe-Schmitt reaction ... 

The durability of the antioxidant can be affected by a number of factors, the most important being the amount present in the compound. The process of vulcanisation can result in the loss of migratory or volatile antioxidants. Over long periods of service, the antioxidant will decrease in concentration at ambient temperatures due to reaction with oxygen. Loss by volatility is usually only a problem with antioxidants such as the mono-phenolics. 

The mono-phenolic aporphine derivative (6aR)-( —)-l 1-hydroxyapor-phine (6aR-14) is a DA agonist. Very interestingly, its 10-methyl analogue (6aR-15) is devoid of DA effects but instead it potently binds to and stimulates central 5-HTlA receptors [67]. A ring-contracted aporphine analogue... 

Morphinandienones have also been synthesized by the oxidation of mono-phenolic benzylisoquinolines with vanadium oxyfluoride in trifluoroacetic acid, other products of the reaction being proaporphines, and similar oxidations have been accomplished with phenethylisoquinolines.183 The same reagent will oxidize the lactam (150) to the dienone (151), which is an analogue of dehydrometatheb-ainone, and the same cyclization may be effected by electrochemical oxidation.184... 

The mono-phenols are liquids or low melting-point crystalline solids, while the poly-phenols are crystalline solids only. The mono-phenols... 

MONO-PHENOLS, MONO-HYDROXY BENZENES Phenol, CeHft—OH, Hydroxy Benzene, Carbolic Acid... 

The poly-phenols or poly-hydroxy benzenes are obtained from the dry distillation products of wood. The methods of synthesis are in general those for the mono-phenols though the diazo reaction does not usually work well with amino phenols. Also some of the methods of preparation used for poly-phenols do not apply to the mono-phenols. In general properties they resemble the mono-compounds, but they are usually more easily soluble in water, react more readily and are characterized by their strong reducing properties. 

The substituted phenols result from the substitution of an additional element or group in the original benzene ring. Derivatives of only the mono-phenols will be mentioned. Considered as benzene derivatives these compounds will be poly-substitution products and, therefore, possible of existence in isomeric forms. We thus shall have ... 

We have previously stated (p. 612) that mono-phenols have the hydroxyl group replaced by the amino group when they are treated with ammonia zinc chloride. Similarly, with greater ease, the diphenols may have one hydroxyl group replaced by an amino group when heated with ammonia, thus yielding amino phenols. This method is used in preparing meta amino phenol from resorcinol, meta-di-hydroxy benzene. 

The antioxidant activities of 1,4-hydroquinones are greater than those of the mono phenols of similar structure. For example, the value of the 2,6-dimethyl derivative, XXe (1.56 X 10 M- s- ), is nearly two orders of magnitude greater than that of 2,6-dimethylphenol (Ilh, Table 1, 2.5 x 10" s ). (2) Alkyl groups increase the reac-... 

Table III lists some of the compounds which have been identified in these fractions which are mainly mono phenolic types and oxygenated heterocyclic compounds. All the chromatograms of F3 to FIO showed well resolved peaks but Fll suffered from peak broadening which is more likely due to the contamination from F12. Examples of a few chromatograms are presented in Fig. 3 and are compared with a chromatogram of the total oil from H-VI (Fig. 3a). From Fig. 3a, we could only identify a few compounds and the rest...

The electrochemical behavior of 8 and 9 was explored by cyclic voltammetry in acetonitrile (Fig. 47.6). In the absence of a base, the one-electron oxidation of 8 occurred at 0.42 V. In agreement with the behavior of the corresponding phenolic analogs, this electrochemical step featured the reversible oxidation of the ferrocene group (Fc) to ferricenium (Fc+). In the presence of an imidazole excess, two oxidation steps were observed. A nearly two-electron irreversible oxidation peak appeared, the potential of which shifted toward less positive values as the imidazole concentration increased. Another peak located at 0.52 V featured a one-electron reversible oxidation process, its potential being independent of base concentration. The cyclic voltammograms obtained with 9 under the same conditions were akin to those for 8 (Fig. 47.6b). Except for the fact that no reduction wave featuring the reduction of a transient a-cation, the behavior was extremely similar to that described above for the mono-phenol. 

Schofield AD, Barros ML, Cushion MG, Schwarz AD, Mountford P. Sodium, magnesium and zinc complexes of mono(phenolate) heteroscorpionate ligands. Dalton Trans. 2009 38 85-96. 

Scheme 8.23 DTBP-Induced oxidative coupling of a mono-phenolic derivative.

One of the most versatile enzymes in nature is tyrosinase (EC. No. 1.14.18.1). Tyrosinase was discovered by Bertnard and Bourquelot about 100 years ago. In analyzing certain varieties of mushrooms, they observed that as oxidation progressed, the mushrooms changed color and finally become dark brown or black. Subsequently studies showed that this new oxidase catalyzed the aerobic oxidation of mono-phenols, and the final product of tyrosine oxidation was melanin [1]. 

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