Phenols, viii groups

Identification of phenolic hydroxyl groups. The groups which are neutralized by sodium hydroxide, but not by the carbonate, and which give acid-resistant methoxy groups, seem to be phenols. This was confirmed (35, 46) by the reaction with typical phenol reagents, dinitrofluoro-benzene, and p-nitrobenzoylchloride (Table VIII). 

A recent improvement involves the rearrangement in the presence of bis(trimethylsilyl)-urea to protect intermediately the phenolic hydroxy groups formed during the rearrangement. Thus, the / -allylcalix[4]arene was obtained in 99% yield and the larger p-allylcalix[4]arenes also became available . Multiple tandem rearrangements have also been used to convert O-linked double calixarenes into p-linked double calixarenes (see Section VIII. A). 

It is evident from Table VIII that substrate molecules with protonated phenolic hydroxyl groups (at pH 3.5) react by about 2 orders of magnitude faster with the a-cyclodextrin molecule than the corresponding molecules in anionic form (at pH 11.0). 

B) Phenols of this group slowly react with hydroperoxide and dioxygen. Respective phenoxyl radicals are relatively unreactive toward RH and ROOH, but can react with R02 giving rise to peroxides and then to free radicals. For these phenols, appropriate inhibitory mechanisms are I III and VI VIII. 

A nitro group at the meta position is readily hydrolysed in water to the phenolic group with the formation of the nitro derivative of N-methyl-m-aminophenol (VIII). Since technical dimethylaniline usually contains a certain amount of methylaniline,... 

Owing to the presence of the phenolic group, the substance (VIII) forms explosive salts. Its lead salt, however, is of no practical value owing to its hygroscopicity. 

Amine and Aminophenol Derivatives. Amines and aminophenols (Table VIII) react with the F-C reagent about as predicted considering the aromatic amino groups equivalent to phenolic hydroxyls. This would be an important interference with total phenol assay in samples with appreciable aromatic amine content. Fortunately, for this and other reasons as well, the major wine grapes and most other fruit and vegetable products are free of significant concentrations of aromatic amines which would interfere. Correction might be made for methyl anthranilate... 

Naphthalene- and anthracene-derived phenols did, however, almost uniformly precipitate (Table VI). In natural materials (not grapes or wines) which contain them they would be included in the formaldehyde precipitable group. Several primary amines capable of SchifFs base formation reacted with formaldehyde to lose their F-C oxidizability, but only the resorcinol analog, 3-aminophenol, precipitated (Table VIII). Sulfite also reacted but did not precipitate with formaldehyde, and the F-C oxidizability was suppressed (Table IX). The resorcinol derivative, 2,4-dimethoxycinnamic acid, formed a precipitate with formaldehyde, but it did not react appreciably in the F-C assay. 

These complexes can exist in a triangular peroxo form (7a) for early d° transition metals, or in a bridged (7b) or linear (7c) form for Group VIII metals. They can be obtained from the reaction of alkyl hydroperoxides with transition metal complexes (equations 9 and 10),42-46 from the insertion of 02 into a cobalt-carbon bond (equation ll),43 from the alkylation of a platinum-peroxo complex (equation 12),44 or from the reaction of a cobalt-superoxo complex with a substituted phenol (equation 13).45 Some well-characterized alkylperoxo complexes are shown (22-24). 

Resorcinol Resins. The reactivity of phenol with formaldehyde is greatly increased with two hydroxyl groups on its nucleus (resorcinol VIII). Room temperature polymerization is observed without the need for any catalyst. The rate of reaction goes through a minimum at a pH of 3.5 and increases at lower or higher pH values. To make a useful adhesive, prepolymers, similar to novolaks, are pre-... 

When the chlorine of a-chlorocodide [lxix, R = Cl] is replaced by groups other than hydroxyl, the new substituent appears at C-8 (see Chap. VIII) and ethers of -codeine can be prepared by heating a-chlorocodide with alcohols or with the sodium salts of.phenols [353, 403, 418-20]. -codeine methyl ether methiodide can also be prepared by direct methylation of -codeine [411]. 

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