4-terf-butylphenol

To hydrogenate an aromatic ring, it s necessary either to use a platinum catalyst with hydrogen gas at several hundred atmospheres pressure or to use a more effective catalyst such as rhodium on carbon. Under these conditions, aromatic rings are converted into cyclohexanes. For example, o-xylene yields 1,2-dimethylcvclohexane, and 4-terf-butylphenol gives 4-terf-butyl-cyclohexanol. 

Methylene-bis(4-methyl-6-terf.-butylphenol), antidegradant - non-staining. 

Amino-2,6-di-terf-butylphenol reacts normally with saiicylaldehydes to form Schiff bases, and complexes of the type [ZnL lfHL = 18) have been isolated, and shown to generate radical species on treatment with Pb02. In contrast, reaction with bis(diketonato)zinc(II) complexes leads not to the Schiff bases, but to the monoiminoquinone complexes (19).326... 

This model describes the observed behaviour when 2,2 -methylene-bis(4-methyl-6-terf-butylphenol) (ArOH in Fig. 4.7) reacts with 2,2-diphenyl-l-picrylhydrazyl (Y ), for example, in several solvents including CC14 and 1,4-dioxane [19]. 

Cterically hindered phenols are used widely today as effective non- discoloring, nonstaining antioxidants for hydrocarbon systems, particularly rubbers and plastics. These compounds may be grouped in two broad classifications—monocyclic phenols represented by a compound such as 2,6-di-fer -butyl-4-methylphenol (I) and polycyclic phenols such as 2,2 -methylenebis(4-methyl-6-terf-butylphenol) (II). (Throughout this chapter, X represents tert-butyl). 

It is also known that 2,2 -methylenebis(4-methyl-6-terf-butylphenol) II, tends to give a pink discoloration in certain latex film systems. Once again, the possibility of oxidation of this material and subsequent ionization to produce the ion VI may account for this discoloration. 

At the same time, there is little advantage in having the alkoxy group in position 4 of 2,6-di-terf-butylphenol, as shown on comparison with the compound substituted in the same position by the methyl group and with 2,6-di-tert-butylphenol itself, a compound with a free position 4 (Ari = 2.69). Different influences of the nature of the substituent in... 

Table I shows the results obtained with various bisphenols which are generally considered quite effective as thermal antioxidants. Most of these additives did not retard the discoloration of the polymer. One compound, 4,4 -methylenebis(2,6-di-terf-butylphenol), showed some promise, but it discolored the polymer initially and, therefore, cannot be considered of practical importance.

Treatment of p-terf-butylphenol with a strong acid such as H2S04 yields phenol an 2-methylpropene. Propose a mechanism. 

The structures and numbering for five types of calixarenes containing intraannular hydroxyl groups121 which figure prominently in the following sections of this review are shown in Fig. 2. The cyclic tetramer composed of p-terf-butylphenol units and methylene units, for example, is named 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-hydroxycalix[4]arene in abbreviated fashion it will be referred to as p-tert-butyl-calix[4]arene. 

The Petrolite method for calixarene synthesis also leads to dihomooxacalix[4]arenes, as represented by the p-tert-butyl compound 9. Proton-NMR spectra and TLC data indicate that the mixture obtained from p-terf-butylphenol and paraformaldehyde contains appreciable amounts of 9, but it is difficult to obtain a pure sample of 9 from this mixture 23,2, 28>. Compound 9 is much more readily accessible by the thermally-induced dehydration of the (u. v(hydroxymethyl)tetramer 46 which can be readily prepared by the convergent synthesis outlined in Scheme 5 followed by bis hydroxymethylation 62), as shown in Scheme 6. Other oxacalixarenes can also be obtained by thermally-induced dehydration. For example, 2,6-6 (hydroxymethyl)-phenols (42) yield hexahomotrioxacalix[3]arenes (43)28,62,101 > j cfroxymethyl)... 

Figure 1. Products from hydrogenation of 4-terf-butylphenol influence of polymer concentration and catalyst.

It has long been known (93) that cobalt(II) complexes of phthalocyanines interact with molecular oxygen. The water-soluble tetrasulfonato derivative of the parent phthalocyanine selectively and catalytically oxidizes 2,6-di-terf-butylphenol to the benzoquinone and the dipheno-quinone in both homogeneous solution (94) and when polymer-supported (95). The active intermediate in the catal d ic cycle is proposed to be the (as expected) mononuclear dioxygen complex of the cobalt-tetrasulfonatophthalocyanine system (92). It has been proposed that the formation of a peroxo-bridged dinuclear complex is responsible for the deactivation of the cobalt(II)-tetrasulfonatophthalocyanine system, since such a dinuclear system would be unable to further bind and activate dioxygen (96). Such deactivation results, ultimately, in loss of the catalyst and low turnover ratios. 

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