2.6- Di-rert-butylphenol

One final anomaly we have already commented on the enhanced value for the effect of para-substituents on the ionization of 2,6-di-rert-butylphenol in 1 1 v/v Et0H-H20 at 25 °C (Section in.D). In this solvent phenol itself has a pA a value of 11.16, and the values for the 4-NO and 4-NO2 daivatives are 6.9 and 7.49, respectively, i.e. NO has a greater acid-strengthening effect on phenol than NO2 does, as we have already seen above for solutions in wate. HowevCT, the pK values of 2,6-di-rert-butylphenol and its 4-NO and 4-NO2 derivatives in 1 1 vAr Et0H-H20 are 14.22, 9.41 and 7.49, respectively, i.e. the acid-strengthening effects of NO and NO2 are reva-sed. The apparent a value of p-NO is now about 0.9. Presumably there is a considerable amount of quinonoid form in this system. 

TABLE 2 Charges on atoms of oxygen, carbon, lengths of communication and angles in 4-replaced 2,6-di-rert.butylphenols 2-10. 

Pinnavaia et al. also used LDH-MCPcTs)" " (M = metal ions in groups 7-10) as oxidation catalysts in the aerobic oxidation of 2,6-di-rert-butylphenol in water at 35°C (482-486), and the catalyst keeps its activity after 3200 turnovers ... 

J2 manometer measurement ti 2,6-di-rert-butylphenol added to inhibit induced... 

The nickel hydroxide electrode resembles in its applications and selectivity the chemical oxidant nickel peroxide. The nickel hydroxide electrode is, however, cheaper, easy to use and in scale-up, and produces no second streams/ waste- and by-products [196], Nickelhydroxide electrode has been applied to the oxidation of primary alcohols to acids or aldehydes, of secondary alcohols to ketones, as well as in the selective oxidation of steroid alcohols, cleavage of vicinal diols, in the oxidation of y-ketocarboxylic acids, of primary amines to nitriles, of 2,6-di-tert-butylphenol to 2,2, 6,6 -tetra-rert-butyldiphenoquinone, of 2-(benzylideneamino)-phenols to 2-phenyloxazols, of 1,1-dialkylhydrazines to tetraalkyltetrazenes. For details the reader is referred to Ref. [195]. 

Di-(rert-butyl)-4-methylphenol (see Topanol OC) 4-Hydroxymethyl-2,6-di-tert-butylphenol 2,2 -Ethylidenebis-(4,6-di-/ert-butylphenol)... 

Figure 12.7 Cliromatograms of a polycarbonate sample (a) microcolumn SEC ti ace (b) capillary GC ti ace of inti oduced fractions. SEC conditions fused-silica (30 cm X 250 mm i.d.) packed with PL-GEL (50 A pore size, 5 mm particle diameter) eluent, THE at aElow rate of 2.0ml/min injection size, 200 NL UV detection at 254 nm x represents the polymer additive fraction ti ansfeired to EC system (ca. 6 p-L). GC conditions DB-1 column (15m X 0.25 mm i.d., 0.25 pm film thickness) deactivated fused-silica uncoated inlet (5 m X 0.32 mm i.d.) temperature program, 100 °C for 8 min, rising to 350 °C at a rate of 12°C/min flame ionization detection. Peak identification is as follows 1, 2,4-rert-butylphenol 2, nonylphenol isomers 3, di(4-tert-butylphenyl) carbonate 4, Tinuvin 329 5, solvent impurity 6, Ii gaphos 168 (oxidized). Reprinted with permission from Ref. (14).

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