Trialkyl-substituted phenols

Hammett (and related sigma) relationships have been applied to aquatic reactions of several classes of aromatic contaminants. For example, alkaline hydrolysis of triaryl phosphate esters fits a Hammett relationship (Table 3) is t he sum of the substituent constants for the aromatic groups and k0 is the hydrolysis rate constant for triphenyl phosphate (0.27 M 1 s-1 t1/2 = 30 days at pH 8). Triaryl esters thus hydrolyze much more rapidly than trialkyl or dialkyl-monoaryl esters under alkaline conditions. Rates of photooxidation of deprotonated substituted phenols by singlet oxygen have been found to be correlated with Hammett a constants (Scully and Hoigne, 1987). The electronic cllects of substituents on pKa values of substituted 2-nitrophenols also fit a I lammett relationship this, of course, is not a kinetic LFER. Two compounds (4-phenyl-2-NP and 3-methyl-2-NP) did not fit the relationship and were not included in the regression. Steric effects may account for the discrepancy for the latter compound. Nitrophenols are used as intermediates in synthesis of dyes and pesticides and also used directly as herbicides and insecticides. 

TSCA, 40CFR716.120.c5 aryl phosphates-phosphate esters of pherol or of alkyl-substituted phenols. Triaryl and mixed alkyl and aryl esters are included but trialkyl esters are excluded T120-C5... 

Reactions o/In yielding nonradical products that influence markedly on the reaction inhibiting or promoting it. Thus, disproportionation of 2,4,6-trialkyl-substituted phenoxyl radicals results in end products, the appropriate methylene quinone and the initial phenolic inhibitor, e.g. ... 

Substitution reactions of B-trich1oro- X-trialkyl (or triaryl)bora2iQes and alchohols, phenols, or excess amine yield the corresponding bora2iaes (100,94). 

Preparation.- Trialkyl or triaryl phosphites and trithiophosphites (55) can be obtained in 50-90% yields from white phosphorus, carbon tetrachloride, triethylamine, and the appropriate alcohol, phenol, or thiol in a polar aprotic solvent such as dimethylformamide. A series of racemic phenylbis(dialkylamino)phosphines (56) have been prepared in a one-pot synthesis as shown the bulk of the dicyclohexyl-amino group prevents substitution of the second chlorine atom, and the products (56) are claimed to be stable to air and moisture. In a one-pot synthesis tris(diethylamino)-phosphine has been treated successively with three different alcohols to give a 89% yield of the thiophosphate (57) after oxidation with sulphur. ... 

The conversion of naphthalene to 2-naphthoic acids by irradiation with carbon dioxide and electron donors (e.g. amines or dimethoxybenzene) has been further investigated and the quantum yields of the reaction measured for different solvents and donors. Electron transfer also occurs in the photochemical phosphonation of naphthalene and phenanthrene achieved by irradiation with trialkyl-phosphites and electron acceptors such as 1,3-dicyanobenzene. The photonitration of phenol in aqueous solutions of nitrate ion has been reported and phenols have been prepared by irradiation of substituted benzenes with the aromatic N-oxide (132). ... 

The protection of polyether polyols against self-oxidation and thermo-oxidative degradation is realised by the addition, to the purified polyethers, of 2000-5000 ppm of antioxidants such as hindered phenols, substituted diphenylamines, phenothiazine, trialkyl phosphites and so on. 

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