4-Nitro-phenol coefficient

It has seemed desirable to try to detect the postulated acylimidazole intermediate by spectroscopic probing. Acetylimidazole has been shown31 to have an absorbance maximum at 245 nm with an extinction coefficient of 3000. This absorbance should provide a basis for detection of the intermediate. However, in practice the strong absorbances due to the aromatic ester substrate (nitrophenyl caproate) and the product (nitro-phenol(ate)), added to the light scattering from the polymer, have made the spectrophotometric observation of the acylimidazole intermediate unfeasible under the reaction conditions previously described.26... 

These authors calculated the SC permeabihty coefficient from the differences in resistances presented by whole skin and tape-stripped (no SC) skin. The permeability coefficients in the database were taken from the SC permeabihty values reported in Table 4. SC permeabihty values were not calculated for three chemicals (2-nitro-phenol, 2,4-dimethylphenol, and 2,4,6-trichlorophenol) because the permeabihty coefficient from tape-stripped skin was not available. The permeabihty coefficient values for these three chemicals were taken from the whole skin values in Table 1. 

A subsequent study, using clearly homogeneous conditions, of the dedeutera-tion of [2-2H]-4-nitro-, -chloro-, and -methyl-phenols by aqueous sulphuric acid showed that the rate coefficients clearly increased with increasing acidity (Table 120) and plots of log rate coefficient versus the acidity function — H0 were linear,... 

Nitration of phenolic conpounds leads to the formatmi of 3-nitro Qrosme (molar extinction coefficient = 14400 at 428 nm) (Fig. 335). The leacfion is very spedfic for phenolic compounds. 

The structure-activity relationships between toxicity (log BR), monitored as cell population growth of Tetrahymena pyriformis and a number of molecular descriptors including the log 1-octanol/water partition coefficient (log Kqw). the electronic field effect (F), and the ability to donate hydrogen (Hd) have been examined for a series of para-substituted phenols. The equation log BR = 0.6849 (log Kq ) + 0.9439 (F) + 0.3373 (Hd) -1.3764, n = 29 has been found to be a good model for these derivatives and explains 91.1% of toxicity variability. Four derivatives, however, were found to lie outside the 95% confidence interval. The nitro, amino, and azophenyl derivatives were more toxic than predicted and the carboxyl derivative was less toxic than predicted. 

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