P-Nitrosalicylic acid

Exceptions to the general pattern in Figure 6 are nitrosalicylic acids (Table 1) and the -chlorobenzoic acids. Nitrosaiicylic acid salts are more lipophilic than expected from their aqueous pKa. The o-chlorobenzoic acids are less lipophilic than a m or p-benzoic acid would be of the same pKa. The 2,6-dichlorobenzoic acid point should perhaps be on a separate line parallel to the im and p-benzoics. From the values in Table I, the following correlations can be made for predicting the pKa, and therefore log P, for similar compounds. The 95% confidence limits are indicated. 

The scope of the reaction has not yet been developed. It is known that salicylic acid, 3-, 4-, and 5-methylsalicylic acids, and p-hydroxybenzoic acid undergo the reaction, but 3,5-dibromosalicylic acid, 3-nitrosalicylic acid,... 

Nicotinic acid amide p-Substituted acetoacetanilides 5-Nitrosalicylate... 

The reaction of p-nitrophenyl 5-nitrosalicylate with ethanethiol also has a sigmoid pH-rate profile but at present it is not possible to decide whether the reaction involves intramolecular general-acid or general-base catalysis [30]. 

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