Salicylic acid the OH group is "ortho" to the carboxyl group. It is also known as 2-hydroxybenzoic acid. It is poorly soluble in water (2 g/L at 20 °C). Aspirin (acetylsalicylic acid or ASA) can be prepared by the esterification of the phenolic hydroxyl group of salicylic acid with the acetyl group from acetic anhydride or acetyl chloride. Salicylic acid can also be prepared using the Kolbe-Schmitt reaction. Salicylic acid is used as a food preservative, a bactericidal and an antiseptic. Sodium salicylate is a useful phosphor in the vacuum ultraviolet spectral range, with nearly flat quantum efficiency for wavelengths between 10
Aminohippuric acid was given along with penicillin in order to prolong the time penicillin circulated in the blood. Because both penicillin and "para"-aminohippurate compete for the same transporter in the kidney, administering "para"-aminohippurate with penicillin decreased the clearance of penicillin from the body by the kidney, providing better antibacterial therapy. Transporters found in the kidney eliminate organic anions and cations from the blood by moving substances, in this case, drug metabolites, from blood into urine. In vultures, the NSAID diclofenac, which is extraordinarily toxic to vultures, interferes with the renal transport of uric acid via the PAH channel. p"K" = 3.83 Aminohippuric