Salicylic acid compound

With the important exception of acetals (and possibly certain other derivatives) of salicylic acid (compounds H. 1.6-11 see the following section), which are hydrolysed with intramolecular general acid catalysis by the carboxyl group, with EM s of the order of 104 M... 

After moistening the sample with digestion mixture (4.6), at least 2 h are needed for the nitro-salicylic acid compounds to be formed in the authors laboratory this period is often taken overnight. 

At least 2 h at 100 °C is necessary to obtain complete reduction of the nitro-salicylic acid compounds. 

After moistening the sample with the digestion mixture (4.4), at least 2 h is needed to form the nitro-salicylic acid compounds. A longer period (overnight), however, will prevent foaming later on. When heating at 180 " C, the sample will turn black and foam may be formed. If this reaches the neck of the flask, 1 or 2 drops of hydrogen peroxide (4.2) should be added. 

Choice of solvent for recrystallisation. Obtain small samples (about 0 5 g.) of the following compounds from the storeroom (i) salicylic acid, (Li) acetanilide, (iii) m-dinitrobenzene, (iv) naphthalene, and (v) p-toluene-sulphonamide. Use the following solvents distilled water, methylated spirit, rectified spirit, acetone, benzene and glacial acetic acid. 

The key compound m the synthesis of aspirin salicylic acid is prepared from phe nol by a process discovered m the nineteenth century by the German chemist Hermann Kolbe In the Kolbe synthesis also known as the Kolbe—Schmitt reaction, sodium phen oxide IS heated with carbon dioxide under pressure and the reaction mixture is subse quently acidified to yield salicylic acid... 

Many pharmaceutical compounds are weak acids or bases that can be analyzed by an aqueous or nonaqueous acid-base titration examples include salicylic acid, phenobarbital, caffeine, and sulfanilamide. Amino acids and proteins can be analyzed in glacial acetic acid, using HCIO4 as the titrant. For example, a procedure for determining the amount of nutritionally available protein has been developed that is based on an acid-base titration of lysine residues. ... 

Many pharmaceutical compounds contain chromophores that make them suitable for analysis by UV/Vis absorption. Products that have been analyzed in this fashion include antibiotics, hormones, vitamins, and analgesics. One example of the use of UV absorption is in determining the purity of aspirin tablets, for which the active ingredient is acetylsalicylic acid. Salicylic acid, which is produced by the hydrolysis of acetylsalicylic acid, is an undesirable impurity in aspirin tablets, and should not be present at more than 0.01% w/w. Samples can be screened for unacceptable levels of salicylic acid by monitoring the absorbance at a wavelength of... 

SALICYLIC ACID AND RELATED COMPOUNDS] (Vol 21) l-Acetamido-2-pyrrolidinone [7491-74-9]... 

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