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Salicylic
Acid is a white crystalline powder or needle-shaped crystals with
sweetish taste; soluble in acetone, ether, alcohol, boiling water,
benzene and turpentine, sparingly soluble in chloroformbenzene, slightly
soluble in water; melts at 158°C. The sodium salt form (sodium
salicylate) is common commercially, prepared from mainly sodium phenolate
with carbon dioxide under heating and pressure. It contains both a
hydroxyl and a carboxyl group, which react with either an acid or an
alcohol. The carboxyl group forms esters with alcohols; e.g. methyl
salicylate is formed with methanol, which used in food flavorings and
preservatives; menthyl salicylate is formed with methanol, which is used
in suntan lotions. The hydroxyl group reacts with acetic acid to form
acetylsalicylic acid (called aspirin) which is the most widely common
antiseptic and antipyretic agent. Phenyl salicylate (called salol) is
formed with phenol, which is also used as an antiseptic and antipyretic
agent. The sodium salt (Sodium salicylate), a shiny white powder, is used
for antiseptics preparations and as a preservative. In addition to its
analgesic and antipyretic properties, salicylic acid possesses
keratinolytic properties and fungicidal properties. Its derivatives are used in the
treatment of hyperkeratotic, dandruff, ichthyosis and psoriasis as well
as in the treatment of fungal skin infections such as tinea.
Para-Aminosalicylic acid (abbreviated PAS and PASA) is an analogue of
para-aminobenzoic acid (abbreviated PABA) that inhibits folic acid
synthesis in Mycobacterium tuberculosis and is bacteriostatic, inhibits
growth and multiplication of the tubercle bacillus. Para-Aminosalicylic
acid and its sodium salt (sodium p-Aminosalicylate) are bacteriostatic
against mycobacteria and used in the treatment of tuberculosis;
administered orally. Brand names are Tubasal, Nemasol Sodium and etc.
Aminosalicylic acids are pharmaceutically active ingredients including
anti-infectives against colds, flu, or other virus infections. Mesalamine
(5-aminosalicylic acid, abbreviated 5-ASA) an active metabolite of
sulfasalazine, used to treat inflammation of the rectum and lower colon,
mild to moderate ulcerative colitis proctosigmoiditis, and proctitis.
Para-Aminosalicylic acid (4-hydroxybenzoic acid) is used as an
intermediate of bacteriostatic agent specially for parabens (alkyl esters
of p-hydroxy benzoic acid) which used in food and personal care products
as a preservative. It is applied in the production of liquid crystal
polymers. It is also used as an intermediate of dyes, insecticides,
pharmaceutical, pesticides and other chemical compounds. Salicylic Acid
and its derivatives are important for the preparation of other
pharmaceutical products, dyes, flavours, and preservatives.
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