Acetylsalicylate

MOT excludes the following term (retrieves dociitYients with the first lenn and not the second) (e.g., acetylsalicylic MOT synthesis) however, this often has the danger that some important documents are not found ... 

Acetylsalicylic Acid (Aspirin). C6H4[Pg.110]

It should be emphasised that salicylic acid can be readily acetylated by Method 1, and that the above preparation of acetylsalicyclic acid is given solely as an illustration of Method 2. To employ Method 1, add 10 g. of salicylic acid to 20 ml. of a mixture of equal volumes of acetic anhydride and acetic acid, and boil gently under reflux for 30 minutes. Then pour into about 200 ml. of cold water in order to precipitate the acetylsalicylic acid (11 g.) and finally recrystallise as above. Method 2, however, gives the purer product. 

Acetylsalicylic acid is largely used in medicine as an analgesic (t.e., for removing pain) and as an antipyretic (i.e., for reducing the body temperature). 

Phenols, unlike amines, cannot be acetylated satisfactorily in aqueous solution acetylation proceeds readily with acetic anhydride in the presence of a little concentrated sulphuric acid as catalyst. Salicylic acid (o-hydroxy-benzoic acid) upon acetylation yields acetylsalicylic acid or aspirin ... 

Place 10 g. of dry salicylic acid and 15 g. (14 ml.) of acetic anhydride in a small conical flask, add 5 drops of concentrated sulphuric acid, and rotate the flask in order to secure thorough mixing. Warm on a water bath to about 50-60°, stirring with the thermometer, for about 15 minutes. Allow the mixture to cool and stir occasionally. Add 150 ml. of water, stir well and filter at the pump. ReorystaUise the crude acetylsalicylic acid from a mixture of equal volumes of acetic acid and water. 

Acetylsalicylic acid decomposes when heated and does not possess a true, clearly-defined m.p. Decomposition points ranging from 128° to 135° have been recorded a value of 129-133° is obtained on an electric hot plate (Fig. II, 11, 1). Some decomposition may occur if the compound is recrystaUised from a solvent of high boiling point or if the boiling period during recrystallisation is unduly prolonged. 

The best known aryl ester is O acetylsalicylic acid better known as aspirin It is pre pared by acetylation of the phenolic hydroxyl group of salicylic acid... 

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... 

Several aspirin tablets are ground to a fine powder in a mortar and pestle. A 0.1013-g portion of the powder is placed in a 1-L volumetric flask and diluted to volume with distilled water. A portion of this solution is filtered to remove insoluble binders, and a 10.00-mL aliquot transferred to a 100-mL volumetric flask containing 2.00 ml of 4 M NaOH. After diluting to volume the fluorescence of the resulting solution is found to be 8.69. What is the %w/w acetylsalicylic acid in the aspirin tablets ... 

The preparation of an ion-selective electrode for salicylate is described. The electrode incorporates an ion-pair of crystal violet and salicylate in a PVC matrix as the ion-selective membrane. Its use for the determination of acetylsalicylic acid in aspirin tablets is described. A similar experiment is described by Creager, S. E. Lawrence, K. D. Tibbets, C. R. in An Easily Constructed Salicylate-Ion-Selective Electrode for Use in the Instructional Laboratory, /. Chem. Educ. 1995, 72, 274-276. 

This experiment focuses on developing an HPLG separation capable of distinguishing acetylsalicylic acid, paracetamol, salicylamide, caffeine, and phenacetin. A Gjg column and UV detection are used to obtain chromatograms. Solvent parameters used to optimize the separation include the pH of the buffered aqueous mobile phase, the %v/v methanol added to the aqueous mobile phase, and the use of tetrabutylammonium phosphate as an ion-pairing reagent. 

Students determine the concentrations of caffeine, acetaminophen, acetylsalicylic acid, and salicylic acid in several analgesic preparations using both CZE (70 mM borate buffer solution, UV detection at 210 nm) and HPLC (C18 column with 3% v/v acetic acid mixed with methanol as a mobile phase, UV detection at 254 nm). 

Acetylsalicylic acid [50-78-2] (i9-acetyoxyben2oic acid) was first synthesized in 1853 by reaction of acetyl chloride with sodium saUcylate. As a dmg, acetylsahcyhc acid was introduced in Germany in 1899 and into the United States in 1900. The first U.S. patent (35) for the manufacture of acetylsaUcyhc acid expired in 1917. Aspirin is a registered trademark of Bayer in many nations, but in the United States and the United Kingdom, aspirin is accepted as the generic name for acetylsahcyhc acid (36). 

Solid-phase basic dyes ai e also used for the study of their interaction with medical products nicotinic, aminocaproic, acetylsalicylic and ascorbic acids and for the establishing of the new methods of SPS determination in known medical products. 

The case of intramolecular participation in ester hydrolysis has been extensively studied using acetylsalicylic acid (aspirin) and its derivatives. The kinetic data show that the anion is hydrolyzed more rapidly than the neutral species, indicating that the carboxylate group becomes involved in the reaction in some way. Three mechanisms can be considered ... 

Detection and result The chromatogram was dried in a stream of warm air for 10 min, immersed in the reagent solution for 3 s and then subjected to intense UV radiation (high pressure lamp, A = 365 nm) for up to 10 min. Terephthalic (hRf 0 - 5), pimelic (hRf 55), suberic (hRf 60), sebacic (hRf 65 — 70) and benzoic acids (hRf 70 — 75) together with sorbic, malic, adipic, citric, tartaric, lactic and fumaric acids only exhibited a reaction on silica gel layers at higher concentrations. 4-Hydroxybenzoic, salicylic and acetylsalicylic acids fluoresced light blue after irradiation. The detection limit per chromatogram zone was 0.5 pg for salicylic acid and more than 5 pg for benzoic acid. 

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