Aspirin mixture

TABLE 1 Apparent First-Order Decomposition Rate Constants of Aspirin and Amounts of Adsorbed Water in PCC-Aspirin Mixtures at 30, 40, and 50°C... 

FIG. 11 Relationship between the amount of adsorbed water and apparent first-order decomposition rate constants of aspirin in PCC-aspirin mixtures at various temperatures. ( ) 30°C (A) 40 C (O) 50°C. (From Ref 24.)... 

Carbon dioxide is used in the manufacture of sodium carbonate by the ammonia-soda process, urea, salicyclic acid (for aspirin), fire extinguishers and aerated water. Lesser amounts are used to transfer heat generated by an atomic reactor to water and so produce steam and electric power, whilst solid carbon dioxide is used as a refrigerant, a mixture of solid carbon dioxide and alcohol providing a good low-temperature bath (195 K) in which reactions can be carried out in the laboratory. 

Hydrolysis of Aspirin. Gently boil a mixture of i g. of aspirin and 15 ml. of 10% sodium hydroxide solution in a 50 ml. conical flask under reflux for 20 minutes. Then cool the solution thoroughly and add dilute sulphuric acid until the precipitation of the... 

Acetylation. Boil i g. of salicylic acid with 4 ml. of an acetic anhydride-acetic acid mixture (equal volumes) under reflux for 10 minutes. Pour into water. Filter off the aspirin (p. 111), wash with water and recrystallise from aqueous acetic acid (1 1) m.p. l36 ... 

The following is an alternative method of purifying the crude aspirin. Dissolve the solid in about 30 ml. of hot alcohol and pour the solution into about 75 ml. of warm water if a sohd separates at this point, warm the mixture until solution is complete and then allow the clear solution to cool slowly. Beautiful needle-like crystals will separate. The yield is 13 g. The air-dried crude product may also be recrystallised from benzene or from ether - light petroleum (b.p. 40-60°). 

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... 

The analysis of APC tablets (a mixture of aspirin, phenacetin, and caffeine) has been a common undergraduate laboratory experiment. This experiment describes modifications to the standard analysis for APC tablets in which paracetamol (also known as acetaminophen) replaces phenacetin. 

Aluminum acetylsaHcylate is a tasteless, nonbasic, stable, alternative therapeutic salt to aspirin (83). Also called aluminum aspirin, it is an insoluble white to off-white powder prepared by reaction of aluminum isopropoxide with sodium acetylsaHcylate in an organic solvent. The product precipitates from the reaction mixture (83). Standards requke that aluminum aspirin contain not less than the equivalent of 80% aspirin, corresponding to 90% purity on an anhydrous basis. The aluminum oxide assay must be 12—17% (81). 

Add 2.0 g of salicylic acid, 5.0 mL of acetic anhydride, and 5 drops of 85% H3P04 to a 50-mL Erlenmeyer flask. Heat in a water bath at 75°C for 15 minutes. Add cautiously 20 mL of water and transfer to an ice bath at 0°C. Scratch the inside of the flask with a stirring rod to initiate crystallization. Separate aspirin from the solid-liquid mixture by filtering through a Buchner funnel 10 cm in diameter. 

High performance liquid chromatography is used for the separation and quantitative analysis of a wide variety of mixtures, especially those in which the components are insufficiently volatile and/or thermally stable to be separated by gas chromatography. This is illustrated by the following method which may be used for the quantitative determination of aspirin and caffeine in the common analgesic tablets, using phenacetin as internal standard where APC tablets are available the phenacetin can also be determined by this procedure. 

Sample mixture. A suitable sample mixture is obtained by weighing out accurately about 0.601 g of aspirin, 0.076 g of phenacetin and 0.092 g of caffeine. Dissolve the mixture in 10 mL absolute ethanol, add 10 mL of 0.5M ammonium formate solution and dilute to lOOmL with de-ionised water. 

Procedure. Inject 1 fiL of the sample solution and obtain a chromatogram. Under the above conditions the compounds are separated in about 3 minutes, the elution sequence being (1) aspirin (2) phenacetin (3) caffeine. Measure peak areas with an integrator and normalise the peak area for each compound (i.e. express each peak area as a percentage of the total peak area). Compare these results with the known composition of the mixture discrepancies arise because of different detector response to the same amount of each substance. 

On rare occasions, when pain is not relieved by the narcotic analgesics alone, a mixture of an oral narcotic and other drugp may be used to obtain relief. Brampton s mixture is commonly used to identify these solutions. In addition to the narcotics, such as morphine or methadone, other dragp may be used in the solution, including antidepressants, stimulants, aspirin, acetaminophen, and tranquilizers. The pharmacist prepares the solution according to the primary health care provider s instructions. 

As the solvent mixture also contained 225 mg of tetramethyl ammonium hydroxide pentahydrate per liter at a high water content (75%), the surface of the reverse phase would have been largely covered with the tetramethyl ammonium hydroxide pentahydrate. This would have acted as an adsorbed ion exchange stationary phase. It is clear that the free acids, salicylic acid, acetylsalicylic acid (aspirin) and benzoic acid were retained largely by ionic interactions with adsorbed basic ion exchanger and partly by dispersive interactions with the exposed reversed phase. The acetaminophen and the caffeine, on the other hand, being unionized substances, were retained only by dispersive interactions with the exposed reversed phase. 

This example will illustrate the quantitative analysis of aspirin (acetylsalicylic acid), phenacetin and caffeine in a mixture. The structures of these three are shown in Fig. 4.4a. 

A commercial analgesic tablet is stated on the packet to contain 325 mg of aspirin and 50 mg of caffeine per tablet. Two tablets + 0.0773 g of phenacetin were shaken with 10 cm3 of ethanol for 10 minutes, then 10 cm3 of 0.5 mol dm 3 ammonium formate were added and the mixture made up to 100 cm3. The tablets contain insoluble excipients, so a little of the solution was filtered before chromatography --- ... 

The maximum at 277 nm has been used to determine aspirin in tablets after chromatography (see Section 5.43). It also has been used to determine aspirin in mixtures with other drugs (cf. 21). For simultaneous determination of... 

However, the driving force in this reaction is not large, so one usually ends up with an equilibrium mixture of water, salicylic acid, ASA and acetic acid. A better approach to produce ASA (aspirin) is to react acetic anhydride with salicylic acid in the presence of phosphoric or sulfuric acid acting as a catalyst ... 

LWQ is 130 mg. Therefore, weigh 130 mg of aspirin and qs with lactose to 676 mg to obtain the stock mixture. From the stock mixture, weigh out 130 mg. 

Example In an overdose case where evidence was available for the ingestion of Percodan (a mixture of several common drugs) the isobutane-CI mass spectrum of the gastric extract was obtained (Fig. 7.8). [29] All drugs give rise to an [Mh-H] ion. Due to the low exothermicity of protonation by the tert-C Hi) ion, most [Mh-H]" ions do not show fragmentation. Solely that of aspirin shows intense... 

A 1-50 g mass of aspirin was hydrolysed with 25-0 cm of 1-00 mol NaOH solution. After the hydrolysis was complete, the reaction mixture was transferred, with rinsings, to a 250 cm standard flask and made up to the graduation mark with distilled water. The solution was mixed thoroughly and 25-0 cm was pipetted Into a conical flask, along with a few drops of phenolphthalein Indicator. This was titrated with 0-0500 mol sulfuric add solution until the end-point of the titration was Indicated by the colour change from pink to colourless. The titrations were repeated until concordant results were obtained. 

In a synthesis reaction, an impure sample of aspirin was prepared from 2-hydroxybenzoic acid and ethanoic anhydride. The reaction mixture was heated for approximately 10 minutes. 

In chromatogram A, the co-spot mixture produced a single spot when developed. This shows that the product made was almost certainly aspirin. In chromatogram B, the co-spot produced two spots. This highlights that the product of the reaction was not aspirin. 

Add a small volume of hot ethanol to the aspirin and see if it dissolves. If any solid remains, add another small volume of hot ethanol. Place the aspirin-ethanol mixture on a hot-plate for one minute. If any solid remains, add another small volume of ethanol. Repeat until all the solid has dissolved. Carry out a hot filtration to remove any insoluble impurities and leave the filtrate to cool to room temperature. Filter the crystals. 

In medical practice, other salicylic acid derivatives are used in the form of salts. Magnesium salicylate and sodium salicylate are less effective than respective doses of aspirin however, they are easier on patients that are sensitive to aspirin. Choline magnesium trisalicylate represents a mixture of choline salicylate and magnesium salicylate, which has the same effect as aspirin however, it is easier on patients in which gastrointestinal effects are observed upon taking aspirin. 

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