Salicylic acid acetate ester

Safflower oil. See Safflower (Carthamus tinctorius) oil Safflower oil, hybrid. See Hybrid safflower (Carthamus tinctorius) oil Safflower oil monoglyceride. See Safflower glyceride Safflower oil (unhydrogenated) Safflower seed oil. See Safflower (Carthamus tinctorius) oil Sago starch. See Starch SAIB. See Sucrose acetate isobutyrate Sal ammonia Sal ammoniac. See Ammonium chloride Salicylic acid-2-ethylhexyl ester. See 2-Ethylhexyl salicylate Salicylic acid octyl ester. See Octyl salicylate Salicylsulfonic acid. See 5-Sulfosalicylic acid Saline. See Sodium chloride Salmiac. See Ammonium chloride SALP. See Sodium aluminum phosphate acidic Sal soda. See Sodium carbonate Salt. See Sodium chloride Sal tartar. See Sodium tartrate Salt cake. See Sodium sulfate... 

Methyl, ethyl, n-propyl, isopropyl, n-hutyl, benzyl, cyclohexyl esters of formic, acetic, oxalic, succinic, tartaric, citric, benzoic, salicylic (and other substituted benzoic acids), phthalic and cinnamic acids phenyl esters of acetic, benzoic and salicylic acids. 

However, this method is appHed only when esterification cannot be effected by the usual acid—alcohol reaction because of the higher cost of the anhydrides. The production of cellulose acetate (see Fibers, cellulose esters), phenyl acetate (used in acetaminophen production), and aspirin (acetylsahcyhc acid) (see Salicylic acid) are examples of the large-scale use of acetic anhydride. The speed of acylation is greatiy increased by the use of catalysts (68) such as sulfuric acid, perchloric acid, trifluoroacetic acid, phosphoms pentoxide, 2inc chloride, ferric chloride, sodium acetate, and tertiary amines, eg, 4-dimethylaminopyridine. 

S g of ethyl glycinate hydrochloride were dissolved in 400 cc of ethanol and 33.5 g of salicylic aldehyde were added. It is refluxed for half an hour and cooled. 38 cc of triethylamlne and 25 g of Raney nickel are then added whereafter hydrogenation is carried out at room temperature and under atmospheric pressure. After hydrogen adsorption was complete, the mixture was filtered and the alcohol evaporated off. The residue was taken up with acidified water, extracted with ether to eliminate part of the by-products, consisting mainly of o-cresol, then made alkaline with ammonia and extracted with ethyl acetate. The solvent was removed in vacuo and the residue crystallized from ether/petroleum ether. 36.7 g of o-hydroxybenzyl-aminoacetlc acid ethyl ester melting at 47°C are obtained. 

Acetic anhydride is mainly used to make acetic esters and acetyl salicylic acid (aspirin). 

Conversion of Acid Anhydrides into Esters Acetic anhydride is often used to prepare acetate esters from alcohols. For example, aspirin (acetylsalicylic acid) is prepared commercially by the acetylation of o-hydroxybenzoic acid (salicylic acid) with acetic anhydride. 

Suitably substituted acetals have been shown to hydrolyse rapidly by a mechanism that involves intramolecular general acid catalysis similar to that proposed for Glu-35 in (34), The largest effects have been found for acetals with the salicylate ion as the leaving group. For example, the spontaneous hydrolysis (35) of 2-methoxymethoxybenzoic acid [73] occurs 300-fold more rapidly than the same reaction of 4-methoxymethoxybenzoic acid [74] and ca. 600-fold more rapidly than the reaction of 2-methoxymethoxybenzoic acid methyl ester [75] (Capon et al, 1969 Dunn and Bruice, 1970). The... 

The analgesic aspirin, acetylsalicylic acid, is an ester, hi this compound, the alcohol part is actually a phenol, salicylic acid. Aspirin is synthesized from salicylic acid by treatment with acetic anhydride. 

Aspirin is an ester, bnt it still contains a carboxylic acid fnnction (p/Ca 3.5). In aqueous solntion, there will thus be significant ionization. However, this ionization now provides an acid catalyst for ester hydrolysis and initiates autolysis (autohydrolysis). The hydrolysis product salicylic acid (pACa 3.0) is also acidic both aspirin and salicylic acid are aromatic acids and are rather stronger acids than aliphatic compounds such as acetic acid (pACa 4.8) (see Section 4.3.5). An aqueous solution of aspirin has a half-life of about 40 days at room temperature. In other words, after about 40 days, half of the material has been hydrolysed, and the biological activity will have deteriorated similarly. 

Acid anhydrides are between acid chlorides and carboxylic acids in reactivity, so this reaction is more effective than the reaction with a carboxylic acid but less efficient than the reaction with an acid chloride. Half of the acid anhydride goes into forming the ester, while the other half becomes a carboxylic acid. Figure 12-23 illustrates this reaction, using salicylic acid as the alcohol and acetic anhydride as the acid anhydride to form aspirin, an ester. 

Forming an ester (aspirin) by the reaction of an alcohol (salicylic acid) with an acid anhydride (acetic anhydride). 

Esters of the phenolic hydroxyl are obtained easily by the Schotten-Baumann reaction. The reaction in many cases involves an acid chloride as the acylating agent. However, acylation is achieved more commonly by reaction with an acid anhydride. The single most important commercial reaction of this type is the acetylation of salicylic acid with acetic anhydride to produce acetylsalicylic acid [50-78-2] (aspirin). 

A number of 5//-l,4-benzodioxepin-ones and -diones have been prepared (72HC(26)319, p. 339). The reaction of the sodium salt of salicylic acid with 2-chloroethanol gave (269) (75BSF(2)277) and treatment of the methyl ester of 2-acetyl-6-chloro-3,5-dimethoxyphenoxyacetic acid with 3M hydrochloric acid gave (270). The dione (271) was prepared by heating 2-carboxy-5,6-dimethoxyphenoxyacetic acid in acetic anhydride and (272) was prepared from chloroacetylsalicylic acid. 

Methylis Salicylas, Methyl Salicylate, is an ester, produced synthetically, and is the principal constituent of Oil of Gaultheria and Oil of Betula. It is soluble in all proportions in alcohol or glacial acetic acid. 

A classic example of ester hydrolysis is demonstrated with aspirin. Aspirin hydrolyzes under acidic and basic conditions to yield acetic and salicylic acid (Fig. 2) (6). Aspirin easily hydrolyzes because it is an activated ester (i.e., the leaving group, carboxylate anion, can readily stabilize the anionic charge). An additional API example that undergoes ester hydrolysis is cyclandelate (7). 

A mixture of 5-chloromethyl salicylate, 3-chloro-2-methylpropene, potassium carbonate, and acetone was heated at reflux overnight. After cooling, the mixture was extracted with diethyl ether and ethyl acetate. The organic extracts were combined, washed twice with a 10% sodium chloride solution and water, dried over sodium sulfate, and concentrated in vacuum. The resulting liquid was vacuumed distilled. The fraction collected and the desired 5-chloro-2-(2-methyl-2-propenyloxy)benzoic acid, methyl ester was obtained. 

Although carboxylic acids do occur naturally, they most often are found as their ester or amide derivatives. Acetic acid is a major industrial chemical, produced in excess of 3 billion pounds annually. Some acids, such as acetyl salicylic acid (aspirin) and ibuprofen, have found considerable use in the medical field. 

Polyanhydrides have been modified by incorporating amino acids into im-ide bonds. The imide with the terminal carboxylic acids is activated with acetic anhydride and copolymerized with sebacic acid or CCP. Poly(anhydride-imides) increase the mechanical properties of the polyanhydrides. Degradation of poly(anhydride-imide)s is similar to that of polyanhydrides (i.e., surface erosion). Two different cleavable bonds (anhydride and ester) in the polymer chains have been included in polyanhydrides. Carboxylic acid-terminated e-caprolactone oligomers or carboxylic acid-terminated monomers (e.g., salicylic acid) have been polymerized with activated monomers (e.g., SA). 

Cellulose can also be esterified by aromatic acids. However, derivatives of any importance are only the cellulose cinnamic and salicylic acid esters. A number of nitrogen-containing esters are also known, for example, cellulose dialkyl di ami noacetate, cellulose acetate-N,N-dimethylaminoacetate, and cellulose propionate-3-morpholine butyrate. Because of the presence of basic substituents these derivatives, although water insoluble, can be dissolved in acidic solutions. Such derivatives have found use as surface coatings in photographic films and in tablets for pharmaceutical purposes. 

Salbutamol is made from aspirin, itself simply the acetate ester of the natural product salicylic acid, by a series of substitution reactions. The first is a Friedel-Crafts acylation (an electrophilic substitution) in which aspirin itself is the acylating agent it is an isomerization in which the acetyl group gets transferred from O to C. Acylation occurs para to the electron-donating alkoxy substituent, and gives this ketone. 

A very important ester is formed from the reaction of salicylic acid and acetic acid ... 

Since salicylic acid has both an alcohol functional group and a carboxylic acid functional group, it can undergo two different esterification reactions depending on which functional group reacts. For example, when treated with ethanoic acid (acetic acid), salicylic acid behaves as an alcohol and the ester produced is acetylsalicylic acid (aspirin). On the other hand, when reacted with methanol, salicylic acid behaves as an acid and the ester methyl salicylate (oil of wintergreen) is produced. Methyl salicylate is also an analgesic and part of the formulation of many liniments for sore muscles. What are the structures of acetylsalicylic acid and methyl salicylate ... 

Salicylic acid resin has also been used as a polymeric support material for FeCl3 Lewis acid [24]. This catalyst had high catalytic efficiency in ester synthesis and acetalization. 

Salol and Aspirin.— The sodium salt and several derivatives possess medicinal properties as internal antiseptics as antipyretics or temperature reducers, and to lessen the pain of rheumatism. The most common of these are salol, which is the phenyl ester of salicylic acid, as an acid, and aspirin, which is the acetic acid ester of salicylic acid, as a phenol. 

Esters.— The simplest class of compounds present in essential oils are the esters or ethereal salts (p. 140). In our early discussion of these compounds in the aliphatic series it was stated that the odor and flavor of common fruits is probably due to ester compounds and that certain empirical mixtures of esters are used as artificial fruit essences. Artificial apple essence, for example, may be prepared by mixing certain proportions of ethyl nitrite, ethyl acetate and amyl valerate with chloroform, aldehyde and alcohol. An example of an essential oil which consists of a single ester is oil of wintergreen. vAdxh is the methyl ester of salicylic acid, ortho-hydroxy benzoic acid (p. 714). 

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