3- acetyl-4-hydroxybenzoic acid

In addition, Pfister and coworkers investigated 3-hydroxyflavone-6-carboxylic acids as histamine induced gastric secretion inhibitors. After condensing 3-acetyl-4-hydroxybenzoic acid (45) with a variety of aldehydes 46 to deliver the chalcones 47, these purified chalcones were then subjected to the standard AFO conditions to afford flavonols 48 in 51-80% yield. Subsequent alkylation of 48 with methyl iodide or isopropyl iodide followed by saponification of the corresponding esters gave the target compounds. 

Also obtained by reaction of dimethyl sulfate with 3-acetyl-4-hydroxybenzoic acid [3941]. 

Acetyl-4-hydroxybenzoic acid, 1129 5-Acetyl-2-hydroxybenzoic acid, 1129... 

Dissolve 10 g. of salicylic acid (o-hydroxybenzoic acid) in 7 ml. of dry pyridine contained in a too ml. conical flask. Then without delay (since this solution if allowed to stand tends to become a semi-solid mass) run in 7 5 ml. (8 3 g.) of acetyl chloride, adding about i ml. of the chloride at a time, and shaking the mixture continuously during the addition. The heat of the reaction causes the temperature of the mixture to rise rapidly ... 

First,/)-hydroxybenzoic acid (HBA) and 6-hydroxy-2-naphthoic acid (HNA) are acetylated to produce the low melting acetate esters which are molten at 200°C. In an inert gas, the two monomers are melted together at 200°C. The temperature is raised to 250—280°C and acetic acid is coUected for 0.5 to 3 h. The temperature is raised to 280—340°C and additional acetic acid is removed in vacuum for a period of 10 to 60 min. The opalescent polymer melt produced is extmded through a spinning jet, foUowed by melt drawdown. The use of the paraUel offset monomer, acetylated HNA, results in the formation of a series of random copolyesters of different compositions, many of which faU within the commercially acceptable melting range of... 

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. 

Carbonation Kolbe reaction Treatment of a salt of a phenol with CO2 replaces a ring hydrogen with a carboxyl group. This reaction is applied in the conversion of phenol itself into ort/io-hydroxybenzoic acid, known as salicylic acid. Acetylation of salicylic acid produces acetylsalicylic acid (aspirin), which is the most popular painkiller in use today. 

The acetyl 1CH3C - J derivative of o-hydroxybenzoic acid is the active ingredient in aspirin... 

After oral administration of caffeic acid to rats, small amounts of vanillic acid and vanilloylglycine are excreted. The conversion of p-hydroxycinnamic acid into /7-hydroxybenzoic acid is found in rat liver mitochondria [18], Studies with /7-hydroxy[U-14C]cinnamic acid have showed that 14C02 is released during reaction, indicating that reaction probably followed the p-oxidation type reactions, the two carbon being first removed as acetyl-CoA, and then oxidized to C02. It is assumed that conversion of ferulic acid formed by methylation of caffeic acid into vanillic acid occurs in rat liver mitochondria. 

The acidity of substituted benzoic acids is dependent on the relative ability of the substituent to donate or withdraw electron density. The more strongly a group withdraws electrons, the greater is the acidity. Thus the order of increasing acid strength is 4-hydroxybenzoic acid < benzene-1,4-dicarboxylic acid < 4-acetyl-benzoic acid < 4-cyanobenzoic acid... 

The first step in the industrial synthesis of aspirin is known as the Kolbe-Schmitt carboxylation reaction. The phenolate ion reacts with carbon dioxide under pressure to form o-hydroxybenzoic acid, also known as salicylic acid. Acetylation of salicylic acid with acetic acid forms acetylsalicylic acid (aspirin). 

The reaction of acetic anhydride with salicylic acid (o-hydroxybenzoic acid) is used to synthesize aspirin. In this reaction, the phenolic hydroxyl group is acetylated (converted to its acetate ester). 

A fifth factor is certainly ease of preparation and in this characteristic the melt prepared thermotropic polymers are particularly favored. All of the polymers described thus far may be made in a conventional melt acidolysis process starting with the acetoxy derivatives of the hydroxyl containing monomers used. A typical polymerization scheme is shown in Figure 8, the preparation of the two component polyester derived from the acetylated hydroxybenzoic and hydroxynaphthoic acids. The polymerization may be carried out with or without added catalysts. The poly(ester-amides) commented on here, and the more recently reported aromatic, thermotropic poly(ester-carbonates) and poly(ester-imides), may all be synthesized in a similar manner. 

In addition to fagarine and dictamnine this plant (see Volume III, p. 70) has given aegelenine, C14H10O2N2 (mp 250°) acetyl (mp 153°) picrate (mp 246°) methiodide (mp 266°). There are no methoxyl, methylenedioxy, or A-methyl groups and fusion with alkali generates diphenylamine and p-hydroxybenzoic acid (3). 

Also obtained by reaction of acetyl chloride with 2-hydroxybenzoic acid in the presence of ferric chloride at 110-115° [4100]. 

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