Carboxylation Kolbe-Schmitt

A large number of salts of sahcyhc acid have been prepared and evaluated for therapeutic or other commercial use. Table 7 hsts those most frequently referenced. Sodium sahcylate has analgesic, antiinflammatory, and antipyretic activities and was used extensively in the sixteenth and seventeenth centuries as a remedy, prepared from natural sources, for arthritis and rheumatism. In the 1990s the salt can be obtained directly from Kolbe-Schmitt carboxylation or by the reaction of sahcyhc acid with either aqueous sodium bicarbonate or sodium carbonate. The resulting mixture is heated until effervescence stops the salt is then isolated by filtration and evaporation to dryness at low temperatures. Generally, the solution must be kept slightly acidic so that a white product is obtained if the mixture is basic, a colored product results. The USP product contains 99.5—100.5% NaC H O (anhydrous). The May 1996 price was 8.15/kg (18). 

Manufacture. Several methods have been described for the preparation of -hydroxyben2oic acid. The commercial technique is similar to that of salicylic acid, ie, Kolbe-Schmitt carboxylation of phenol. The modification includes the use of potassium hydroxide in place of caustic (51). The dried potassium phenate is heated under pressure, 270 kPa (2.7 atm) or more, with dry carbon dioxide at 180—250°C. The potassium salt [16782-08-4] of Nhydroxyben2oic acid forms almost quantitatively and can be converted to free acid by using a mineral acid. 

The enzymes catalyzing the Kolbe-Schmitt carboxylation seem to occur ubiquitously. Some of them, such as 2,6-dihydroxybenzoate decarboxylase and pyrrole-2-carboxylate decarboxylase, catalyze efficiently the reverse carboxylation reaction and accumulate high concentration of 2,6-dihydroxybenzoate from 1,3-dihydroxybenzene and pyrrole-2-carboxylate from pyrrole, respectively, in the... 

The use of C02 in chemistry normally requires its interaction with metal centers of catalysts one such example is the Kolbe-Schmitt carboxylation of phenol to produce salicylic acid. The potential of C02 as a raw material in the synthesis of carboxylates, carbonates, or carbamates is rather limited. A future aim is the economically attractive synthesis of carboxylic acids, or optically... 

Recent Applications of the Kolbe-Schmitt Carboxylation Synthesis of l,3-Dialkylimidazolium-2-Carboxylates... 

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 work presented here describes initial fundamental research efforts aimed at the generation of a co-metabolic process intended to replace the Kolbe-Schmitt carboxylation of phenol. At present a prototype organism has been constructed utilizing enzymes from multiple aromatic catabolic pathways encoding for toluene and p-cresol metabolism (13,14). Recombinant P. putida EM2878 catalyzes the conversion of toluene to HBA in a single processing step. Central to the conversion... 

Higher alkylated phenols are obtained by the interaction of phenol and C16-C18 olefins from wax cracking. The corresponding alkylated salicylic acids (formed by Kolbe-Schmitt carboxylation) are lubricants for diesel engines. 

The most important derivatives of 2-naphthol are 2-hydroxy-3-naphthoic acid (BON) and its anilide, naphthol AS, which are used as coupling components in the production of azo dyes. To produce BON, 2>naphthol is first transformed into sodium 2-naphtholate with a 50% sodium hydrojdde solution. The 2-naphtholate is obtained as a fine powder. This step is followed by Kolbe-Schmitt carboxylation with CO2 at temperatures of 230 to 260 °C and a pressure of 15 bar the yield is over 90%. 

Kolbe-Schmitt carboxylation reaction a reaction that uses CO to carboxylate phenol. 

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