Salicylic acid synthesis

KOLBE - SCHMIDT Salicylic Acid Synthesis Caiboxylation (usually ortho) of phenols. Industrial method to obtain salicylic acid derivatives... 

KOH plants, environmental awareness in, 20 634. See also Potassium hydroxide KOH solution, 12 215 meta-Koksowy coal grade (Poland), 6 713t Kolbe-Schmidt reaction, 2 208 of salicylic acid synthesis, 22 7-8 Kolmogoroff microscale, 16 697 Konica Dry Color System, 19 348 Konjac glucomannan, 4 7241... 

The induction of salicylic acid synthesis is preceded by an increase of the temperature at the infected site. This event occurs several hours before salicylic acid is detectable [101,102]. 

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... 

Section 24 10 The Kolbe-Schmitt synthesis of salicylic acid is a vital step m the preparation of aspirin Phenols as their sodium salts undergo highly regioselective ortho carboxylation on treatment with carbon dioxide at elevated temperature and pressure... 

Kolbe-Schmitt reaction (Section 24 10) The high pressure re action of the sodium salt of a phenol with carbon dioxide to give an o hydroxybenzoic acid The Kolbe-Schmitt reac tion IS used to prepare salicylic acid in the synthesis of as pinn... 

Salicylic acid was used for phosphite protection in the synthesis of glycosyl phosphites and phosphates. This derivative is very reactive and readily forms a phosphite upon treatment with an alcohol or a phosphonic acid upon aqueous hydrolysis. ... 

Carbon dioxide reacts with phenolates 1 to yield salicylate 2 with less reactive mono-phenolates, the application of high pressure may be necessary in order to obtain high yields. This reaction, which is of importance for the large scale synthesis of salicylic acid, is called the Kolbe-Schmitt reaction ... 

The Kolbe-Schmitt reaction is limited to phenol, substituted phenols and certain heteroaromatics. The classical procedure is carried out by application of high pressure using carbon dioxide without solvent yields are often only moderate. In contrast to the minor importance on laboratory scale, the large scale process for the synthesis of salicylic acid is of great importance in the pharmaceutical industry. 

In the first total synthesis of thromboxane A2, lactone 340 is opened by potassium trimethylsilanolate 97 to give the potassium salt 341 [120]. The potassium salt of the methoxymethyl ether of salicylic acid is prepared likewise [121], as are... 

The answer is b. (Hardman, p 1061.) Sulfasalazine consists of sul-fapyridine with 5-aminosalicylic acid linked by an azo- bond. This bond is broken by bacteria that release the salicylic acid, which is believed to be the active agent. Sulfa drugs or salicylic acid used alone is not as effective. The mechanism of action is unknown, but it is believed to be protective action on the mucosa by inhibition of the synthesis of prostaglandins and leukotrienes. 

Essentially, all methods of synthesis are variations of the reaction of acetylchloride, acetic anhydride or ketene11 with salicylic acid using a variety of catalysts such as pyridine12 or sulfuric acid13 and reaction conditions (c.f. 14). The preparation of aspirin labeled with a i4c iaj-,eie(j acetyl group has also been reported.15 Efforts to improve the commercial processes continue to the present day. 

Salicylic acid has been found useful as a terminal coupling component in direct or mordant dyes to provide a bidentate site for metallisation. The free acid is also capable of complexing and ammonium chromisalicylate (5.12) is used as an intermediate in the synthesis of metal-dye complexes. Cl Mordant Orange 1 (5.3) and Yellow 5 (5.13) are examples of dyes... 

Technically important dyes are salicylic acid derivatives that function as chrome mordant dyes for wool. Thus Cl Mordant Blue 1 (6.187) is made by the aldehyde synthesis from 2,6-dichlorobenzaldehyde and 2-hydroxy-3-methylbenzoic (o-cresotinic) acid in concentrated sulphuric acid. Oxidation of the leuco base is achieved by the addition of sodium nitrite. On wool the product, which is isolated as the sodium salt, is a dull maroon colour, changing to a bright blue on treatment with a chromium salt. Some dyes of this type, such as Cl Mordant Violet 1 (6.188), also contain a basic group. This compound is also prepared by the aldehyde route. 

Carboxylation of sodium phenoxides with carbon dioxide, to give salicylic acid, the precursor to the synthesis of aspirin. 

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