Phenolcarboxylic acids Phenols

Phenylpropane amino acids Cinnamic acid, coumarins, lignin, lignans, flavan derivatives, stilbenes, phenolcarboxylic acids, phenols, components of volatile oils. 

Phenolat, n. phenoxide, phenolate. Phenol-ather, m. phenol ether, -carbonsaure, /. phenolcarboxylic acid, -gruppe, /, phenol group,... 

Salicylic acid is manufactured on a large scale. In the dye industry it serves for the production of valuable azo-dyes which exhibit great fastness. To some extent these dyes are applied to mordanted fibres. In addition, the acid and its derivatives are widely used in pharmacy. Being a phenolcarboxylic acid it has a powerful disinfecting action (preservative). It has further proved itself an important antirheumatic and an analgetic. The derivative in which the phenolic hydroxyl group is acetylated (aspirin) has become especially popular. The first medicament of the series was the phenyl ester of salicylic acid, salol, which is produced as a by-product in the technical process. The preparation of salicylaldehyde has been described above (p. 235). 

Color test. Some phenols give characteristic colors on addition of a drop of ferric chloride solution to a dilute aqueous or alcoholic solution of the material. The test is negative with nitrophenols and with m- and p-phenolcarboxylic acids. The j8-keto ester (1) and the j8-diketone (2) give ferric chloride color tests indicative of the presence of the enol forms. 

Potassium carbonate Kolbe synthesis of phenolcarboxylic acids from phenols KaCO,... 

Since the lower phenols are volatile, they are best separated after conversion into involatile, coloured derivatives (azo dyes) (see p. 664) [37, 87, 154]. The TLC of the azo compounds derived from other simple alkyl phenols also has been described in these articles [37, 87]. Eaesel-guhr layers, impregnated with formamide, have been used as well as strongly alkaline silica gel layers. After separation, the coloured derivatives can be quantitatively eluted from the layer and determined [154]. Mixtures of alcohols and phenols can be satisfactorily chromatographed as their dinitrobenzoates [38]. Numerous phenolcarboxylic acids have been separated on mixed layers of silica gel G and cellulose, using the solvents toluene-ethyl formate-formic acid (50 + 40 + 10) and chloroform-acetic acid-water (80 + 20 + 20). Phenolcarboxylic acids differing little in polarity, can be better separated if the layers are saturated with moisture before use [158]. 

Table 164. Group B, substances of medium polarity Phenols, phenolcarboxylic acids, hydroxycoumarins, flavone aglycones. Comparison of the h /-values obtained under standard conditions on ceUulose, silica gel and...

V Toluene-ethyl formate-formic acid (50 + 40 + 10) B Phenols, flavone aglycones, phenolcarboxylic acids, hydroxycoumarins [203]... 

Fuzikawa, H. (1939). The antiseptic action of phenols, phenolcarboxylic acids and the esters of lichen substances. VI. The antiseptic action of orcinol-carboxylic ester on soy cauce. J. Pharm. Soc. Jap. 59, 615-616. 

Diphenols, phenolcarboxylic acids and phenol sulphonic acids are in Table 8.6. Aminophenols and the hydroxy-derivatives of heterocyclic bases are in Table 8.11. 

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