Alicylic acid

Amino salicylic acid and its salts have been used in the treatment of tuberculosis. />-Amino s alicylic acid can be prepared by the carboxylation of, w-amino phenol (32). Aminosalicylic acid USP assays not less than 98.5% and not more than 100.5%, calculated on the anhydrous basis. The antitubercular agents are likely to be used as the more tolerated salts calcium [133-15-3], potassium [133-09-5], sodium [133-10-8], and the ethyl [6069-17-2] and phenyl [133-11-9] esters of aminosalicylic acid. 

Disodium-l,2-dihydroxybenzene-3,5-disulfonate (tiron) yields a strong yellow color when reacted with titanium salts in the pH range of 4.3-9.6 [15]. Titanium salts also react with 5- ilf< alicylic acid at pH 3-5 to yield yellow solutions [16]. Other reagents which have found limited use in identification testing are thymol [17], gallic acid [18], and salicylic acid [19]. 

Salicylic acids Cu(llXsalicylate)2 Cu( 11 X4-aminosalicylate)2 Cu( 11 X4-tertiarybutylsalicy late)2 Cu(llX4-nitrosalicylate)2 Cu(IIX3,5-diisopropyls alicylate)2... 

An excess of crotonaldehyde or aliphatic, alicylic, and aromatic hydrocarbons and their derivatives is used as a solvent to produce compounds of molecular weights of 1000—5000 (25—28). After removal of unreacted components and solvent, the adduct referred to as polyester is decomposed in acidic media or by pyrolysis (29—36). Proper operation of acidic decomposition can give high yields of pure /rhexadienoic acid, whereas the pyrolysis gives a mixture of isomers that must be converted to the pure trans,trans form. The thermal decomposition is carried out in the presence of alkali or amine catalysts. A simultaneous codistillation of the sorbic acid as it forms and the component used as the solvent can simplify the process scheme. The catalyst remains in the reaction batch. Suitable solvents and entraining agents include most inert liquids that boil at 200—300°C, eg, aliphatic hydrocarbons. When the polyester is split thermally at 170—180°C and the sorbic acid is distilled direcdy with the solvent, production and purification can be combined in a single step. The solvent can be reused after removal of the sorbic acid (34). The isomeric mixture can be converted to the thermodynamically more stable trans,trans form in the presence of iodine, alkali, or sulfuric or hydrochloric acid (37,38). 

Linear free-energy relationships in the chromic acid oxidation of alicylic alcohols have been subjected to a detailed scrutiny using pairs of epimers, including a variety of alkylcyclohexanols and some pentanols. The correlation proposed by Sicher (1962) required modification thus = O.S RT ln kjkj), where and... 

Most naturally occurring lipids are not chiral (parafiins, oleic acid, palmitin, etc.) or are mixtures of compounds which are difficult to separate (lecithin, asymmetric glycerols). A few chiral fatty acids have been used, like methylated (Figure 4.4) [8] and alicylic (Figure 4.5) [9] adds. The chiral centers of fatty acids are often comformational flexible and they are not connected with large dipole moments. Also, the chemical modification of the chiral centers is more difficult than for amino acids and sugars. Thus, chiral lipids have only limited use in liquid crystal research. 

---