Phthalic Acids and Derivatives

Toluic Acids, Xyloic Acids, Mesitylene Carboxylic Acid 

Mono-basic ring carboxy acids of the benzene homologues need only to be mentioned. 

Mesitylene yields mesitylene carboxylic acid, C6H2  

The only other ring carboxy acids to be considered in detail are the three phthalic acids. They all have the constitution of di-carboxy benzene, CeH4 = (COOH)2, and therefore three isomers are possible, orthoj meta and para. 

Relation to Xylene.—Just as toluene, mono-methyl benzene, on 

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P262-R to P265-R under "Phthalic Acid and Derivatives , and P214-R under Terephthalic-diperoxy Acid ... 

Towae,FK, Enke,W,J, Jackh,R, Bhargava,N. 1992. Phthalic acid and derivatives. In Elvers B, Hawkins S, Schultz G, eds. Ullmann s encyclopedia of industrial chemistry. 5 ed.. Volume A20. Weinheim, Germany VCH Verlagsgesellschaft, 439-457. 

PM. Lorz, F.K. Towae, W. Enke, R. Jackh and N. Bhargawa, Phthalic Acid and Derivatives in UUmann s Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, Germany, 2000. 

Important derivatives are obtaiaed from PMBs by oxidation (see Phthalic acid and otherbenzenecarboxylic acids). For example, hemimellitene is oxidized to hemimellitic acid dihydrate [36362-97-7] or hemimellitic acid [569-51-7] which can be dehydrated to hemimellitic anhydride [3786-39-8]. 

The diacids are characterized by two carboxyHc acid groups attached to a linear or branched hydrocarbon chain. AUphatic, linear dicarboxyhc acids of the general formula HOOC(CH2) COOH, and branched dicarboxyhc acids are the subject of this article. The more common aUphatic diacids (oxaUc, malonic, succinic, and adipic) as weU as the common unsaturated diacids (maleic acid, fumaric acid), the dimer acids (qv), and the aromatic diacids (phthaUc acids) are not discussed here (see Adipic acid Maleic anhydride, maleic acid, and fumaric acid Malonic acid and derivatives Oxalic acid Phthalic acid and OTHERBENZENE-POLYCARBOXYLIC ACIDS SucciNic ACID AND SUCCINIC ANHYDRIDE). The bihinctionahty of the diacids makes them versatile materials, ideally suited for a variety of condensation polymerization reactions. Several diacids are commercially important chemicals that are produced in multimillion kg quantities and find appHcation in a myriad of uses. 

Carboxyphenyl-(2-methyl-3-indoleninjdidene)methanol (303) was said to be formed by the action of phthalic anhydride on 2-methyl-indole magnesium bromide. Skatole magnesium bromide, on the other hand, apparently gave 2-carboxyphenyl-(3-methyl-2-indole-ninylidene)methanol (304) and 3-hydroxy-3-(3-methyl-l-indolyl)-phthalide (305) on treatment with 1 mole of phthalic anhydride. The derivative 305 was easily hydrolyzed in alkali, giving skatole and phthalic acid, and was thus formulated as a 1-skatolyl derivative. ... 

Besides the technical method starting from naphthalene, phthalic acid and its substituted derivatives can be prepared by oxidation of o-xylene to phthalic acid with potassium permanganate. This compound can be subsequently transformed via an anhydride, imide, and amide to a derivative of phthalonitrile, which is the more convenient starting material for several coordination compounds. The synthesis of the ferf-butyl-substituted dicarbonitrile, which is a very common starting material for highly soluble phthalocyanines, is shown below.97,105... 

For the cydative cleavage step, it turned out that aprotic conditions were definitely superior to the use of protic media. Thus, employing N,N-dimethylformamide as solvent at somewhat elevated temperatures furnished the desired compounds in high yields and excellent purities. Having established the optimized conditions, various phthalic acids and amines were employed to prepare a set of phthalimides (Scheme 7.51). However, the nature of the amine was seen to have an effect on the outcome of the reaction. Benzyl derivatives furnished somewhat lower yields, probably due to the reduced activities of these amines. Aromatic amines could not be included in the study as auto-induced ring-closure occurred during the conversion of the polymer-bound phthalic acid. 

Azole approach. Like phthalazinones, which can be formed from the reaction between phthalic acids and hydrazines, the thiazole analogues can be formed from thiazole-4,5-dicarboxylic acid derivatives. Other 4,5-substituted oxo groups react similarly to give a fused thiazole (451) (71BSF1491). 

Singlet oxygen oxidation of 3-substituted indoles in the presence of alcohols followed by treatment with sodium borohydride gives 2-alkoxy-3-hydroxyindolines in high yields. Further reaction with a nucleophile and a Lewis acid forms the basis of a synthesis of 2-substituted indoles (Scheme 70). This represents an alternative approach to CC bond formation at the 2-position of indoles to that involving the reaction of 2-lithioindoles with electrophiles. Isoindoles and indolizines are also preferentially oxidized in the five-membered ring to give phthalic acid and picolinic acid derivatives, e.g., 168, respectively. 

Methyl formate, ethyl formate, carboxylic acids and derivatives, acetic acid CH3COOCH, acetic anhydride CH3COOCOCH3, formic acid HCOOH, oxalic acid HOOCCOOH, phthalic anhydride C3H4O3 Acetaldehyde CH3CHO, acrolein H2C=CHCHO, formaldehyde HCHO, furfural C5H4O2... 

Naphthalene as such has several important uses. Its most common use is as a germicide or insecticide against the attacks of the moth miller larvae in the form of what is known as moth-balls. A more important use is as an enricher or carburetter of water gas for illuminating purposes. As it contains a large amount of carbon it burns with a very luminous flame and thus makes more luminous a weakly illuminating gas. The most important uses of all, however, are as a source of ortho-phthalic acid and in yielding derivatives which are used as dyes. 

Two mononitroxylenes can be derived, theoretically, from orthoxylene, three from metaxylene, and but one from paraxylene. It follows, therefore, that the xylene boiling at 142°, from which two mononitro derivatives can be prepared, is orthoxylene, and that the ones boiling at 139° and 138° have the meta and para structure, respectively. The application of the so-called absolute method leads to the establishment of the structure of the three xylenes, which can serve, therefore, as reference-compounds. The three hydrocarbons yield three dibasic acids on oxidation orthoxylene gives phthalic acid, metaxylene gives isophthalic acid, and paraxylene gives terephthalic acid. The three phthalic acids become, thus, reference-compounds. Other compounds can be readily converted into xylenes or phthalic acids, and can, therefore, be used in the determination of structure. Thus, the three dibromobenzenes can be converted into the three xylenes by Fittig s synthesis. The transformations establish the structure of the halogen derivatives. From these other compounds may be prepared. An example will be instructive. The dibromobenzene which melts at 89° is converted into paraxylene when treated with methyl iodide and sodium —... 

Alkyd resins number in the hundreds and are used in glossy paints and enamels— house, car, and artist s—as illustrated in Figure 27.9. Most are derived from benzene-1,2-dicarboxylic acid (o-phthalic acid) and 1,2,3-propanetriol (glycerol). Two of the hydroxyl groups of glycerol are converted to esters of o-phthalic acid the third is esterified with an unsaturated fatty acid that forms cross links to other chains. 

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