Phthalic acid, ortho

Monomer structure can affect the competition between cyclization and linear polymerization. For example, phthalic acid (ortho isomer) is more prone to cyclization than terephthalic acid (para isomer) at the very-low-molecular-weight end, for example, the dimer stage. The ortho structure makes more likely the conformations that are more favorable for cyclization. Stiff linear chains such as those formed in the reaction between an aromatic diamine and aromatic diacid chloride are much less prone to cyclization than the flexible chains formed from the corresponding aliphatic monomers. 

S nithesis from Phthalic Acid.—ortho-VhXha Q, acid yields a mono-brom derivative in which the bromine is ortho to one carboxyl and meta to the other, i.e., 1-2-dicarboxy 3-brom benzene. This being an ortho- hXhsX c acid yields an anhydride. This anhydride condenses... 

Methylene Chloride 70 NR Phthalic Acid (Ortho) 70t 212 Sodium Silicate... 

Di- and mono-esters of phthalic acid, an ortho-dicarboxylic acid derivative of benzene. These compounds are widely used as industrial plasticizers to coat polyvinylchloride surfaces of plastics used in food packaging and medical devices (iv drip bags, blood storage bags, etc.) and are common environmental contaminants. Several phthalate mono-esters are peroxisome proliferator chemicals and can activate the peroxisome proliferator-activated receptor PPAR. 

Until 1959, all the phthalic anhydride was made from coal tar naphthalene, the double-benzene ring compound also shown in Figure 18—3 was easily oxidized directly to phthalic acid. But with phthalic anhydride being only a small share of coal oil, and with the demand for phthalic anhydride escalating rapidly, coal tar became an inadequate source. The frantic search for an alternative route led to the development of the recovery process for ortho-xylene from refinery aromatics streams discussed in Chapter 3 and the... 

The phthalic acids are made by oxidation of the corresponding xylene isomer. They are used to make plasticizers and alkyd and polyester resins and fibers. Ortho-phthalic acid usually is not isolated because it loses a molecule of water so easily, forming phthalic anhydride, the commercially traded form of this strain of phthalic acid. 

Ortho-xylene Phthalic acid COOH 1 COOH Phthalic anhydride... 

Acetic anhydride (acetic acid), phthalic anhydride (ortho-xylene), and maleic anhydride (butane or benzene). Phthalic anhydride has a benzene ring as its unique feature, with its three double bonds maleic anhydride has its single, but reactive, double bond. Acetic anhydride has only the... 

Synonyms Bis(2-ethylhexyl) 1,2-benzenedicarboxylate bis(2-ethylhexyl) ortho-phthalate DEHP dioctyl phthalate di-sec octyl phthalate ethylhexyl phthalate 2-ethylhexyl phthalate octyl phthalate phthalic acid di(2-ethylhexyl) ester phthalic acid dioctyl ester... 

Carboxylic acids react with aryl isocyanates, at elevated temperatures to yield anhydrides. The anhydrides subsequently evolve carbon dioxide to yield amines at elevated temperatures (70—72). The aromatic amines are further converted into amides by reaction with excess anhydride. Ortho diacids, such as phthalic acid [88-99-3], react with aryl isocyanates to yield the corresponding N-aryl phthalimides (73). Reactions with carboxylic acids are irreversible and commercially used to prepare polyamides and polyimides, two classes of high performance polymers for high temperature applications where chemical resistance is important. Base catalysis is recommended to reduce the formation of substituted urea by-products (74). 

The ion m/z 149, which is characteristic of phthalic acid esters, arises as the result of the operation of this ortho effect. 

Using this methodology, iodocubanes are prepared by decarboxylative iodination in presence of 2,2,2-trifluoroiodoethane595. ortho-Bromobenzoic acid derivatives are prepared from phthalic acids (equation 69)596. 

The regioselectivity in certain aromatic chlorinations by hypochlorite is also pH-depen-dent. The ortho/para ratio in phenol chlorination increased from 0.64 at pH = 4 to 4.3 at pH = 10794. Selective 4-chlorination of phthalic acid is obtained in aqueous sodium hypochlorite solution795. Iodination of phenols in aqueous systems is also pH-dependent and the ortho iodophenol yield grows at stronger basic media796,797. 

Phthalic acid itself is the ortho isomer. The meta isomer is called isophthalic acid, and the para isomer is called terephthalic acid. 

Ward, H.L., Cooper, S.S. (1930) The system, benzoic acid, ortho phthalic acid, water. J. Phys. Chem. 24, 1484-1493. 

Oxidation of Xylene.—Just as toluene on oxidation has the methyl group converted into carboxyl yielding a mono-carboxyl or mono-basic acid, benzoic acid, so the xylenes by oxidation yield di-carboxyl or di-basic acids of the corresponding ortho, meta or para constitution. The two methyl groups are, moreover, possible of oxidation one at a time so that intermediate mono-carboxyl or mono-basic acids result in which one methyl group remains. The di-basic acids are known as phthalic acids and the mono-basic acids as toluic acids. 

Phthalic acid is a crystalline solid which melts at 184° with the loss of water and the formation of an anhydride. It is very slightly soluble in cold water, but quite easily soluble in hot water and in alcohol. The loss of water with the formation of an anhydride is characteristic of the ortho-phthalic acid as distinguished from the meta- and para-phthalic acids which do not yield anhydrides. 

Synthesis from Phthalic Acid and Naphthalene.— This was found when anthranilic acid was synthesized from ortho-phthalic acid which, as has been stated, may in turn be synthesized from naphthalene, a cheap abundant compound. The conversion of naphthalene into or//fo-phthalic acid we have given (p. 689) as resulting from chlorination and subsequent oxidation. 

The details of this synthesis will be explained under naphthalene (p. 766). The synthesis of anthranilic acid from ortho-i hthalic acid takes place according to the following reactions. Phthalic acid, or better phthalic anhydride, by treatment with ammonia yields phthal-amidic acid, which in turn yields phthalimide. 

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. 

Yields ortho-Phthalic Acid.—The simplest proof that naphthalene does contain a benzene ring is found in the fact that on oxidation it yields phthalic acid and always the ortho compound. This would indicate... 

Chlor Naphthalenes.—Another series of reactions which support the view just discussed, that in naphthalene there are present two nuclei either one of which is a benzene ring, is found in Laurent s work on the chlorine substitution products of naphthalene. When naphthalene is chlorinated it yields different chlor naphthalenes. Two of these are important in this place, viz., a tetra-chlor naphthalene, C10H4CI4 and a penta-chlor naphthalene, C10H3CI5. Now the first one must have all four chlorines linked to one nucleus because on oxidation it yields ortho-phthalic acid, as below. The penta-chlor compound must of necessity have at least one of the chlorines linked to the second nucleus as only four are possible of being linked to one nucleus. Now this compound on oxidation yields not mono-chlor phthalic acid but tetra-chlor phthalic acid. The reactions may be represented as follows ... 

Addition Products.—The halogen addition products of naphthalene ,re more easily formed than are the substitution products. The tetra-chlor compound is of special interest and has been referred to. We have stated that naphthalene is oxidized to or//fo-phthalic acid. This oxidation was originally carried out not with naphthalene itself but with naphthalene tetra-chloride, CioHgCU. When naphthalene is treated with chlorine (potassium chlorate, KCIO3 and hydrochloric acid HCl), addition takes place and the tetra-chlor addition product is formed. By the further action of the chlorine, as an oxidizing agent, the tetra-chloride is converted into ortho-phthalic acid. 

In the preceding reactions the benzene nucleii have been numbered I and II in order to follow their course through the various transformations. It may be readily seen, therefore, that the benzene nucleus in brom anthraquinone which remains as a benzene ring in t r//f )-phthalic acid is the nucleus which does not contain bromine. This was derived from the benzene constituent of the s)mthesis and, in anthraquinone, it is linked to the carbonyl groups by ortho positions. Therefore, both benzene nucleii in anthraquinone are linked by ortho positions and both are derived from true benzene ring compounds or may remain as benzene rings on the decomposition of the quinone. 

The remarkable thing is, that while there are ten possible di-brom or di-hydroxy anthraquinones, the particular one necessary was obtained by Graebe and Liebermann. The positions of the two hydroxyl groups were determined by Baeyer and Caro. When alizarin is heated pyro-catechinol, i-2-di-hydroxy benzene, is obtained. Also when pyro-catechinol is heated with ortho- hXhaXic acid and sulphuric acid alizarin results. This last synthesis is analogous to that of anthraquinone from benzene and o //io-phthalic acid (p. 796). 

This relationship of alizarin to pyro-catechinol proves that the two hydroxyl groups must be ortho to each other, but this condition is possible if the hydroxyls are either 1-2 or 2-3. Baeyer and Caro established the positions as 1-2 as follows. When phenol is heated with ortho-phthalic acid and sulphuric acid two mono-hydroxy anthraquinones are obtained. 

This is exactly analogous to the oxidation of naphthalene to ortho-phthalic acid and the conversion of this into benzene (p. 689). 

Naphthalene to Anthranilic Acid.—Such a cheap source was found in naphthalene which was converted into anthranilic acid, orthoamino benzoic acid, and this by treatment with chlor acetic acid yields phenyl glycine ortho-carboxylic acid. The complete synthesis is as follows Naphthalene is oxidized to or// o-phthalic acid which then yields phthalic anhydride. This with ammonia, as ammonium carbonate, yields phthalimide or phthalamidic acid. 

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