3.4- Dihydroxy phthalic acid

Luminescence titrimetry has been developed chiefly for acid-base titrations. Therefore, fluorescence pH-indicators are now widely used. Their application is based on changes of fluorescence spectrum upon the addition of a proton or its loss. At present, over 200 fluorescence pH-indicators are available the structural formulae of the most the widely applied indicators are given in Table 8. Some of them (No. 2, 8, 9, 12, 16, 17, 23, 25 and 29) and also, primuline, tripaflavine, and rhodamine 6G are widely used as adsorption fluorescence indicators. The titration end point can be detected in this case because of the differences in of the indicator in the adsorbed state and in solution. Redox fluorescence indicators including rhodamines B and 6 G, 3,6-dihydroxy-phthalic acids, complexes of Ru(II) with 2,2 -dipyridyl or 1,10-phenanthroline and other... 

Intermediates and Products of Side Reactions under Colors, Appendix IIIC, using the following Sample Solution Transfer 2 g of sample, accurately weighed, into a 100-mL volumetric flask dissolve in and dilute to volume with water. Calculate the concentrations of 2-(2,4-dihydroxy-3,5-diiodobenzoyl) benzoic acid, iodine, phthalic acid, sodium iodide, and triio-doresorcinol, using the following absorptivities ... 

Tetracyclic structures emanate in the following way. A mixture of phthalic acid chlorideandL-2-acetyl-2-amino-1,2,3,4-tetrahydro-5,8-dimethoxynaphthalenein dichloromethane treated during 3 hours at ambient temperature with aluminium chloride gave after solvent removal and work-up with aqueous oxalic acid, L-9-acety l-9-acetylamino-6,11-dihydroxy-7,8,9,10-tetrahydro-5,12-naphthacene-dione in 90% yield (ref.57). 

Attempts had been made to synthesise polyesters based on phthalic acid as the diacid component, but these products were amorphous, had low softening points, and were rapidly attacked by organic solvents and acids and bases. Research into polyesters made by the reaction of terephthalic acid (or esters thereof) with aliphatic diols, led to the discovery of polyesters of high commercial value poly(alkylene terephthalate)s [4]. This pairing of diols with terephthalic acid eventually led to the most commercially successful aromatic polyesters, but other synthetic pathways were also investigated towards such products in the early days of polyester development. These included the self-condensation of hydroxy acids of the structure -H0-R-Ph-C02H, where R-OH is para to the acid group and R is -(CH2)- or -(CH2)2- [5], and reactions of aliphatic diacids with 1,4-dihydroxy benzene and similar aromatic diols [6, 7]. Also synthesised about the same time were polyesters based on C2-Cg aliphatic diols and any of the isomeric naphthalene dicarboxylic acids [8]. 

Dihydroxy-1,3-indandiones from phthalic acid esters... 

A good example of difference in molecular requirements for linear and network polymers is the formation of polyesters from dihydroxy or trihydroxy alcohols. As was shown on page 554 for diamines, reaction of a dihydroxy alcohol with a diacid gives a linear copolymer. If a trihydroxy alcohol is used instead, a network copolymer is formed. An example is the class of ALKYD resins (Fig. 26.3), produced from glycerol and phthalic acid, and used as ingredients of paints and varnishes. 

Preparation. The precursor, ll,12-dihydroxy-9,10-quinone (3), has been prepared by two methods, neither of which is very well documented. In one phthalic anhydride is condensed with succinic acid and potassium acetate at 200-220° for 2 hrs. to give a,j8-diphthylidene-ethane (I, ethinediphthalide ), which on treatment with sodium methoxide and methanol, followed by acidification, is isomerized in part to the dihydroxynaphthacenequinone (3, isoethinediphthalide ), and in part to bis-diketohydrindene (2). The yield of the desired (3) is very low. A second... 

The principal unsaturated acids used are maleic and fumaric. Saturated acids, usually phthalic and adipic, may also be included. The function of these acids is to reduce the amount of unsaturation in the final resin, making it tougher and more flexible. The acid anhydrides are often used if available and applicable. The dihydroxy alcohols most generally used are ethylene, propylene, diethylene, and dipropylene glycols. Styrene and diallyl phthalate are the most common cross-linking agents. Polyesters are resistant to corrosion, chemicals, solvents, etc. 

Liebermann discovered the reaction between nitrous acid and phenols and secondary amines named after him. He prepared amino-naphthols from nitro-naphthols, synthesised the dihydroxyanthraquinones anthrarufin and chrysazin, and studied the reduction of anthraquinone. Another dihydroxy-anthraquinone, quinizarin, was discovered by F. Grimm by heating hydro-quinone with phthalic anhydride. 

Polyesters are macromolecules made by reacting a diacid or dianhydride with a dihydroxy compound (diols). To make unsaturated polyesters, maleic anhydride or fumeric acid is used in addition to a saturated acid, which provides unsaturation in the structure. The most commonly used anhydrides are maleic anhydride (unsaturated) and phthalic anhydride (saturated). The commonest diols are ethylene glycol or propylene glycol. Use of an unsaturated anhydride is very critical to provide unsaturation in the structure, which is utilised to cure the resin by free-radical polymerisation. The chemical reaction for the synthesis of UPE is shown in Figure 2.13. 

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