Phthalic acid, dissociation constant

Fig. 19.7. Relationship between acid dissociation constant pK and frequency (v) of the antisymmetric stretching vibration of salts of carboxylic acids in DjO solution. 1, Trifluoroacetic 2, trichloroacetic 3, dichloroacetic 4, cyanoacetic 5, chloroacetic 6, 2-phenoxypropionic 7, methoxyacetic 8, formic 9, glycollic 10, lactic 11, 3-hydroxybutyric 12, acetic 13, propionic 14,cyclohexane carboxylic 15, polyacrylic 16, malonic 17, phthalic 18, benzoic 19, salicylic and 20. polyguluronic. polygalacturonic, galacturonic, alginic, hyaluronic, and chondroitin sulfates A, B, and C. ( C) From Goulden and Scott, 1968 (O) from Chapman et at. 1964. The pK values are from references given in Goulden and Scott (1968). (Goulden and Scott, 1968.)...

Smdies of the thermal degradation of several aromatic acids have been reported. Phthalic acid (80), but not isophthalic acid (81) or terephthalic acid (82), decomposes via dehydration to its anhydride at 140-160 °C. However, (81) and (82) and benzoic acid are thermally stable below 200 °C. Dissociation constants of all 19 isomers of methyl-substimted benzoic acids (83) have been measured in methanol and DMSO. From the pA a values, the substiment effects of the methyl groups were calculated and tentatively divided into polar and steric effects. Also, in the case... 

The pH of a 0.05 molar solution of acid potassium phthalate is 4.00 the first stage dissociation constant of phthalic acid is 1.3 X 10 what is pk2 for this acid ... 

Hamer WJ, Pinching GD and Acree SF, First dissociation constant of o-phthalic acid and related pH values of phthalate buffers from 0 to 60 , /. Res. Nat. Bur. Stand., 35, 539-564 (1945) Hamer WJ and Acree SF, /. Res. Nat. Bur. Stand., 35,381-416 (1945). NB Used electrochemical cell wiBiout liquid junction potentials detailed procedures were required to extrapolate ionic strengBi effects to zero. 

Standardized solutions of tertiary amines such as tripropylamine and N-ethyl piperidine have been used by Siggia and Floramo [1] to titrate maleic and phthalic acids in their anhydrides. This method is rather specific for maleic acid since the acids which might be included in the determination are those with dissociation constants of 10 , or greater, in water. This would not include acids such as succinic (dissociation constant, 7 10 ) or fumaric (9.3 10 ). 

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