Phthalic acid

Phthalic acid
Phthalic acids
Ball-and-stick model of the phthalic acid molecule
Preferred IUPAC name
Benzene-1,2-dicarboxylic acid
Other names
1,2-Benzenedioic acid
Phthalic acid
Benzene-1,2-dioic acid
ortho-Phthalic acid
3D model (JSmol)
ECHA InfoCard100.001.703
EC Number201-873-2
Molar mass166.14 g/mol
Appearancewhite solid
Density1.593 g/cm3, solid
Melting point 207 °C (405 °F; 480 K)[3]
0.6 g / 100 mL [1]
Acidity (pKa)2.89, 5.51[2]
-83.61·10−6 cm3/mol
NFPA 704
Related compounds
Isophthalic acid
Terephthalic acid
Related compounds
Phthalic anhydride
Phthaloyl chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Phthalic acid is an aromatic dicarboxylic acid, with formula C6H4(CO2H)2. It is an isomer of isophthalic acid and terephthalic acid. Although phthalic acid is of modest commercial importance, the closely related derivative phthalic anhydride is a commodity chemical produced on a large scale.[4]


Phthalic acid is produced by the catalytic oxidation of naphthalene or ortho-xylene directly to phthalic anhydride and a subsequent hydrolysis of the anhydride.[4]

Phthalic acid was first obtained by French chemist Auguste Laurent in 1836 by oxidizing naphthalene tetrachloride.[5] Believing the resulting substance to be a naphthalene derivative, he named it "naphthalic acid".[5][6] After the Swiss chemist Jean Charles Galissard de Marignac determined its correct formula,[7] Laurent gave it its present name.[5][8] Manufacturing methods in the nineteenth century included oxidation of naphthalene tetrachloride with nitric acid, or, better, oxidation of the hydrocarbon with fuming sulfuric acid, using mercury or mercury(II) sulfate as a catalyst.[5]

Other Languages
العربية: حمض الفثاليك
تۆرکجه: فتالیک اسید
català: Àcid ftàlic
Deutsch: Phthalsäure
Ελληνικά: Φθαλικό οξύ
español: Ácido ftálico
Esperanto: Ftalata acido
euskara: Azido ftaliko
français: Acide phtalique
հայերեն: Ֆթալաթթու
italiano: Acido ftalico
latviešu: Ftalskābe
magyar: Ftálsav
Nederlands: Ftaalzuur
日本語: フタル酸
polski: Kwas ftalowy
português: Ácido ftálico
română: Acid ftalic
српски / srpski: Ftalna kiselina
srpskohrvatski / српскохрватски: Ftalna kiselina
svenska: Ftalsyra
українська: Фталева кислота
Tiếng Việt: Axít phthalic