Phthalic acid

Phthalic acid

Names
Preferred IUPAC name Benzene-1,2-dicarboxylic acid
Other names 1,2-Benzenedioic acid Phthalic acid Benzene-1,2-dioic acid ortho-Phthalic acid Dicarboxylbenzene Carboxylbenzoic acid 1,2-Phenylenedicarboxylic acid Phenylene-1,2-dicarboxylic acid
Identifiers
CAS Number	88-99-3 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:29069 N
ChemSpider	992 N
ECHA InfoCard	100.001.703
EC Number	201-873-2
PubChem CID	1017
UNII	6O7F7IX66E Y
CompTox Dashboard (EPA)	DTXSID8021484
SMILES OC(=O)c1ccccc1C(=O)O
Properties
Chemical formula	C8H6O4
Molar mass	166.132 g/mol
Appearance	white solid
Density	1.593 g/cm3, solid
Melting point	207 °C (405 °F; 480 K)
Solubility in water	0.6 g / 100 mL
Acidity (pKa)	2.89, 5.51
Magnetic susceptibility (χ)	-83.61·10−6 cm3/mol
Hazards
NFPA 704 (fire diamond)	2 0 0
Related compounds
Related carboxylic acids	Isophthalic acid Terephthalic acid
Related compounds	Phthalic anhydride Phthalimide Phthalhydrazide Phthaloyl chloride Benzene-1,2- dicarboxaldehyde
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

In a field of chemistry called "Organic Chemistry", which mainly involves the study of carbon-based molecules, phthalic acid, is a dicarboxylic acid, which refers to the two COOH groups present in the molecule. The two carboxylic acids are present on an aromatic ring, here benzene, which is where the systematic name "Benzene-1,2-dicarboxylic acid" is from.

Phthalic acid is one of three structural isomers of benzenedicarboxylic acid. Which refers to the placement of the two carboxylic acids on the benzene-ring. If there were a gap between them it would be the molecule isophthalic acid, with the systematic name Benzene-1,3-dicarboxylic acid, while if the acid groups were opposing each other, it would be terephthalic acid, with the systematic name Benzene-1,4-dicarboxylic acid.

Synthesis

The molecule "Napthalene", when oxidised by potassium permanganate, or similarly strong oxidizers, gives the molecule Phthalic anhydride, with through hydrolysis with hot water, gives Phthalic acid.

References

1. ↑ Several melting points are reported, for example: (i) 480. K (NIST website), (ii) 210−211 °C with decomposition (Sigma-Aldrich on-line), (iii) 191 °C in a sealed tube (Ullmann's Encyclopedia of Industrial Chemistry), (iv) 230 °C with conversion to phthalic anhydride and water (J.T.Baker MSDS).
2. ↑ "PHTHALIC ACID". hazard.com.
3. ↑ Brown, H.C., et al., in Baude, E.A. and Nachod, F.C., Determination of Organic Structures by Physical Methods, Academic Press, New York, 1955.
4. ↑ "Oxidation of Naphthalene to Phthalic Anhydride". public.websites.umich.edu. Retrieved 2024-06-15.
5. ↑ Noller, Carl R. (1965). Chemistry of Organic Compounds (3rd ed.). Philadelphia: W. B. Saunders. pp. 602.