P

Phthalic acid

IUPAC: phthalic acid

C8H6O4 Acids CAS 88-99-3
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Quick Reference
Formula / NotationC8H6O4
CAS Number88-99-3
Molecular Weight166.13
Melting Point410 to 412 °F (decomposes) (NTP, 1992)
Boiling PointDecomposes (NTP, 1992)
Density1.593 at 68 °F (NTP, 1992) - Denser than water; will sink
Solubilityless than 1 mg/mL at 68 °F (NTP, 1992)
AppearancePhthalic acid appears as white crystals or fine white powder. (NTP, 1992)
Also Known As88-99-3; 1,2-benzenedicarboxylic acid; o-phthalic acid; benzene-1,2-dicarboxylic acid; o-dicarboxybenzene; o-benzenedicarboxylic acid; Acide phtalique; Kyselina ftalova; ortho-phthalic acid; 6O7F7IX66E
CategoryAcids

What is Phthalic acid?

Phthalic acid is a benzenedicarboxylic acid cosisting of two carboxy groups at ortho positions. It has a role as a human xenobiotic metabolite. It is a conjugate acid of a phthalate(1-).

Formula & Notation

C8H6O4

IUPAC Name: phthalic acid

Other Names / Synonyms: 88-99-3; 1,2-benzenedicarboxylic acid; o-phthalic acid; benzene-1,2-dicarboxylic acid; o-dicarboxybenzene; o-benzenedicarboxylic acid; Acide phtalique; Kyselina ftalova; ortho-phthalic acid; 6O7F7IX66E

Properties & Characteristics

Appearance: Phthalic acid appears as white crystals or fine white powder. (NTP, 1992). Molecular formula: C8H6O4. Molecular weight: 166.13 g/mol. Boiling point: Decomposes (NTP, 1992). Melting point: 410 to 412 °F (decomposes) (NTP, 1992). Density: 1.593 at 68 °F (NTP, 1992) - Denser than water; will sink. Solubility: less than 1 mg/mL at 68 °F (NTP, 1992). Vapor pressure: 0.00000064 [mmHg]. LogP: 0.7.

Physical Data

PropertyValue
Melting Point410 to 412 °F (decomposes) (NTP, 1992)
Boiling PointDecomposes (NTP, 1992)
Density1.593 at 68 °F (NTP, 1992) - Denser than water; will sink
Molecular Weight166.13
Solubilityless than 1 mg/mL at 68 °F (NTP, 1992)
AppearancePhthalic acid appears as white crystals or fine white powder. (NTP, 1992)

Uses & Applications

Used in industrial chemical synthesis, fertilizer production, battery electrolytes, metal processing, and laboratory acid-base reactions.

Safety Information

Corrosive. Causes severe burns to skin, eyes, and respiratory tract. Wear appropriate PPE including gloves, goggles, and lab coat. Consult SDS before use.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Phthalic acid
Formula C8H6O4
CAS Number 88-99-3
Molecular Weight 166.13
Category Acids
Synonyms 88-99-3; 1,2-benzenedicarboxylic acid; o-phthalic acid; benzene-1,2-dicarboxylic acid; o-dicarboxybenzene; o-benzenedicarboxylic acid; Acide phtalique; Kyselina ftalova; ortho-phthalic acid; 6O7F7IX66E

Frequently Asked Questions

Phthalic acid is a benzenedicarboxylic acid cosisting of two carboxy groups at ortho positions. It has a role as a human xenobiotic metabolite. It is a conjugate acid of a phthalate(1-).

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Editorial standards: Chemical data is sourced from peer-reviewed literature, CAS Registry, NIST WebBook, and PubChem. Safety information reflects guidance from OSHA, ECHA, and IAEA. For educational purposes only — always consult official SDS documentation and qualified professionals before handling chemicals.