Organic Acids
REACH
Phthalic acid
CAS Number
88-99-3
EC Number
201-873-2
What is Phthalic acid?
Phthalic acid (CAS 88-99-3), also known as orthophthalic acid, is an aromatic dicarboxylic acid.
Where is Phthalic acid used?
- Pharmaceutical manufacturing: buffering agent in tablet coatings and controlled-release formulations where precise pH management affects drug dissolution profiles
- Cosmetic formulators: pH-adjustment systems for creams and serums
- Catalyst precursor: production of phthalate esters and specialty resins
- Preservation systems: acidic character contributes to microbial control
- It functions as a pH buffer, acidulant, and catalyst precursor in synthesis and formulation.
Good to know: Pharmaceutical-grade material meeting USP and BP specifications is available for regulated applications. Technical-grade product serves industrial synthesis and resin manufacturing.
Commercial specifications
- Packaging options range from kilogram-scale bags to bulk sacks
Other Names (Synonyms)
orthophthalic acid|o-dicarboxybenzene|o-carboxybenzoic acid|o-benzenedicarboxylic acid|Naphthalinic acid|Alizarinic acid|M 2|Sunftal 20
What are the physical properties of Phthalic acid?
Melting Point 191 °C (decomp)
Boiling Point 214.32°C (rough estimate)
Density 1.593 g/cm³ @ Temp: 15 °C
Flash Point 168 °C
Appearance white crystals
Color White
Form Powder
Water Solubility 7 g/L (25 ºC)
Vapor Pressure 7.8 hPa (191 °C)
Refractive Index 1.5100 (estimate)
pH 2 (5g/l, H2O, 20℃)
Log P 0.73 at 20℃
How is Phthalic acid classified and handled safely? Learn More
Danger
GHS08· Health Hazard GHS05· Corrosive GHS07· Irritant
Hazard Statements
H315 Causes skin irritation
H318 Causes serious eye damage
H319 Causes serious eye irritation
H335 May cause respiratory irritation
Precautionary Statements
P203 Obtain, consult and follow expert instructions for use.
P261 Avoid breathing dust/fume/gas/mist/vapours/spray.
P264 Wash … thoroughly after handling.
P271 Use only outdoors or in a well-ventilated area.
Which trade and regulatory codes apply to Phthalic acid?
HS Code 29173980
Storage Class 11 - Combustible Solids
WGK (Germany) 1