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Phthalic acid

CAS Number
88-99-3
EC Number
201-873-2
Chemical Formula
C8H6O4
Molecular Weight
166.13 g/mol

Description

Phthalic acid (CAS 88-99-3 ), also known as orthophthalic acid, is an aromatic dicarboxylic acid used across pharmaceutical, cosmetic, and specialty chemical manufacturing. It functions primarily as a pH buffer, acidulant, and catalyst precursor in synthesis and formulation processes. In pharmaceutical manufacturing, phthalic acid serves as a buffering agent in tablet coatings and controlled-release formulations where precise pH management affects drug dissolution profiles. Cosmetic formulators incorporate it into pH-adjustment systems for creams and serums. These rinse-off products require stability across a defined acidity range which is critical to shelf life. As a catalyst precursor, it is used in the production of phthalate esters and specialty resins where the acid form is the preferred starting material. In preservation systems, its acidic character contributes to microbial control in formulations where low-pH environments are part of the preservation strategy. This versatility makes it a staple in modern chemical synthesis and industrial applications. Phthalic acid is supplied as a white crystalline powder. Pharmaceutical-grade material meeting USP and BP specifications is available for regulated applications, ensuring high purity and compliance with international standards. Technical-grade product serves industrial synthesis and resin manufacturing where high-volume production is required. Packaging options typically range from kilogram-scale bags to bulk sacks depending on the specific application volume and logistics. Contact us for supply of Phthalic acid Request Quote

Other Names (Synonyms)

orthophthalic acid | o-dicarboxybenzene | o-carboxybenzoic acid | o-benzenedicarboxylic acid | Naphthalinic acid | Alizarinic acid | M 2 | Sunftal 20

Key Technical Features

  • High Purity Grade standard
  • Consistent Batch Quality
  • Full Regulatory & REACH Support
  • Global Logistics Network enabled

Physical Properties

Melting Point191 °C (decomp)
Boiling Point214.32°C (rough estimate)
Density1.593 g/cm³ @ Temp: 15 °C
Flash Point168 °C
Appearancewhite crystals
ColorWhite
FormPowder
Water Solubility7 g/L (25 ºC)
Vapor Pressure7.8 hPa (191 °C)
Refractive Index1.5100 (estimate)
pH2 (5g/l, H2O, 20℃)
Log P0.73 at 20℃

Safety & Handling

Danger
GHS08· Health HazardGHS05· CorrosiveGHS07· Irritant

Hazard Statements

H315Causes skin irritation
H318Causes serious eye damage
H319Causes serious eye irritation
H335May cause respiratory irritation

Precautionary Statements

P203Obtain, consult and follow expert instructions for use.
P261Avoid breathing dust/fume/gas/mist/vapours/spray.
P264Wash … thoroughly after handling.
P271Use only outdoors or in a well-ventilated area.
P280Wear protective gloves/protective clothing/eye protection/face protection.
P317Get emergency medical help.
P318IF exposed or concerned, get medical advice.
P319Get medical advice/attention if you feel unwell.
P321Specific treatment (see … on this label).
P405Store locked up.
P501Dispose of contents/container in accordance with local regulations.
P265Wash … thoroughly after handling.
P352IF ON SKIN: Wash with plenty of water.
P340IF INHALED: Remove person to fresh air and keep comfortable for breathing.
P317Get emergency medical help.
P317If eye irritation persists: Get medical advice/attention. Get emergency medical help.
P364Take off contaminated clothing and wash it before reuse.
P233Store in a well-ventilated place. Keep container tightly closed.
P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.

Trade & Regulatory

HS Code29173980
Storage Class11 - Combustible Solids
WGK (Germany)1