Isophthalic acid

Description

Isophthalic acid · CAS 121-91-5 · C8H6O4. UNII X35216H9FJ. Melting Point: 653 °F (USCG, 1999); Melting Point: 347 °C; Melting Point: 345-348 °C.

Identification

CAS Registry Number	121-91-5
PubChem CID	8496
Molecular formula	C8H6O4
IUPAC name	benzene-1,3-dicarboxylic acid
UNII (FDA)	X35216H9FJ

Computed Descriptors

Molecular Weight	166.13
XLogP3	1.7
Hydrogen Bond Donor Count	2
Hydrogen Bond Acceptor Count	4
Rotatable Bond Count	2
Exact Mass	166.02660867
Monoisotopic Mass	166.02660867
Topological Polar Surface Area	74.6
Heavy Atom Count	12
Formal Charge	0

Physical & Chemical Properties

Melting Point	653 °F (USCG, 1999)
Melting Point	347 °C
Melting Point	345-348 °C
Density	1.53 at 4 °C
Density	1.507 @ 20°C
Vapor Pressure	0.00000002 [mmHg]
Vapor Pressure	VP: 0.009 Pa (0.0675 mm Hg) at 100 °C
Vapor Pressure	0.068 [mm Hg] @100 °C
LogP	log Kow = 1.66
LogP	1.66

Physical description & handling notes

• Isophthalic acid is a white solid with a slight unpleasant odor. Sinks in water. (USCG, 1999)
• Dry Powder; Other Solid; Large Crystals; CBI; Liquid
• Colorless solid; [Hawley] Sublimes without decomposition; [Merck Index] Melting point = 347 deg C; [HSDB] Faintly beige powder; [MSDSonline]
• COLOURLESS CRYSTALLINE POWDER.
• Crystalline powder
• Colorless crystals

Regulatory Status

Regulatory & Food Contact

FDA Cumulative Estimated Daily Intake (CEDI): FCS FDA Inventory of Food Contact Substances Listed in 21 CFR: FCS FDA Inventory of Effective Food Contact Substance (FCS) Noti: FCS Isophthalic acid (CAS Reg. No. 121-91-5) As a monomer in the manufacture of ethylene terephthalate-isophthalate copolymers. As a monomer in the manufacture of ethylene terephthalate-isophthalate copolymers, except for use in contact w

GHS notification summary

91% (614 / 675)

GHS Hazard Classification

GHS notification summary	91% (614 / 675)

Documented Uses

• Used to make plastics, unsaturated polyester resins, alkyd resins, polyamides, and thermoplastic polyesters; Used as a co-monomer with terephthalic acid to make plastic bottles and specialty resins; [HSDB] Used in formulations for adhesives, inks, wire enamels, and dental materials; [CAMEO]
• Working with Glues and Adhesives [Category: Other]
• Plastic Composites Manufacturing [Category: Industry]
• CHEM INT FOR DIPHENYL ISOPHTHALATE
• CHEM INT FOR THE PLASTICIZER, DIOCTYL ISOPHTHALATE, DIMETHYL ISOPHTHALATE & DIETHYL ISOPHTHALATE
• CHEM INT FOR DIALLYL ISOPHTHALATE (CROSS LINKING AGENT)

Synonyms

ISOPHTHALIC ACID; 121-91-5; Benzene-1,3-dicarboxylic acid; 1,3-Benzenedicarboxylic acid; m-Phthalic acid; m-Benzenedicarboxylic acid; Acide isophtalique; Kyselina isoftalova; DTXSID3021485; X35216H9FJ; NSC-15310; DTXCID301485; CHEBI:30802; benzene-1,3-dicarboxylate;hydron; RefChem:7642; 204-506-4

Frequently Asked Questions

What are the CAS number and molecular formula of Isophthalic acid?

CAS 121-91-5; molecular formula C8H6O4; molecular weight — g/mol.

What other names is Isophthalic acid known by?

ISOPHTHALIC ACID, 121-91-5, Benzene-1,3-dicarboxylic acid, 1,3-Benzenedicarboxylic acid, m-Phthalic acid, m-Benzenedicarboxylic acid.

What is the regulatory status of Isophthalic acid?

Documented regulatory listings: FDA Cumulative Estimated Daily Intake (CEDI): FCS; FDA Inventory of Food Contact Substances Listed in 21 CFR: FCS; FDA Inventory of Effective Food Contact Substance (FCS) Noti: FCS.

Is Isophthalic acid classified as hazardous?

91% of GHS notifications report no hazard classification (614 of 675).

What are the key physical properties of Isophthalic acid?

Melting Point: 653 °F (USCG, 1999); Melting Point: 347 °C; Melting Point: 345-348 °C; Density: 1.53 at 4 °C.

Facts on this page are taken from PubChem (US National Library of Medicine) and Wikidata. Grade-specific data — assay, moisture, particle size, packaging, shelf life — is issued per batch on the COA and is not published here.