Substance profile
Phthalic Anhydride
Phthalic Anhydride is white, lustrous needles with a mild odor.
01 · Identification
What Phthalic Anhydride is
Phthalic Anhydride is white, lustrous needles with a mild odor. Its molecular formula is C8H4O3 and its molecular weight is 148.11 g/mol. It boils at 285 °C, melts at 131 °C.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
02 · Identifiers
Phthalic Anhydride identifiers and molecular data
Phthalic Anhydride CAS number and EC number
Phthalic Anhydride molecular formula and molecular weight
03 · GHS classification
Phthalic Anhydride hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Phthalic Anhydride pictograms and signal word
Phthalic Anhydride hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Acute toxicity - oral GHS chapter 3.1 | Category 4 | H302 | GHS07 |
| Skin corrosion/irritation GHS chapter 3.2 | Category 2 | H315 | GHS07 |
| Serious eye damage/eye irritation GHS chapter 3.3 | Category 1 | H318 | GHS05 |
| Respiratory sensitisation GHS chapter 3.4 | Category 1 or 1A or 1B | H334 | GHS08 |
| Skin sensitisation GHS chapter 3.4 | Category 1 or 1A or 1B | H317 | GHS07 |
| Specific target organ toxicity - single exposure GHS chapter 3.8 | Category 3 | H335 | GHS07 |
Where two values are shown with “or”, the hazard statement is shared by more than one category or by more than one class, and the code alone does not say which. H272, for example, belongs to oxidising liquids and to oxidising solids — the physical state decides. The binding answer for a specific entry is in the CLP Annex VI table itself.
Phthalic Anhydride hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H302 | Harmful if swallowed. |
| H335 | May cause respiratory irritation. |
| H315 | Causes skin irritation. |
| H318 | Causes serious eye damage. |
| H334 | May cause allergy or asthma symptoms or breathing difficulties if inhaled. |
| H317 | May cause an allergic skin reaction. |
This page lists only the codes assigned to Phthalic Anhydride. The full reference lives on the hazard statements hub, the precautionary statements hub and the GHS pictograms hub.
Safety Data Sheet
Getting an SDS for Phthalic Anhydride
A Safety Data Sheet is written for a product, not for a substance: the supplier of the grade you actually buy issues it, so two suppliers of Phthalic Anhydride issue two different sheets. That is why there is no single authoritative SDS for a substance to download — what there is, is the job of collecting the sheets for the products you hold and keeping them current as suppliers revise them.
04 · Precautionary statements
Phthalic Anhydride precautionary statements
CLP Annex VI assigns 16 precautionary statements to Phthalic Anhydride. They are grouped the way a label groups them: what to do before handling, what to do when something has already happened, how to store it and how to dispose of it.
Prevention
What to do before and during handling so the hazard never happens.
Response
What to do once exposure, spillage or fire has already happened.
Reading the notation. … is a blank the supplier fills in — not a truncated sentence.· [square brackets] mark a part printed only when it applies.
05 · Names in the regulation
Phthalic Anhydride name in 23 EU languages
CLP Annex VI Part 3 is published in every language edition of the regulation, and the identification column is written out in each of them. Nothing below is translated by us: each line is the name as that edition prints it. Under Art. 18(2) the substance name from Annex VI is a lawful product identifier, so this is the wording to put on a label going to that market — and where the cell lists several designations, any one of them qualifies.
| Language | Name in CLP Annex VI Part 3 |
|---|---|
| Bulgarian български | фталов анхидрид |
| Spanish español | Anhídrido ftálico |
| Czech čeština | ftalanhydrid |
| Danish dansk | phthalsyreanhydrid |
| German Deutsch | Phthalsäureanhydrid |
| Estonian eesti | ftaalanhüdriid |
| Greek ελληνικά | φθαλικός ανυδρίτης |
| English English | phthalic anhydride |
| French français | anhydride phtalique |
| Croatian hrvatski | ftalni anhidrid |
| Italian italiano | anidride ftalica |
| Latvian latviešu | ftalskābes anhidrīds |
| Lithuanian lietuvių | ftalio anhidridas |
| Hungarian magyar | ftálsav-anhidrid |
| Maltese Malti | anidride ftaliku |
| Dutch Nederlands | ftaalzuuranhydride |
| Polish polski | bezwodnik ftalowy |
| Portuguese português | anidrido ftálico |
| Romanian română | anhidridă ftalică |
| Slovak slovenčina | ftalanhydrid |
| Slovenian slovenščina | anhidrid ftalne kisline |
| Finnish suomi | ftaalihappoanhydridi |
| Swedish svenska | ftalsyraanhydrid |
All 23 language editions of Annex VI carry this entry. Irish is the twenty-fourth official EU language and has no line here for a different reason: no consolidated CLP text has ever been published in Irish, so there is no Irish edition of Annex VI to quote a name from. Source: consolidated CLP, CELEX 02008R1272, language editions. © European Union, https://eur-lex.europa.eu — only the electronic Official Journal of the European Union is authentic.
06 · Label elements
Phthalic Anhydride GHS label elements
Everything CLP Annex VI fixes for Phthalic Anhydride, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Phthalic Anhydride
- Harmful if swallowed.
- May cause respiratory irritation.
- Causes skin irritation.
- Causes serious eye damage.
- May cause allergy or asthma symptoms or breathing difficulties if inhaled.
- May cause an allergic skin reaction.
- Avoid breathing dust/fume/gas/mist/vapours/spray.
- Wash … thoroughly after handling.
- Do not eat, drink or smoke when using this product.
- Contaminated work clothing should not be allowed out of the workplace.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF SWALLOWED:
- IF ON SKIN:
- IF IN EYES:
- Immediately call a POISON CENTER/doctor/…
- Call a POISON CENTER/doctor/… if you feel unwell.
- Get medical advice/attention.
- Rinse mouth.
- If skin irritation occurs:
- If skin irritation or rash occurs:
- Remove contact lenses, if present and easy to do. Continue rinsing.
- Wash with plenty of water/…
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Phthalic Anhydride in the GHS label constructor →
07 · Health hazards
Phthalic Anhydride health hazards and exposure limits
Phthalic Anhydride hazard summary
Exposure to phthalic anhydride may occur during its use as a chemical intermediate in the plastics industry. The acute (short-term) effects from exposure to phthalic anhydride in humans consists of irritation to the eyes, respiratory tract, and skin, but no permanent injury is observed. Chronic (long-term) effects observed in workers exposed to phthalic anhydride included conjunctivitis, rhinitis, rhinoconjunctivitis, bronchitis, and irritation of the skin and mucous membranes of the respiratory tract. Animal studies indicate that chronic exposure to phthalic anhydride vapor causes congestion, irritation, and injury to lung cells. No studies are available on the reproductive, developmental, or carcinogenic effects of phthalic anhydride in humans. EPA has not classified phthalic anhydride for carcinogenicity.
Source: EPA Hazardous Air Pollutants
Phthalic Anhydride carcinogenicity classification
Studied by the US National Toxicology Program: TR-159: Bioassay of Phthalic Anhydride for Possible Carcinogenicity (CASRN 85-44-9) (1979 )
An IARC group and a CLP classification answer different questions. IARC judges whether the evidence for cancer in humans is strong enough; CLP Annex VI is the legally binding EU classification. A substance can carry one and not the other.
Phthalic Anhydride occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 12.0 [mg/m3] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 2 ppm (12 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| PEL | TWA 12 mg/m3 (2 ppm) See Appendix G | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 1 ppm (6 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| REL | TWA 6 mg/m3 (1 ppm) | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 60 mg/m3 (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 60.0 [mg/m3] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| IDLH | 60 mg/cu m | Hazardous Substances Data Bank (HSDB) |
These are United States values. The European Union sets its own indicative and binding limits, and the figure that applies at a given workplace is the one in the local regulation — not the one shown here.
08 · Physical and chemical properties
Phthalic Anhydride properties
Every value is shown with the conditions it was measured under and the source it came from. Where sources disagree, all values are listed rather than one being picked — the difference is usually a different form of the substance, not an error.
Phthalic Anhydride boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 285.3 °C (545.5 °F) | HSDB | |
| 295 °C (563 °F) | NIOSH |
Phthalic Anhydride melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 131.4 °C (268.5 °F) | HSDB | |
| 130.56 °C (267 °F) | NIOSH | ||
| 130.78 °C (267.4 °F) | CAMEO |
Phthalic Anhydride density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 1.2 g/cm³ | molten | HSDB |
| 1.53 g/cm³ | Flake | NIOSH | |
| 1.53 g/cm³ | ICSC |
Phthalic Anhydride solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | In water, 6,000 mg/L at 25 °C | at 25 °C | HSDB |
| In water, 6,200 mg/L at 26 °C; 5,964 mg/L at room temperature | at 26 °C | HSDB | |
| Decomposes (NTP, 1992) | decomposes | CAMEO |
Phthalic Anhydride vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 0.0015 mmHg | NIOSH | |
| 0.0002 mmHg | at 20 °C | CAMEO | |
| 0.000517 mmHg | at 25 °C | HSDB |
Phthalic Anhydride flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 151.67 °C (305 °F) | HSDB |
Phthalic Anhydride autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 570 °C (1058 °F) | HSDB |
Phthalic Anhydride lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 1.7 % by volume | HSDB |
Phthalic Anhydride upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 10.5 % by volume | HSDB | |
| 10.4 % by volume | CAMEO |
Phthalic Anhydride vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 6.6 (air = 1) | HSDB | |
| 5.1 (air = 1) | CAMEO |
Phthalic Anhydride odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | Air: 0.053 ul/l; odor safety class C; C= Less than 50% of distracted persons perceive warning of TLV. | HSDB | |
| 0.32-0.72 mg/cu m | HSDB | ||
| Odor Threshold Low: 0.05 [mg/m3] | Haz-Map |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Phthalic Anhydride fire and explosion behaviour
These are descriptions rather than measured values, so they are kept out of the table above and quoted here with the source that reported them.
Phthalic Anhydride fire potential
Combustible solid
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Phthalic Anhydride storage and handling
Phthalic Anhydride safe storage
Separated from combustible substances, reducing agents, strong oxidants, strong bases, strong acids and food and feedstuffs. See Chemical Dangers. Ventilation along the floor. Dry. Well closed. Store only in original container.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Phthalic Anhydride storage conditions
Chemical stability: Stable under recommended storage conditions.
Source: Hazardous Substances Data Bank (HSDB)
Phthalic Anhydride incompatible materials
Strong oxidizers, water [Note: Converted to phthalic acid in hot water].
Source: Hazardous Substances Data Bank (HSDB)
Phthalic Anhydride reactivity
PHTHALIC ANHYDRIDE reacts exothermically with water. The reactions are sometimes slow, but can become violent when local heating accelerates their rate. Acids accelerate the reaction with water. Incompatible with acids, strong oxidizing agents, alcohols, amines, and bases. Undergoes exothmeric nitration with fuming nitric acid-sulfuric acid and may give mixtures of the potentially explosive phthaloyl nitrates or nitrites or their nitro derivatives [Chem. & Ind. 20:790. 1972]. Phthalic anhydride reacts violently with CuO at elevated temperatures [Park, Chang-Man, Richard J. Sheehan. "Phthalic Acids and Other Benzenepolycarboxylic Acids" Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc. 2005]. Mixtures of phthalic anhydride and anhydrous CO2 explode violently if heated [Leaflet No. 5, Inst. of Chem., London, 1940].
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Phthalic Anhydride in the storage compatibility matrix →
11 · Transport
Phthalic Anhydride UN number and transport classification
Transport classification is a separate system from the GHS classification above. It decides how a package is marked and how a load may be carried; it does not follow from the workplace label, and the workplace label does not follow from it. The entries below are linked by CAS number, never by name.
Phthalic Anhydride under UN 2214 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| PHTHALIC ANHYDRIDE with more than 0.05 % of maleic anhydride | 8 | C4 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 8 is “Corrosive substances” (ADR 2.1.1.1).
United States · 49 CFR 172.101 Hazardous Materials Table
| Proper shipping name (column 2) | Class or division | PG | Labels (column 6) |
|---|---|---|---|
| Phthalic anhydride with more than .05 percent maleic anhydride | 8 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 8 is “Corrosive material” (49 CFR 173.2).
12 · Questions
Phthalic Anhydride — frequently asked questions
What is the CAS number of Phthalic Anhydride?
The CAS number of Phthalic Anhydride is 85-44-9. Its EC number is 201-607-5.
What is the chemical formula of Phthalic Anhydride?
The molecular formula of Phthalic Anhydride is C8H4O3 and its molecular weight is 148.11 g/mol.
What does a Phthalic Anhydride label have to show?
Under CLP Annex VI the label for Phthalic Anhydride carries the pictograms Health hazard, Corrosion and Exclamation mark and the signal word is Danger.
Is Phthalic Anhydride flammable?
CLP Annex VI assigns Phthalic Anhydride no flammability hazard class. That is not a statement that it cannot burn: the harmonised list only records the hazards that were assessed for it. The flash point reported for it is 151.67 °C (305 °F) (HSDB).
Is Phthalic Anhydride a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Phthalic Anhydride. Annex VI is a list of agreed classifications, not a list of substances found safe, so this is an absence of a classification rather than a clean bill of health.
What is the exposure limit for Phthalic Anhydride?
The US occupational exposure limit reported for Phthalic Anhydride is 12.0 [mg/m3] (Haz-Map, Information on Hazardous Chemicals and Occupational Diseases). Limits differ by country: the EU sets its own indicative and binding values, and the figure that applies at a given workplace is the one in the local regulation.
What is the boiling point of Phthalic Anhydride?
The boiling point reported for Phthalic Anhydride is 285.3 °C (545.5 °F) (HSDB).
What is the melting point of Phthalic Anhydride?
The melting point reported for Phthalic Anhydride is 131.4 °C (268.5 °F) (HSDB).
How should Phthalic Anhydride be stored?
Chemical stability: Stable under recommended storage conditions. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Phthalic Anhydride
Keep going: substances starting with P, or search the whole database by name, CAS number, pictogram or signal word.