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Disinfectants and oxidizers

Phthalaldehyde

Also known as o-Phthalaldehyde, o-Phthaldialdehyde, 1,2-Benzenedicarboxaldehyde

CAS 643-79-8Formula C8H6O2Molar mass 134.13 g/molEC 211-402-2
GHS signal word: Danger. Pictograms: Flammable, Corrosive, Acute toxicity (severe), Harmful or irritant 121 suppliers listed Drug substance
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Phthalaldehyde chemical structure, C8H6O2, CAS 643-79-8
2D chemical structure

Key facts

What buyers check first

All properties
Appearance
Long, pale yellow needles from petroleum ether (MP 56-56.5 °C). Also reported as colorle…
Melting point
55.8 °C
Boiling point
83 °C
Density
Density (at 20 °C): 1.13 g/cm³
Flash point
132 °C
HS code
291229
Category
Disinfectants and oxidizers
UN number
UN 2923
Illustrative photo, off-white crystalline powder with an amber glass bottle on a laboratory bench
Typical packagingIllustrative packaging image, not the actual product

What is Phthalaldehyde?

Plain description, key identifiers and synonyms

Phthalaldehyde is a dialdehyde in which two formyl groups are attached to adjacent carbon centres on a benzene ring. It has a role as an epitope. It is a member of benzaldehydes and a dialdehyde.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
phthalaldehyde
CAS number
643-79-8 CAS number cross-checkedOther or deprecated CAS: 25750-62-3
EC number
211-402-2
Molecular formula
C8H6O2
UNII
4P8QP9768A
MDL number
MFCD00003335
InChIKey
ZWLUXSQADUDCSB-UHFFFAOYSA-N
InChI
InChI=1S/C8H6O2/c9-5-7-3-1-2-4-8(7)6-10/h1-6H
SMILES (canonical and isomeric)
C1=CC=C(C(=C1)C=O)C=O

Synonyms

  • o-Phthalaldehyde
  • o-Phthaldialdehyde
  • 1,2-Benzenedicarboxaldehyde
  • Phthalic aldehyde
  • ortho-Phthalaldehyde
  • benzene-1,2-dicarbaldehyde
  • Phthalic dialdehyde
  • Phthalic dicarboxaldehyde
  • Phthalyldicarboxaldehyde
  • Phthalaldialdehyde
  • ortho Phthalaldehyde
  • o-Phthalicdicarboxaldehyde
  • 1,2-Diformylbenzene
  • phtharal
  • Phtalaldehydes
  • Disopa
  • Orthophthaldialdehyde
  • ortho-Phthalic Aldehyde
  • o Phthalaldehyde
  • o Phthaldialdehyde
  • ortho Phthalic Aldehyde
  • Aldehyde, ortho-Phthalic
  • Safe OPA
  • Benzene-1,2-dicarboxaldehyde
  • Phthaldialdehyde
Show all 36 synonyms
  • o-Phthaldehyde
  • 2-Phthalaldehyde
  • 1,2-Benzenedicarbaldehyde
  • orthophthalaldehyde
  • OPA
  • OPTA
  • Phtharal (JAN)
  • 1,2-Phthalic dicarboxaldehyde
  • o-Phthalic dicarboxaldehyde
  • Phthaldialdehyde Reagent
  • phthalaldehyd

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

Appearance
Long, pale yellow needles from petroleum ether (MP 56-56.5 °C). Also reported as colorless powder (MP: 54 °C)exp.
Melting point
55.8 °Cexp.
Boiling point
83 °Cexp.
Density
Density (at 20 °C): 1.13 g/cm³exp.
Flash point
132 °Cexp.
Solubility
In water, 5 g/100 mL at 20 °Cexp.
Vapour pressure
0.0052 mm Hg at 21 °C (0.69 Pa)exp.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
134.13 g/molcalc.
Exact mass
134.0368 Dacalc.
LogP (octanol/water)
1.31calc.
Topological polar surface area
34.14 Ųcalc.
Hydrogen bond donors
0calc.
Hydrogen bond acceptors
2calc.
Rotatable bonds
2calc.
Heavy atoms
10calc.
Rings
1calc.
Aromatic rings
1calc.
Fraction sp3 carbons
0calc.
Formal charge
0calc.
Stereocentres
0calc.
Lipinski rule of five
Passes (0 violations)calc.

Calculated for screening. Confirm critical figures with the supplier.

Murcko scaffold

The ring system that remains when every side chain is removed

Murcko scaffold of this chemical, c1ccccc1

c1ccccc1

1 ring, 6 atoms, the Benzene ring system.

485,677 other chemicals share this scaffold

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS02: Flammable
Flammable
GHS05: Corrosive
Corrosive
GHS06: Acute toxicity (severe)
Acute toxicity (severe)
GHS07: Harmful or irritant
Harmful or irritant
GHS08: Serious health hazard
Serious health hazard
GHS09: Hazardous to the environment
Hazardous to the environment

Hazard statements

  • H228Flammable solid.
  • H301Toxic if swallowed.
  • H314Causes severe skin burns and eye damage.
  • H315Causes skin irritation.
  • H317May cause an allergic skin reaction.
  • H318Causes serious eye damage.
  • H335May cause respiratory irritation.
  • H373May cause damage to organs through prolonged or repeated exposure.
  • H400Very toxic to aquatic life.
  • H410Very toxic to aquatic life with long lasting effects.
Precautionary statements (32)
  • P210Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P240Ground and bond container and receiving equipment.
  • P241Use explosion-proof electrical, ventilating and lighting equipment.
  • P260Do not breathe dust, fume, gas, mist, vapours or spray.
  • P261Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P264Wash skin thoroughly after handling.
  • P264 + P265Wash skin thoroughly after handling. Do not touch eyes.
  • P270Do not eat, drink or smoke when using this product.
  • P271Use only outdoors or in a well-ventilated area.
  • P272Contaminated work clothing should not be allowed out of the workplace.
  • P273Avoid release to the environment.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P301 + P316If swallowed: Get emergency medical help immediately.
  • P301 + P330 + P331If swallowed: Rinse mouth. Do not induce vomiting.
  • P302 + P352If on skin: Wash with plenty of water.
  • P302 + P361 + P354If on skin: Take off immediately all contaminated clothing. Immediately rinse with water for several minutes.
  • P304 + P340If inhaled: Remove person to fresh air and keep comfortable for breathing.
  • P305 + P354 + P338If in eyes: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P316Get emergency medical help immediately.
  • P317Get medical help.
  • P319Get medical help if you feel unwell.
  • P321Specific treatment (see supplemental first aid instructions on the label).
  • P330Rinse mouth.
  • P332 + P317If skin irritation occurs: Get medical help.
  • P333 + P317If skin irritation or rash occurs: Get medical help.
  • P362 + P364Take off contaminated clothing. And wash it before reuse.
  • P363Wash contaminated clothing before reuse.
  • P370 + P378In case of fire: Use appropriate media to extinguish.
  • P391Collect spillage.
  • P403 + P233Store in a well-ventilated place. Keep container tightly closed.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.
UN number
UN 2923
Transport hazard class
8
Packing group
II

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

Phthalaldehyde suppliers

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All 121 suppliers
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Where suppliers are based

121 suppliers in 16 countries

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Phthalaldehyde price

Indicative price range per kg from live supplier offers

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Uses and applications

What the substance is used for, by industry and function

Reagents used to synthesize fluorescent derivatives for chemical analyses: Derivatized compound: primary amines. (From table).

Disinfectant. Reagent in fluorometric determination of primary amines and thiols.

/o-Phthalaldehyde/ ... in conjunction with 2-mercaptoethanol, is most often used in post-column detection of amino acids separated by conventional automated amino acid analysis.

Use classes: Pesticide transformation products.

Pharmacological actions

  • Disinfectants
  • Enzyme Inhibitors
  • Indicators and Reagents

Roles

  • epitope

Regulatory status

Inventories, regulations and trade controls that list this substance

Health and food

  • Active ingredient in FDA approved drug labels

United States

  • TSCA inventory (USA)
    Status: Active in US commerce

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Phthalaldehyde is traded under.

HS 2912.29Indicative HS code

Cyclic aldehydes without other oxygen function, other

World exports in 2024
$435M
+19.0% vs 2023, imports $484M
2019 to 2024
Top exporters
  1. China19.5%
  2. Japan17.4%
  3. India * partner reported13.0%
Top importers
  1. United States22.5%
  2. China9.2%
  3. Singapore8.4%

* Partner reported figures, a lower bound.

Reported customs values in USD, not prices.Full trade data

The HS code shown for Phthalaldehyde is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Phthalaldehyde, based on the data on this page

What is Phthalaldehyde?

Phthalaldehyde is a dialdehyde in which two formyl groups are attached to adjacent carbon centres on a benzene ring. It has a role as an epitope. It is a member of benzaldehydes and a dialdehyde.

What is the CAS number of Phthalaldehyde?

The CAS registry number of Phthalaldehyde is 643-79-8. Other or deprecated CAS numbers: 25750-62-3.

What is the molecular formula and weight of Phthalaldehyde?

The molecular formula of Phthalaldehyde is C8H6O2 and its molar mass is 134.13 g/mol.

What is Phthalaldehyde used for?

Reagents used to synthesize fluorescent derivatives for chemical analyses: Derivatized compound: primary amines. (From table). Disinfectant. Reagent in fluorometric determination of primary amines and thiols. /o-Phthalaldehyde/ ...

Is Phthalaldehyde hazardous?

Phthalaldehyde carries the GHS signal word "Danger". Main hazards: flammable solid, toxic if swallowed, causes severe skin burns and eye damage. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Phthalaldehyde?

Phthalaldehyde is usually classified under HS code 291229 (Cyclic aldehydes without other oxygen function, other). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Phthalaldehyde?

CompoundList lists 121 suppliers of Phthalaldehyde in China, United States, United Kingdom, Germany and 12 more. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

Where can I buy Phthalaldehyde in India?

3 suppliers in India list Phthalaldehyde on CompoundList. Filter the suppliers list by country and send a request to compare prices, grades and delivery times.

What is the price of Phthalaldehyde?

Suppliers quote Phthalaldehyde on request because prices depend on grade, purity, quantity and destination. A free request on CompoundList gets you several quotes to compare.

Guides for buyers

Practical guides that help when you source, ship or handle Phthalaldehyde

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Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
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