Pyrocatechol
CAS 120-80-9 · EC 204-427-5 · C6H6O2
Also known as catechol, pyrocatechin, 1,2-dihydroxybenzene
Handle chemistry safely
Wear gloves and eye protection, work with good ventilation, and read the supplier’s safety data sheet before use. Hazard information here is a summary, not a replacement for it. Dispose of all photographic chemistry correctly, in line with local laws and your local authority’s guidance. Never mix waste solutions, and check the supplier’s safety data sheet before disposing of anything.
Hazards
Official EU classification (harmonised under CLP Annex VI).
Signal word: Danger
Serious health hazard · Acute toxicity
- H350 May cause cancer.
- H341 Suspected of causing genetic defects.
- H311 Toxic in contact with skin.
- H301 Toxic if swallowed.
- H315 Causes skin irritation.
- H319 Causes serious eye irritation.
UK and EU rules
- CLP Annex VI Carc. 1B (H350) and Muta. 2 – harmonised entry 604-016-00-4 (ATP13)
Photographic uses
- staining developing agent (Pyrocat-HD)
Sources
- ECHA CHEM substance record: Pyrocatechol (100.004.025)
- ECHA CHEM – C&L Inventory (harmonised CLP Annex VI and notified classifications) and legal obligations (chem.echa.europa.eu APIs: /api-cnl-inventory/harmonized|industry, /api-obligation-substance/v1)
- REACH Annex XVII entries 28–30 (CMR substances – supply to general public) (Annex XVII entries 28, 29, 30; latest consolidated act CELEX 32025R1731)
Checked October 2026.