Pyrogallol
[CAS 87-66-1]

Identification

• Classification: Natural product >> Natural phenols
• Name: Pyrogallol
• Synonyms: 1,2,3-Benzenetriol; 1,2,3-Trihydroxybenzene; C.I. 76515
• Molecular Formula: C₆H₆O₃
• Molecular Weight: 126.11
• CAS Registry Number: 87-66-1
• EC Number: 201-762-9
• SMILES: C1=CC(=C(C(=C1)O)O)O

Properties

• Density: 1.5±0.1 g/cm³ Calc.^*, 1.453 g/mL (Expl.)
• Melting point: 132 - 134 °C (Expl.)
• Boiling point: 309.0 °C 760 mmHg (Calc.)^*, 309 °C (Expl.)
• Flash point: 164.3±16.9 °C (Calc.)^*
• Index of refraction: 1.677 (Calc.)^*, Refraction index Data source (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07;GHS08 Warning
• Risk Statements: H302-H312-H332-H341-H412
• Safety Statements: P203-P261-P264-P270-P271-P273-P280-P301+P317-P302+P352-P304+P340-P317-P318-P321-P330-P362+P364-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Germ cell mutagenicity	Muta.	2	H341
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	4	H312
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Acute toxicity	Acute Tox.	4	H302
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H336
Carcinogenicity	Carc.	2	H351
Skin sensitization	Skin Sens.	1B	H317
Acute toxicity	Acute Tox.	3	H301
Chronic hazardous to the aquatic environment	Aquatic Chronic	4	H413
Skin sensitization	Skin Sens.	1	H317

• Transport Information: UN 1814; UN 2811

chemBlink Chemical Story

Pyrogallol matters because three adjacent phenolic hydroxyl groups make pyrogallol readily oxidized, a property once exploited in oxygen analysis and photographic development. This connection between molecular structure and observable behavior is more informative than a simple list of uses. CAS 87-66-1 identifies the substance in this chemBlink record, while its practical significance comes from the way its functional groups, composition, or material structure control reactivity and physical properties.

The broader lesson is that chemical identity alone does not determine performance. Conditions such as pH, temperature, formulation, concentration, molecular distribution, or biological environment can decide whether the same underlying chemistry is useful, inactive, or hazardous. For chemists, Pyrogallol is therefore a useful case study in connecting molecular-scale behavior with a real laboratory, industrial, biological, or materials-science outcome.

References: PubChem: Pyrogallol, CAS 87-66-1; historical analytical and photographic chemistry literature

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