Chemical substance record

Phentolamine

50-60-2C₁₇H₁₉N₃O281.359 g/mol

Organic/Inorganic Small MoleculeChEBI source record

A substituted aniline that is 3-aminophenol in which the hydrogens of the amino group are replaced by 4-methylphenyl and 4,5-dihydro-1H-imidazol-2-ylmethyl groups respectively. An α-adrenergic antagonist, it is used for the treatment of hypertension. — ChEBI

Safety references

Safety documents & references

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Identity & molecular properties

Source-linked values

CAS number	50-60-2	ChEBI ↗
Molecular formula	C₁₇H₁₉N₃O	ChEBI ↗
Molar mass	281.359 g/mol	ChEBI ↗
Monoisotopic mass	281.15281 Da	ChEBI ↗
Formal charge	0	ChEBI ↗
ChEBI identifier	CHEBI:8081	ChEBI ↗

Cross-source molecular data

PubChem

Molar mass	281.35 g/mol	PubChem ↗
Exact mass	281.152812238 Da	PubChem ↗
Computed XLogP	2.6	PubChem ↗
Topological polar surface area (Å²)	47.9	PubChem ↗
H-bond donors	2	PubChem ↗
H-bond acceptors	3	PubChem ↗
Rotatable bonds	4	PubChem ↗

PubChem computed values are shown separately from the ChEBI record. An exact InChIKey match was used to connect the records. Molecular descriptors do not describe a supplied product’s purity, particle size or performance.

Names & structural identifiers

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Source preferred name

phentolamine

IUPAC name

3-[(4,5-dihydro-1H-imidazol-2-ylmethyl)(4-methylphenyl)amino]phenol

InChIKey

MRBDMNSDAVCSSF-UHFFFAOYSA-N

SMILES

Cc1ccc(N(CC2=NCCN2)c2cccc(O)c2)cc1

InChI

InChI=1S/C17H19N3O/c1-13-5-7-14(8-6-13)20(12-17-18-9-10-19-17)15-3-2-4-16(21)11-15/h2-8,11,21H,9-10,12H2,1H3,(H,18,19)

Names & synonyms

3-[(4,5-dihydro-1H-imidazol-2-ylmethyl)(4-methylphenyl)amino]phenolfentolaminaphentolaminumRegitinaRegitineRogitine

Names are supplied by ChEBI. Trade names and related synonyms may describe a broader product context.

Classification & relationships

ChEBI ontology

imidazolesChEBI parent class · 24780 ↗phenolsChEBI parent class · 33853 ↗substituted anilineChEBI parent class · 48975 ↗tertiary amino compoundChEBI parent class · 50996 ↗

phenols organic heterocyclic compound organic molecular entity

Roles recorded in ChEBI

cardiovascular drugvasodilator agentalpha-adrenergic antagonistophthalmology druganti-obesity agenthyperglycemic agent

Database role annotations describe reported biological or chemical roles; they are not product approvals or recommendations for use.

Mass ↔ amount of substance

Calculated from sourced mass

Amount

Input unit

Equivalent amount

0.00355418 mol

Uses 281.359 g/mol from ChEBI. Assumes the substance described by this record; no purity or concentration correction is applied.

Elemental composition

Theoretical mass fractions

C

Carbon · 17 atoms

72.57%

N

Nitrogen · 3 atoms

14.94%

H

Hydrogen · 19 atoms

6.81%

O

Oxygen · 1 atom

5.69%

Calculated theoretical mass fractions from the reported formula and PubChem periodic-table atomic masses. These are not assay or purity results.

Research & patent references

Selected source associations

Effects of imidazoline and nonimidazoline alpha-adrenergic agents, including xylazine, medetomidine, yohimbine, tolazoline, and atipamezole, on aggregation of bovine and equine platelets. ↗American journal of veterinary research · 2013 Mar · PMID 23438114

Reversal of pulpal and soft tissue anesthesia by using phentolamine: a prospective randomized, single-blind study. ↗Journal of endodontics · 2013 Apr · PMID 23522530

US2503059 · Patent reference ↗Patent cross-reference supplied by ChEBI. Association alone does not establish claim scope.

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Sources & record history

Checked 27 Sep 2026

Identity, formula, mass, synonyms & ontologyEMBL-EBI ChEBI · CHEBI:8081

Release 255, 9 September 2026. ChEBI three-star (manually annotated) source entry. View original record ↗ · CC BY 4.0

Additional molecular descriptorsNCBI PubChem · CID 5775 · retrieved 2026-09-27

PubCAS formats source data, connects references and computes explicitly labelled conversions. CAS cross-references are supplied by ChEBI; they do not constitute CAS verification or endorsement.

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