Metacetamol

Metacetamol (developmental code name BS-749), also known as 3-hydroxyacetanilide and AMAP, is a non-toxic regioisomer of paracetamol with analgesic and antipyretic properties, but has never been marketed as a drug.^[1][2]

Metacetamol

Clinical data
Other names	N-Acetyl-meta-aminophenol; AMAP; meta-acetyl-aminophenol; 3-hydroxyacetanilide
Identifiers
IUPAC name N-(3-Hydroxyphenyl)acetamide
CAS Number	621-42-1 Y
PubChem CID	12124
ChemSpider	11626 Y
UNII	V942ZCN81H
ChEBI	CHEBI:76987 Y
ChEMBL	ChEMBL9419 Y
CompTox Dashboard (EPA)	DTXSID3022089
ECHA InfoCard	100.009.717
Chemical and physical data
Formula	C8H9NO2
Molar mass	151.165 g·mol−1
3D model (JSmol)	Interactive image
Melting point	146 to 149 °C (295 to 300 °F)
SMILES CC(=O)NC1=CC(=CC=C1)O
InChI InChI=InChI=InChI=1S/C8H9NO2/c1-6(10)9-7-3-2-4-8(11)5-7/h2-5,11H,1H3,(H,9,10) Y Key:QLNWXBAGRTUKKI-UHFFFAOYSA-N Y

Metacetamol is known to have several polymorphs.^[3] Form II is metastable, while form I is stable.^[3] Metacetamol polymorph II transforms to form I upon water moisture or direct contact with water and other popular solvents.^[3] Metacetamol II form may be obtained on cooling in narrow temperature regime.^[4]