Physical and Chemical Characteristics

Classification: Rodenticide

Common name

warfarin (BSI, E-ISO, BAN); warfarine ((m) F-ISO); coumafène (France); zoocoumarin (USSR); coumarins (JMAF, also applied to coumatetralyl (q.v.)); no name (The Netherlands)

IUPAC name

(RS)-4-hydroxy-3-(3-oxo-1-phenylbutyl)coumarin; 3-(a-acetonylbenzyl)-4-hydroxycoumarin

Chemical Abstracts name

4-hydroxy-3-(3-oxo-1-phenylbutyl)-2H-1-benzopyran-2-one

CAS RN

[81-81-2] unstated stereochemistry; [5543-58-8] (R)-(+)- isomer; [5543-57-7] (S)-(-)- isomer

Stability

Very stable, even to strong acids.

Form

The racemate forms colourless crystals

Mol. wt.308.3

Solubility

In water 17 mg/l (20 ºC). Very slightly soluble in benzene, diethyl ether and cyclohexane. Moderately soluble in methanol, ethanol, and isopropanol. In acetone 65, chloroform 56, dioxane 100 (all in g/l, 20 ºC). Dissolves in aqueous alkalis with the formation of water-soluble salts. Sodium salt: in water up to 400 g/l; insoluble in organic solvents.

Formulation types

AB; CB; CP; GB; RB; Gel

Oral

Acute oral LD50 for rats 186, mice 374 mg/kg. Oral LD50 for rats 1, pigs 1, cats 3, dogs 3, cattle 200 (all mg/kg daily for 5 days).

Other

Organ damage is observed, as well as inhibition of blood coagulation. Only slightly dangerous to humans and domestic animals when used as directed, but care must be taken with young pigs, which are especially susceptible.

Toxicity class

WHO (a.i.) Ib