Description
Difenacoum, is also called 3-(3-biphenyl-4-yl-1,2,3,4-
tetrahydro-1-naphthyl)-4-hydroxycoumarin, consists of colorless crystals
which are insoluble in water, moderately to readily soluble
in acetone, chloroform, ethyl acetate, benzene.Difenacoum is synthesized by the condensation of 4-hydroxycoumarin and 3-biphenyl-4-yl-1,2,3,4-tetrahydro-1-naphthol (49).
Uses
Difenacoum is a 4-hydroxycouramin derivative. Difenacoum is a second generation anticoagulant rodenticide used against rodent pests such as rats and mice.
Definition
ChEBI: Difenacoum is a ring assembly, a member of benzenes and a member of naphthalenes.
Production Methods
Difenacoum is commercially produced through a multi-step organic synthesis that constructs its complex coumarin-based structure. The process typically begins with the preparation of a substituted 4-hydroxycoumarin core, which is then alkylated with a tetrahydronaphthalene derivative bearing a biphenyl substituent. This key step forms the 3-substituted coumarin backbone characteristic of difenacoum. The synthesis requires precise control of reaction conditions, including temperature and solvent choice, to ensure the correct stereochemistry and high purity of the final product.
Agricultural Uses
Rodenticide: Difenacoum is an anticoagulant that is effective against
rats and mice, including warfarin-resistant strains. It is used
in agriculture and urban rodent control as ready-to-use baits.
Trade name
COMPO®; MATRAK®; NEOSOREXA®
PELLETS; NEOSOREXA PP580®; RASTOP®;
RATAK®; RATRICK®; SILO; SOREXA GEL; STORM
Mechanism of action
Difenacoum is a second-generation anticoagulant rodenticide that disrupts the normal blood clotting mechanisms in its target species. It acts by blocking the vitamin K cycle and preventing the activation of vitamin K-dependent proteins disrupting the synthesis of essential blood clotting factors, resulting in increased bleeding tendency and eventually death. The primary mechanism of action involves the inhibition of the enzyme Vitamin K Epoxide Reductase Complex Subunit 1 (VKORC1), which is crucial for the synthesis of coagulation factors.
Safety Profile
A poison by ingestion and skincontact. When heated to decomposition it emits acridsmoke and irritating vapors.
Toxicity evaluation
Appearing in 1974, difenacoum was the first of the
new generation of anticoagulants to be commercialized for
the control of rodents resistant to warfarin and related
compounds (42). LD50 values (acute oral) for warfarinsusceptible
rodent strains are about a factor of 2 lower
than for warfarin-resistant strains. There is also a degree
of specificity. The compound is generally less toxic to
nontarget animals than to targets. A wide range of bait
types containing 0.005% difenacoum is available, including
meals, broken and whole grains, pellets, and wax blocks.
A 0.1% contact dust is no longer widely used. Resistance
to difenacoum was detected among a population of Norway
rats in the United Kingdom in 1978 (50). This remains a
problem of local importance but relatively low resistance
factors indicate that other behavioral factors also play a
significant role (51). Difenacoum resistance has also been
recorded in other European countries (39).
Pesticide Type
Rodenticide
