ETHIRIMOL

Ethirimol is a systemic fungicide with both protective and curative actions. It controls mainly powdery mildew (Erysiphe gmminis) on barley, wheat and oats. Ethirimol can be applied as a seed dressing, as a foliar spray or directly to the soil in the root zone.

Ethirimol is a pyrimidine based fungicide with wide applications such as controlling leaf spot of sugar beet.

Fungicide.

ChEBI: An aminopyrimidine that is 2-ethylaminopyrimidin-4-one carrying butyl and methyl substituents at positions 5 and 6 respectively. A fungicide first marketed in 1970 and used as a seed treatment for diseaases such as damping-off, it is not licensed for use w thin the European Union.

Ethirimol is susceptible to photodegradation and it also degrades extensively in soil to yield CO2 and unextractable soil-bound residues. Metabolism in plants and animals is extensive to yield up to 16 metabolites. Elimination in animals was rapid following oral dosing. Metabolism in soil, plants and animals follows common pathways which include N-dealkylation, hydroxylation of the butyl group and conjugation.

Ethirimol (1) is stable to hydrolytic degradation in buffered solutions at pH 5, 7 and 9 at 22°C. It degraded under aqueous photolysis test conditions with a half-life (DT₅₀) of ca. 3 weeks. The primary photolytic degradation reactions include the opening of the pyrimidine ring to yield ethylguanidine (2), urea (3) and 4-butylpyrazolidine-3,5-dione (4) (Cavell et al., 1974c).