Description
Azaconazole is a sterol biosynthesis inhibitor with fungicidal action. It is moderately soluble in water, relatively volatile and may be persistent in aquatic systems. Azaconazole is moderately toxic to mammals but is not expected to bioaccumulate. It is moderately toxic to birds, fish and aquatic invertebrates.
Production Methods
Azaconazole is synthesised through a multi-step process involving the alkylation of 4-amino-4H-1,2,4-triazole. The production begins with the preparation of key intermediates, notably 1-(2,4-dichlorophenyl)-2-(1H-1,2,4-triazole-1-yl)ethanone. This compound is formed by reacting 2,4-dichlorophenyl precursors with triazole derivatives under controlled conditions. The final step involves coupling this intermediate with additional reagents to yield azaconazole.
Definition
ChEBI: A member of the class of dioxolanes that is 1,3-dioxolane substituted at position 2 by 2,4-dichlorophenyl and 1,2,4-triazol-1-ylmethyl groups. A fungicide used mainly in ornamental crops to control canker and other diseases. Azaconazole is moderately toxic
to mammals but is not expected to bioaccumulate. It is moderately toxic to birds, fish and aquatic invertebrates.
Manufacturing Process
A stirred and cooled (0°C) solution of 1-(2,4-diaminophenyl)-1-ethanone in a
concentrated hydrochloric acid solution, water and acetic acid was diazotated
with a solution of sodium nitrite in water. After stirring at 0°C, the whole was
poured onto a solution of copper (I) chloride in a concentrated hydrochloric
acid solution while stirring. The mixture was heated at 60°C. After cooling to
room temperature, the product was extracted twice with 2,2'-oxybispropane.
The combined extracts were washed successively with water, a diluted sodium
hydroxide solution and again twice with water, dried, filtered and evaporated,
yielding 1-(2,4-dichlorophenyl)-1-ethanone.
1-(2,4-Dichlorophenyl)-1-ethanon were dissolved in 1,2-ethanediol at heating.
While stirring bromine were added dropwise, without external heating. After
stirring at room temperature, 4-methylbenzenesulfonic acid and benzene were
added. The whole was stirred and refluxed overnight with water-separator.
The reaction mixture was evaporated and the residue was taken up in 2,2'-
oxybispropane. The resulting solution was washed successively once with a
dilute sodium hydroxide solution and 3 times with water, dried, filtered and
evaporated. The residue was distilled, yielding 2-(bromomethyl)-2-(2,4-
dichlorophenyl)-1,3-dioxolane.
6.9 parts of 1H-1,2,4-triazole in 150 parts of dimethylformamide were added
to a stirred solution of 2.3 parts of sodium in 120 parts of methanol. The
methanol was removed at normal pressure until the internal temperature of
130°C was reached. Then, 25 parts of 2-(bromomethyl)-2-(2,4-
dichlorophenyl)-1,3-dioxolane were added. The reaction-mixture was stirred
and refluxed for 3 h. It was allowed to cool to room temperature and poured
onto water. The precipitated product was filtered off, yielding 12 parts of 1-[2-
(2,4-dichlorophenyl)-1,3-dioxolan-2-yl-methyl]-1H-1,2,4-triazole, melting
point 109.9°C (crystallized from diisopropylether, activated charcoal).
