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Propiconazole, 1-[[2-(2,4-dichlorophenyl)-4-propyl-1, 3-dioxol-2-yl[methyl]-1H-1,2,4-triazole, commercially know as “Tilt” is a systemic foliar fungicide for cereals and is widely used in agriculture. The aim of this project was to develop an economically feasible process for the production of propiconazole and to maximise the yields of the intermediates in the developed process. Processes investigated included the original Ciba-Geigy process. In addition an investigation into the synthesis and characterisation of the impurities formed, and reported to be formed in each step of the reaction process was carried out and seven of the reported impurities were synthesised. One impurity was shown not to be present in the reaction process. In addition a new impurity was identified, synthesised and characterised. The synthesis of propiconazole was initiated with ethanone-1-(2,4-dichlorophenyl) which under-went a condensation reaction with 1,2-pentanediol to yield 1, 3-dioxolane-2-(2,4-dichlorophenyl )-2-methyl-4-n-propyl. 1,3-Dioxolane-2-(2,4-dichlorophenykl)-2-methyl-4-n-propyl was then brominated in dichloromethane to yild 1,3-dioxolane-2(2,4 dichlorophenyl)-2-bromomethyl-4-n-propyl. Finally 1,3-dioxolane-2(2,4-dichlorophenyl)-2-bromomethys-4-n-propyl under-went nucleophlic substitution with a sodium triazole salt in dimethyl-sulphoxide at 160°C for 16hrs to yield propiconazole in 45%yield. The final phase of the project involved the scale up of the reaction process in order to evaluate any problems that might result in an industrial scale up.
Delaney, H. (2000). Synthesis of the fungicide propiconazole a systemic foliar fungicide. Masters dissertation. Technological University Dublin. doi:10.21427/D7HK60