Potassium Hydroxide → Methyl 5-hydroxy-4-methoxy-2-nitrobenzoate

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Reaction Conditions

Reaction Steps

A mixture of 500 g methyl 4,5-dimethoxy-2-nitro-benzoate and 625 g potassium hydroxide in 2300 ml of water is heated to 95° C. for 18.5 h. After cooling, the mixture is filtered clear and the filtrate is diluted with 3 l water. The solution is combined with 950 ml acetic acid and after 1 h the precipitate is filtered off. The precipitate is suspended in 3250 ml ethyl acetate and then 100 ml of water and 200 ml 12N hydrochloric acid are added. After 1.5 h the phases are separated and the aqueous phase is extracted with 700 ml ethyl acetate. The combined organic phases are dried on magnesium sulphate and after filtration they are evaporated down. The mixture is evaporated again with 200 ml methylcyclohexane. The residue is refluxed together with 1600 ml of methanol and 100 ml conc. sulphuric acid for 16.5 h. The mixture is evaporated down until crystallisation begins. 1000 ml of water are added and the mixture is stirred until a homogeneous suspension is obtained. The precipitate is filtered off, washed with 500 ml of water and suspended in 1000 ml of water. After 1.5 h stirring the precipitate is filtered off and washed with 500 ml of water. After the filter cake is dried, 364 g product are obtained.

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