Methyl 2-ethoxy-4-nitrobenzoate → 2-Ethoxy-4-aminobenzoic acid

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Reaction Steps

4.05 g (21.7 mmol, 1 eq) 2-hydroxy-4-nitro-benzoic acid are dissolved in 40 mL MeOH and 1.8 mL (24.8 mmol, 1.14 eq) thionyl chloride are slowly added dropwise. The mixture is refluxed for 2 h at 50° C. and stirred for another 2 h. After cooling the volatile constituents are eliminated in vacuo and 4.36 g of the crude methyl 2-hydroxy-4-nitro-benzoate are obtained, which are reacted without further purification. 1 g (5.1 mmol, 1 eq) of the methyl ester are dissolved in 25 mL DMF, 2.1 g (15.3 mmol, 3 eq) potassium carbonate are added and then 1.4 mL (18.8 mmol, 3.7 eq) bromoethane are added dropwise. The reaction mixture is stirred for 16 h at RT, then poured into 100 mL water and the pH is adjusted with concentrated aqueous hydrochloric acid to pH 3. It is extracted twice with 100 mL EE, dried on MgSO4 and after the elimination of all the volatile constituents in vacuo 1.28 g of methyl 2-ethoxy-4-nitro-benzoate are obtained. 1.28 g (5.06 mmol, 1 eq) of the nitro compound are dissolved in 50 mL MeOH, a spatula tip of Raney nickel is added and the reaction mixture is stirred in the autoclave under a hydrogen pressure of 4 bar for 16 h. The catalyst is filtered off through Celite® and the filtrate is freed in vacuo of all the volatile constituents. 0.99 g of the aniline are obtained [MS-ESI+: 351 (M+H)+].

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