1: With sulfuric acid in water T=90°C; 5 h; Inert atmosphere; 2: With sodium nitrite in water T=0 - 20°C; Inert atmosphere; 3: With sulfuric acid in water T=90°C; 1 h; Inert atmosphere;

sulfuric acid RefluxLarge scale reaction;

1.1: SnCl2·2H2O / ethyl acetate / 50 °C / |Inert atmosphere 2.1: sulfuric acid / water / 5 h / 90 °C / |Inert atmosphere 2.2: 0 - 20 °C / |Inert atmosphere 2.3: 1 h / 90 °C / |Inert atmosphere View Scheme

1.1: thionyl chloride / methanol / 6 h / 0 °C / |Inert atmosphere; |Reflux 2.1: SnCl2·2H2O / ethyl acetate / 50 °C / |Inert atmosphere 3.1: sulfuric acid / water / 5 h / 90 °C / |Inert atmosphere 3.2: 0 - 20 °C / |Inert atmosphere 3.3: 1 h / 90 °C / |Inert atmosphere View Scheme

1: 2-bromo-4-hydroxybenzoic acid methyl ester With potassium carbonate in N,N-dimethyl-formamide T=20°C; 0.333333 h; Inert atmosphere; 2: methyl iodide in N,N-dimethyl-formamide T=0 - 20°C; 2 h; Inert atmosphere;