sodium dithionite in water T=50°C; 2.5 h;

1.1: nitric acid / acetic acid / 4 h / 0 °C 2.1: sodium dithionite / water / 3 h / 50 °C 2.2: 0.5 h / 65 °C View Scheme

1.1: phosphorous pentoxide / anhydrous xylene / 18 h / Reflux 2.1: nitric acid / acetic acid / 4 h / 0 °C 3.1: sodium dithionite / water / 3 h / 50 °C 3.2: 0.5 h / 65 °C View Scheme

1.1: urea / 0.5 h / 220 °C 2.1: phosphorous pentoxide / anhydrous xylene / 18 h / Reflux 3.1: nitric acid / acetic acid / 4 h / 0 °C 4.1: sodium dithionite / water / 3 h / 50 °C 4.2: 0.5 h / 65 °C View Scheme

1.1: tetra-(n-butyl)ammonium iodide; potassium carbonate / N,N-dimethyl-formamide / 1 h / 100 °C 1.2: 50 - 85 °C 2.1: water; potassium hydroxide / methanol / 4 h / 20 °C 3.1: urea / 0.5 h / 220 °C 4.1: phosphorous pentoxide / anhydrous xylene / 18 h / Reflux 5.1: nitric acid / acetic acid / 4 h / 0 °C 6.1: sodium dithionite / water / 3 h / 50 °C 6.2: 0.5 h / 65 °C View Scheme

acetic acid in toluene 4 h; Heating / reflux;

1: acetic acid; N,N-dimethyl-formamide dimethyl acetal / toluene / 4 h / 105 °C 2: acetic acid / toluene / 5 h / 60 °C 3: toluene / 5 h / 125 °C View Scheme

1: With acetic acid in isopropyl alcohol 4 h; Reflux; 2: With hydrogenchloride in isopropyl alcohol T=20°C; pH=3.0 - 4.0; Product distribution / selectivity;

1: acetic acid; N,N-dimethyl-formamide dimethyl acetal / toluene / 4 h / 105 °C 2: acetic acid / toluene / 5 h / 60 °C 3: toluene / 5 h / 125 °C 4: hydrogenchloride / methanol / 0.05 h / 15 - 20 °C View Scheme

acetic acid in N,N-dimethyl-formamide T=110°C; 2 h;