Reaction #61685

Reaction equation

2-fluoro-5-methoxyaniline

potassium cyanate

→

N-(2-Fluoro-5-methoxyphenyl)urea

Yield 69.2%

Solvents

acetic acid

water

water

Conditions

Workup

1. 1
   Otherquenched into water (500 mL)
2. 2
   FiltrationThe crude product was filtered
3. 3
   Washwashed with water (1.2 L), heptane (50 mL)
4. 4
   workup.ADDITIONslurred in a mixture of tert-butylmethylether (100 mL) and ethyl acetate (5 mL) for 5 minutes at ambient temperature
5. 5
   FiltrationThe product was filtered
6. 6
   Washwashed with tert-butylmethylether (30 mL)
7. 7
   Otherdried in vacuo at 40° C.

Procedure

To a stirred solution of 2-fluoro-5-methoxyaniline (35.15 g, 249 mmol) in acetic acid (99 mL) and water (177 mL) at 35° C. was added potassium cyanate (40 g, 0.49 mol) in water (170 mL) over 20 minutes under N2. The mixture was stirred at 40° C. for 20 min and at 18 to 20° C. for 2 h, and then quenched into water (500 mL). The crude product was filtered, washed with water (1.2 L), heptane (50 mL) and slurred in a mixture of tert-butylmethylether (100 mL) and ethyl acetate (5 mL) for 5 minutes at ambient temperature. The product was filtered, washed with tert-butylmethylether (30 mL) and dried in vacuo at 40° C. to give N-(2-Fluoro-5-methoxyphenyl)urea (31.75 g, 69%) as a light-brown solid.

Source