3-Bromo-4-Fluorophenylhydrazine HCl synthesis

Yield:1166990-89-1 42%

Reaction Conditions:

Stage #1: 3-bromo-4-fluoroanilinewith hydrogenchloride;sodium nitrite in water at 0;
Stage #2: with tin(II) chloride dihdyrate in water at 0 - 20; for 19.5 h;

Steps:

140.a

A solution of sodium nitrite (4.2 g , 60 mmol) was added drop-wise to a mixture of 3-bromo-4-fluoroaniline (11.2 g, 58.9 mmol) and concentrated HCl (30 mL, 0.36 M) at 0 ⁰C over 30 min. The resulting clear solution was stirred for 45 min, and a solution of SnCl₂*2H₂O (27 g, 120 mmol) in concentrated HCl (30 mL) was added drop-wise at 0 ⁰C over 1.5 h. The mixture was stirred for 18 h at room temperature. The resulting precipitate was collected by filtration and crystallized from ethanol to provide the title compound (6.2 g, 42 %) as a yellow powder: ¹H NMR (300 MHz, DMSO-J₆) δ 10.24 (s, 3H), 8.42 (s, IH), 7.36-7.30 (m, 2H), 7.03-6.98 (m, IH).

References:

WO2009/89482,2009,A1 Location in patent:Page/Page column 241