2-FLUORO-4,N-DIHYDROXY-BENZAMIDINE synthesis

Yield:880874-38-4 82%

Reaction Conditions:

with hydroxylamine in methanol;water at 20; for 3 h;Heating / reflux;

Steps:

1

At room temperature, 139 g (2.1 mol) of 50% hydroxylamine aqueous solution was added dropwise to a methanol solution of 144.0 g (1.05 mol) of 2-fluoro-4-cyanophenol. Temperature of the reaction system was gradually increased and stirred under reflux for 3 hours. After the reaction, this was ice-cooled, and cool water was added to the reaction system to effect precipitation of crystals. The thus obtained crystals were collected by filtration and dried to obtain 139.5 g of (1-A) (yield 82%).A 8.1 ml (0.1 mol) portion of pyridine was added at room temperature to 300 ml of N,N-dimethylacetamide containing 17 g (0.1 mol) of (1-A), and 6.7 g (33 mmol) of phthaloyl dichloride was added thereto in portions. After the addition, this was stirred at room temperature for 30 minutes and then the reaction temperature was increased to 100°C. This was stirred as such for 3 hours and then spontaneously cooled. Since crystals were precipitated when methanol was added thereto, they were collected by filtration. By drying the thus collected crystals, 36 g (yield 83%) of (1-B) was obtained.At room temperature, 8.7 ml (50 mmol) of N,N-diisopropylethylamine was added to 300 ml of N,N-dimethylacetamide solution of 8.7 g (20 mmol) of (1-B), and 9.6 g (50 mmol) of octyl chloro formate was added dropwise thereto. A 14 g portion of potassium carbonate was added thereto and stirred as such at room temperature for 3 hours. After adding tetrahydrofuran, separation by filtration was carried out, and methanol was added to the resulting filtrate to effect precipitation of crystals. The crystals were collected by filtration and dried, dispersed in methanol, heated and then filtered to obtain 13.4 g of the illustration compound (1) (yield 90%).Phase transition temperature of the thus obtained illustration compound (1) was measured by DSC measurement and texture observation under a polarization microscope, thereby obtaining the following results: Cry to SmC at 133 C, SmC to Nb at 159 C and Nb to Iso at 194 C.

References:

WO2007/11003,2007,A1 Location in patent:Page/Page column 25-26