3,4,5,6-Tetrachloro-2-cyanobenzoic acid ammonium salt synthesis

Yield:-

Reaction Conditions:

with ammonia;water in xylene at -4 - 85; for 6 h;Product distribution / selectivity;

Steps:

1.b; 5; 6

352 gm of TCPC solution obtained in step 1 (a) in the form of organic (xylene) layer was added drop by drop in a three necked round bottom flask containing 633 gm 25% liquor ammonia at molar ratio Jj9. Maintained at a temperature of 4.8°C. The flask was placed in an ice bath containing brine solution at temperature between -2°C to -4°C. The reaction mixture was allowed to stand for 60 minutes in the cold bath. The temperature was periodically checked to ensure that the temperature of the reaction mixture did not exceed 5⁰C. Then the flask was removed from the bath and the temperature was slowly raised up to 50⁰C in 1 hour time. The flask was further gradually heated to 85°C and stirred at this temperature for 4 hours. A hazy reaction mass was obtained. This mass was filtered in a Buchner funnel containing filter paper. Wet cake obtained was washed with 200 ml xylene. Xylene washed cake was dissolved in hot water at 80⁰C to form a clear solution; to this solution, 100 ml of xylene was added. The reaction solution was stirred for 30 minutes at 80⁰C and phase separation was seen in the flask in which the organic layer was at the top. Xylene layer was sent for recycling and the aqueous layer was transferred to an ice bath at 5⁰C. Ammonium salt of TCCBA were precipitated as white shiny crystals. These crystals were separated by filtration. 286 gm of ammonium salt of TCCBA was obtained. This material was dried in tray dryer at 100⁰C for 8 hours.; Example 5; The process was carried out as per the Example 1 upto step (a). On step (b), 1 liter of ethyl alcohol was used as organic solvent instead of dimethyl formamide (DMF). The resultant white crystals of TCCMB was 205 gm having purity 95.0% having melting point of 84.5°C was obtained. The HCB content was measured on gas chromatogram and was found to be 7 ppm.; Example 6; The process was carried out as per the Example 1 upto step (a). On step (b), 1 liter of methyl alcohol was used as organic solvent instead of dimethyl formamide (DMF). The resultant white crystals of TCCMB was 204 gm having purity 96.0% having melting point of 84.6°C was obtained. The HCB content was measured on gas chromatogram and was found to be 6 ppm.

References:

WO2008/96371,2008,A1 Location in patent:Page/Page column 13-16