METHOD FOR PREPARING TETRACHLOROPICOLINIC ACID Russian patent published in 2006 - IPC C07D213/79 C07D213/84 C07D213/61 

FIELD: chemical technology.

SUBSTANCE: method for preparing tetrachloropicolinic acid involves interaction of 2-cyanopyridine and chlorine in liquid phase in the melt at temperature 120-200°C under pressure up to 0.6 MPa in the presence of catalysts wherein phosphorus chlorides and oxychlorides are used in the mole ratio of 2-cyanopyridine to catalyst = 1:(0.1-1.0) followed by dissolving the reaction mixture in inert solvent, addition of water at temperature 70-80°C, decomposition of phosphorus chlorides at increased temperature to yield hydrogen chloride and phosphoric acid, separation of phosphoric acid from organic layer and the following addition of sulfuric acid to organic layer and hydrolysis of residue by heating the mixture to 120-140°C. Method provides increasing yield and purity of the end product, simplifying technology, reducing cost for its preparing.

EFFECT: improved preparing method.

2 cl, 5 ex