Process for producing 2,3,5-trichloropyridine
AssigneeCiba-Geigy Corporation
InventorsHansjakob Fah, Alfred Grieder
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Abstract
Production of 2,3,5-trichloropyridine by reacting 3,5-dichloro-2-pyridone at 30.degree. to 150.degree. with phosgene in the presence of an N,N-disubstituted formamide of the formula ##STR1## in which R.sub.1 and R.sub.2 can be identical or different and are each an alkyl group having 1 to 4 carbon atoms, or R.sub.1 and R.sub.2 together with the nitrogen atom form the pyrrolidino, piperidino or morpholino, and in the presence of an inert solvent. 2,3,5-trichloropyridine is a valuable intermediate for producing herbicidally active .alpha.-[4-(3',5'-dichloropyrid-2-yloxy)-phenoxy]-alkanecarboxylic acids and derivatives thereof.
Claims1
A process for producing 2,3,5-trichloro-pyridine which comprises suspending in a mixture of toluene and water, 3,5-dichloro-pyridone, the water present is separated by azeotropic distillation, adding 0.05-0.15 mol of N,N-dimethylformamide per mol of 3,5-dichloro-2-pyridone introducing, 1.0-1.3 mols of phosgene per mol of 3,5-dichloro-2-pyridone at 75.degree.-80.degree. C., stirring the reaction mixture further for 1 hour, reacting the excess phosgene with aqueous ammonia, separating the phases, and obtaining from the organic phase, after removal of the solvent by distillation, the formed 2,3,5-trichloro-pyridine in the form of a melt.
Dependencies are inferred from the claim text.