Water → 5-Chloro-2-picolinic acid

Participants

Reaction Steps

0.10 g (0.5 mmol) of 2-trimethylsilylethynyl-5-chloropyridine, 0.01 g of sodium lauryl sulphate and 2 ml of deionized water are placed under an inert gas atmosphere. Subsequently, 0.25 g (15 mmol) of potassium permanganate is added thereto at 23° while stirring. After 2 hours the reaction mixture is treated with aqueous sodium bisulphite solution (about 40 percent) until, after filtration of a sample over filter paper, the violet colour of the permanganate has disappeared. The suspension is filtered over a layer of Dicalite and the filtrate is adjusted to pH 3 with 1N aqueous hydrochloric acid, whereby a white suspension results. This is cooled in an ice bath and the crystals are filtered off. The crystals are treated with 1 ml of deionized water, the suspension is again cooled to 0° and the crystals are filtered off. These are evaporated twice from methanol/toluene under reduced pressure and the residue is dried in a high vacuum. There are obtained 17 mg of 5-chloropyridine-2-carboxylic acid as a white, solid residue, m.p. 171°-172°.

Provenance & Evidence