Pyridine → Pyridin-3-yl [2-(2,6-dichloroanilino)phenyl]acetate

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Reaction Steps

This salt is stirred under nitrogen and anhydrous conditions for 1 hour with 6.5 ml of pyridine and 1.5 g of [o-(2,6-dichloro-anilino)-phenyl]-acetic acid at 20°-30°C and the mixture is then evaporated in vacuo at a maximum temperature of 40°C. The residue is dissolved in 50 ml of ether and while cooling with ice, washed with saturated potassium hydrogen carbonate solution, 1 N-hydrochloric acid, and with ice water. The bulk of the [o-(2,6-dichloro-anilino)-phenyl]-acetic acid-3-pyridyl ester remains in the ether layer and, after this latter has been dried with magnesium sulphate and evaporated in vacuo, is obtained therefrom as a pale brown oil which crystallises on trituration. The new ester contains as impurity 1-(2,6-dichloro-phenyl)-2-hydroxy-indole from which it can be separated by being dissolved in ether/petroleum ether 1:1 and filtered through a silica gel column. The [o-(2,6-dichloro-anilino)-phenyl]-acetic acid-3-pyridyl ester is obtained from the filtered ether/petroleum ether solution (evaporation in vacuo) in the form of colourless crystals which, after precipitation with petroleum ether from an ethereal solution, melt at 84°-86°C.

Provenance & Evidence