Potassium thiocyanate → 5-Thiocyanatopyridine-2-carboxylic acid methyl ester

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Reaction Steps

To the solution of 28.3 g of 5-aminopyridine-2-carboxylic acid methyl ester in 80 ml of 20% sulfuric acid, cooled to -4°, the solution of 14.31 g of sodium nitrite in 30 ml of water is added dropwise while stirring and maintaining the temperature below 0°. Thereafter the mixture is stirred for 15 minutes below 0° and the mixture of 28 g of potassium thiocyanate and 8 g of cuprous thiocyanate is added portionwise to said solution. Each addition causes evolution of gas and a black oil to separate. With continued stirring the oil again dissolves and the solution is stirred for 3 hours. It is extracted with methylene chloride, the extract filtered and evaporated, to yield the 5-thiocyanatopyridine-2-carboxylic acid methyl ester.

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