2-(4-Chlorophenoxy)propionic acid → 5-[1-(4-Chlorophenoxy)ethyl]-1,3,4-thiadiazol-2-amine

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Reaction Steps

Into a 100 milliliter, 3-neck flask adapted with a Claisen adaptor, paddle stirrer, thermometer, an addition funnel and condensor, was charged with 10.0 grams (0.050 mole) of 2-(4-chlorophenoxy)propanoic acid, (4.6 grams, 0.050 mole) of thiosemicarbazide and 30 ml. of dioxane. The slurry was heated to 90 degrees centigrade and the addition funnel was charged with phosphorous oxychloride (POCl3). The POCl3 (8.4 gram, 0.055 mole) was slowly added (for 30 minutes) while maintaining the temperature within 85-90 degrees centigrade. The resulting mixture was refluxed for 75 minutes and stood at ambient temperature for 16 hours. The flask was evacuated by using a water aspirator to remove volatiles (HCl, POCl3 and some dioxane) at sixty degrees centigrade and then the solution was cooled. Fifty (50) milliliters of water was added and 50 percent solution of NaOH was also added until the pH of the solution was 10; a solid precipitate formed. The solid precipitate was filtered off, washed with water, then dried in a vacuum oven at 70 degrees centigrade to white crystals which were recrystallized from the minimum amount of H2O/ethanol mixture, filtered and then dried in a vacuum oven at 80 degrees centigrade to white crystals of 5-[1-(4-chlorophenoxy) ethyl]-2-amino-1,3,4-thiadiazole. (Melting point 162-166 degrees centigrade).

Provenance & Evidence