Thiophene-3-carboxylic acid → 4-Ethyl-2-propyl-1-(3-thenoyl) semicarbazide

Temperature

5 °C

A stirred solution of 2.62 g (20.5 mmol) of thiophene-3-carboxylic acid and 2.8 mL (20.0 mmol) of triethylamine in 20 mL of THF was cooled to 5° C. and 2.6 mL (20.0 mmol) of isobutyl chloroformate was added dropwise over 5 minutes. The mixture was stirred at 5° C. for 5 minutes and added to a suspension of the 4-ethyl-2-propyl semicarbazide prepared above in 20 mL of THF at 5° C. This mixture was allowed to warm to room temperature and stirred overnight. The mixture was concentrated to remove most of the solvent, taken up in 75 mL of water and extracted with two 100 mL portions of ethyl acetate. The combined ethyl acetate extracts were washed with 50 mL of 5% aqueous HCl and 50 mL of saturated aqueous sodium bicarbonate (NaHCO3), and dried over MgSO4. Removal of the solvent left 5.30 g of crude 4 -ethyl-2-propyl-1-(3-thenoyl) semicarbazide as an oil.

1. temperatureto warm to room temperature
2. stirringstirred overnight
3. concentrationThe mixture was concentrated
4. customto remove most of the solvent
5. extractionextracted with two 100 mL portions of ethyl acetate
6. washThe combined ethyl acetate extracts were washed with 50 mL of 5% aqueous HCl and 50 mL of saturated aqueous sodium bicarbonate (NaHCO3)
7. dry with materialdried over MgSO4
8. customRemoval of the solvent
9. waitleft 5.30 g of crude 4 -ethyl-2-propyl-1-(3-thenoyl) semicarbazide as an oil

ORD record

ord-3788da22400547588000d5e5ed67015c

Source dataset

uspto-grants-1994_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05334726