Hydrogen Sulfide → 3-Amino-2-cyano-3-ethoxypropenethioamide

Participants

Reaction Steps

A mixture of 51.2 g of 3-amino-3-ethoxy-2-cyano-2-propenenitrile (above) and 37.8 g of triethylamine in 200 ml of pyridine was continuously stirred and heated to 70° while 60 g of gaseous hydrogen sulfide was bubbled in during 1.5 hours. Heating was continued at 65°-70° for 0.5 hour. Thin-layer chromatographic analysis indicated that no reaction had occurred. The mixture was heated overnight at 55° but still no reaction had occurred. An additional 150 ml of pyridine was added and the mixture was heated to 75°-80° while 17 g of hydrogen sulfide was bubbled in during 0.5 hour. Thin-layer chromatographic analysis indicated that a reaction had occurred, but was incomplete. An additional 18 g of hydrogen sulfide was added during 1 hour at 75°-80°; thin-layer chromatography indicated that the reaction was completed. The reaction mixture was evaporated to dryness under reduced pressure. The residue was recrystallized from ethanol to give a first crop of 28 g of 3-amino-2-cyano-3-ethoxypropenethioamide; m.p. 170°-171°. A second crop of 15 g of this product (m.p. 169°-171°) was obtained by diluting the mother liquor with ice-water. A small sample of crop I was recrystallized again from ethanol (charcoal) to give an analytical sample; m.p. 180°-181°. A total of 43.0 g of 3-amino-2-cyano-3-ethoxypropenethioamide was obtained. The nmr spectrum was consistent with the assigned structure.

Provenance & Evidence