A study of the infrared spectra of 1, 4-thiapyrone, its hydrochloride, 3-carboxy-1, 4- thiapyrone, the corresponding ester and the amide, shows no evidence for normal carbonyl absorption. The spectrum of 1, 4-thiapyrone hydrochloride is shifted toward lower frequencies compared to the thiapyrone itself. These results are in agreement with numerous other lines of evidence in indicating that the thiapyrone nucleus, and the ...
