Protonation of conjugated carbonyl groups in sulfuric acid solutions. III. α,β-Unsaturated ketosteroids

Abstract

Protonation of 20 a,a-unsaturated ketosteroids by sulfuric acid was studied by ultraviolet spectrophotometry. Plots of log [B]/[BH+] from spectral data against the amide acidity function, HA, gave straight lines with unit slope. The pKDH+ values thus obtained show the same additive effects of substiti~ents as that reported previously for simple a,a-unsaturated alicyclic ketones.

The basicity of enones. Substituent effects and the correlation of protonation with HA

“…This result is consistent with previous studies on cyclopentenones and cyclohexenones. 4 It is striking that protonation of 3-alkenones follows Ha so closely throughout such a broad range of acidity. This requires that the /b//bh+ ratio for the protonation of a Measured using a standard spectrophotometric method.7…”

Kinetic acidity function Hc.thermod.. 2. The scale in perchloric acid

“…C is formally about 50 from the figures given above, but in principle infinitely large, i.e., if the rate profiles are precisely parallel.…”