12AX7 - 2-3-2008 at 15:59
Covering keto-acids last week in O. Chem II, I read that alpha-keto protons are around pKa ~ 17 and around 9 for beta-diketo molecules. So I figure,
what about a beta-triketo molecule? That would be something like, 3-acetyl-2,4-pentadione...
Tim
smuv - 2-3-2008 at 20:21
pka 8.6 in dmso
Arnett J. Am. Chem. Soc. 1984, 106, 6759
P.S. A useful tool
[Edited on 2-3-2008 by smuv]
chemrox - 2-3-2008 at 20:58
nice contribution guy!
12AX7 - 3-3-2008 at 04:40
Hmm interesting! Not as low as I expected, but the others are higher...maybe the textbook's values were in H2O?
Tim
Nicodem - 3-3-2008 at 04:59
The pKa values for water as solvent are:
Acetone (MeCOMe) ~20
Acetylacetone ( (MeCO)<sub>2</sub>CH<sub>2</sub> ) 8.95
Diacetylacetone ( (MeCO)<sub>3</sub>CH ) 6
Pearson, R. G.; Dillon, R. L. J. Am. Chem. Soc., 75 (1953) 2439.
(according to http://research.chem.psu.edu/brpgroup/pKa_compilation.pdf)
Diacetylacetone in water decomposes rapidly in presence of bases (to acetylacetone and acetate).
The much stronger C-H acids are some nitro compounds, for example dinitromethane has the pKa 3.6.