Talk:Verkade base

Conflicting pKa values as of the two cited sources

The first cited source https://doi.org/10.1002/047084289X.rn00702.pub2 states a pKa of 32.9 in CH3CN, as is what the article states. This is contradicted by the second source https://doi.org/10.1002/zaac.19895780109, which states a pKa of 16 (it did not specify the solvent, but from later sections it can be seen that they have successfully prepared it from t-BuOK in CH3CN, hence it would be unlikely that it would be as high as 32.9 even in CH3CN). The latter value of 16 does make more intuitive sense considering the general nature of protonated phosphorus species, but nonetheless demands clearing up of the subject. Also both sources stated that it is a solid (albeit low melting as noted by the first source) rather than an oil, and one is not sure if such also demands revision. Pygos (talk) 11:33, 18 March 2026 (UTC)

Potentially good catch. Why does the ZaaC paper indicate pKa near 16? Maybe this preparative eq worries you:

R₃PH]Cl + KOtBu → R₃P + KCl + HOtBu

and you think that HOtBu has a pKa in the teens? Provisos:

• The ZaaC paper is a preparative route, not equilibrium measurement.
• The ZaaC report is by Verkade, the inventor and presumably world's expert on these things. He wrote the EROS report with the high pKa.
• The pKa of tBuOH is sky high in MeCN. Things go wacko outside of water. Not very technical terms, I realize.

Those are some considerations.--Smokefoot (talk) 13:28, 18 March 2026 (UTC)