Chemistry Reference
In-Depth Information
According to Appendix 1, the pK
a
value for a carboxylic acid is approximately 4.75.
Furthermore, if we imagine converting the carboxylic acid to an ester, we recognize
that protons adjacent to esters have pKa values of approximately 25-30. Finally,
the pK
a
value for a proton adjacent to a nitrile is approximately 20-25. Using
the formula described in Problem 7, we calculate a pK
a
value of approximately
11.25-13.75 for the protons between the two functional groups. Therefore, the
order of deprotonation is as follows:
According to Appendix 1, the pK
a
value for an amide is approximately
15-17, the pK
a
of a primary alcohol is approximately 15-16, and the pK
a
of a
proton adjacent to an amide is approximately 30-35. Therefore, the order of depro-
tonation is as follows:
According to Appendix 1, the pK
a
value for an acetylene is approximately 25, and the pK
a
of a vinyl proton is approximately 35-40. While the acetylene and olefin lend delocaliza-
tion effects to adjacent anions, the absence of heteroatoms incorporated in these functional
groups minimizes this effect, and the pK
a
at this position will resemble something between
avinylpK
a
and a hydrocarbon pK
a
. Therefore, the order of deprotonation is as follows:
