Chapter 3, Problem 68P

Recall from section 1.10B that there is restricted rotation around carbon-carbon double

bonds. Maleic acid and fumaric acid are two isomers with vasity different physical properties and $\text{p}{K}_{\text{a}}$ values for loss of both protons. Explain why each of these differences occurs.

maleic acid fumaric acid

$\begin{array}{ccc}\text{mp}\left({}^{\text{ο}}\text{C}\right)& 130& \\ \text{solubility}\left(\text{g/L}\right){\text{in H}}_{\text{2}}{\text{O at 25}}^{\text{ο}}\text{C}& 788& \\ \text{p}{K}_{{\text{a}}_{\text{1}}}& 1.9& \\ \text{p}{K}_{{\text{a}}_2}& 6.5& \end{array}$ $\begin{array}{c}286\\ 7\\ 3.0\\ 4.5\end{array}$