Abscisic acid is a hormone that can cause plants to lose their leaves, a process known as abscission.
Proton
1.1 Rank acid strength
1.2 $pK_a$
$H_A$
1
4.75
$H_B$
2
-1.74
$H_C$
4
9.9
$H_D$
3
4.75
$H_E$
5
10
1.1 Rank the protons labelled A-E in terms of the acidity, from 1-5: Strongest acid=1/Weakest acid=5
1.2 From the $pK_a$ table provided from Klein, estimate the $pK_a$ of the protons labelled A-E to one decimal place, e.g. $pK_a$=3.2
1.3 Draw the corresponding bases and justify your ranking in the space below. Include any resonances structures.
1.4 Using a quantitative argument based on $pK_a$ values, which proton A-E can the $NH_3$ base deprotonate? The $pK_a$ of $NH_4^+$ is 9.2.
1.5 Identify the Lewis acid sites on this molecule with a $\delta^+$. Circle the Lewis basic sites (or draw the lone pairs at the Lewis basic sites)
