Chapter 6 Study Guide: The Proton Transfer Reaction
Reading: Chapter 6
Objectives:
You should be able to:
 Identify the acid, base, conjugate acid, and conjugate base in a proton transfer (PT) reaction
 Draw proper curved arrows for the mechanism of a PT reaction.
 Say whether the Keq is >1, 0, or <1 for a reaction – (reactants or products favored)
 Determine whether an acid is stronger or weaker when you are given pKa values (or using the
pKa values you were asked to memorize).
 Determine whether a given acid and base will not react, will react "completely", or will be at
equilibrium. If the reaction is at equilibrium, will the products or reactants be favored? (and
therefore will the Keq be >1, 0, or <1?). (this is for reactions where pKa values are given or they
are the compounds for which you were asked to memorize pKa values).
 Determine the strongest base (or strongest acid) that can exist in a specific solvent, or whether a
particular reagent would react with the solvent in a PT reaction instead of performing the
desired reaction. (Leveling effect)
 Determine how changes in the reaction conditions will affect the equilibrium ala Le Chatlier's
principle.
 Relate entropy and enthalpy to Gibbs free energy
 Interpret and draw free energy diagrams for reactions - be able to label them as
endergonic/exergonic, label transition states, transition state energies (energy of activation),
and ∆G for the reaction.
 Determine which acid is more acidic/which base is more basic qualitatively (without pKa data),
by examining the four factors (in priority order): Charge, Atom (electronegativity, size, and
orbital type), Resonance/Aromaticity, and Induction. (you might need to review the standard
patterns for resonance from earlier)
 Utilize the qualitative rules above to determine which proton on a compound is most acidic or
which site is most basic on a compound.
 Determine whether nearby groups are electron donating or electron-withdrawing and whether
that stabilizes or destabilizes a base (- charged site).
 Determine whether nearby groups are electron donating or electron-withdrawing and whether
that stabilizes or destabilizes a carbocation or other positively charged site.