  We study the exclusive decays of $B$ meson into pseudoscalar charmonium
states $\eta_c$ and $\eta_c^\prime$ within the QCD factorization approach and
find that the nonfactorizable corrections to naive factorization are infrared
safe at leading-twist order. The spectator interactions arising from the kaon
twist-3 effects are formally power-suppressed but chirally and logarithmically
enhanced. The theoretical decay rates are too small to accommodate the
experimental data. On the other hand, we compare the theoretical calculations
for $J/\psi, \psi^\prime$, and $\eta_c, \eta_c^\prime$, and find that the
predicted relative decay rates of these four states are approximately
compatible with experimental data.
