In this paper we focus on the relation between the propensity of a molecular crystal to undergo chemical reactions after impact or shock and energy transfer rates. When a crystal receives a shock, low-frequency lattice vibrations (called phonons) are excited. Typical phonon frequencies are 0-200 cm(-1). This energy must then be converted to bond stretch frequencies (1000-2000 cm(-1)) before bond breaking can occur. We derive a simple formula for the total energy transfer rate into a given vibron band in terms of the density of vibrational states and the vibron-phonon coupling. We are able to estimate the phonon upconversion rate in widely varying energetic materials such as TATB, HMX, and Pb styphnate by examining existing inelastic neutron scattering data. We find that the estimated energy transfer rates in pure unreacted material are several times greater for the sensitive explosives studied than the insensitive explosives.