Accurate bond dissociation energies (BDEs) are foundational for characterizing combustion chemistry, particularly pyrolysis. To properly describe the multi-configurational nature of bond-breaking, we calculate these BDEs to chemical accuracy using multireference correlated wavefunction methods. We compare the strengths and weaknesses of the multireference singles and doubles configuration interaction (MRSDCI) and several size-extensive variants, including flavors of the multireference averaged coupled pair functional method (MRACPF, MRACPF2). Insights into BDE trends based on ester size are analyzed for methyl formate through methyl crotonate. We find that the carbonyl group has only a local effect on BDEs and C-C double bonds in ester alkyl chain increase the strengths of non-terminal bonds adjacent to the double bond except those that produce an allylic radical. The trends are easily explained as resulting from geometric relaxations and/or resonance stabilization. Finally, we assess the implications of these trends for biodiesel combustion.

Biodiesel thermochemistry from multi-reference correlated wavefunction calculations

245th National Meeting (2013)

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