(178q) Estimation of Enthalpies of Formation of Biomolecules as Potential Biofuel Components: Comparison of Group Contribution and G3(MP2) Methods

Interest in renewable energy sources has increased greatly in the past decade due to concerns about climate change and the cost of energy as well as national security interests in developing domestic energy sources. Biofuels offer an attractive alternative to fossil fuels as they offer a sustainable source of hydrocarbons, many of which are not competitive as food-stocks. Although several viable routes from biological materials to logistic fuels exist, there are a great number of potential biofeedstocks that are not presently used.

We have examined the heats of formation and heats of combustion of a variety of novel biologically derived molecules which may be viable biofuels, specifically as components of biodiesel. Traditionally, estimating heats of formation was only possible via one of a series of group contribution methods. However, for molecules dissimilar to those from the data set used to develop the group contribution theory parameters, these predictions were not always adequate. Modern computational capabilities and algorithms have allowed calculation of these gas-phase heats of formations from quantum chemical calculations combine with statistical mechanics. Such calculations do not suffer from the dependence on the training set as do group contribution methods, and as such can be applied more readily to newly synthesized or proposed compounds. In this study we compare estimates of the heats of formation for potential biofuels components from both group contribution methods and quantum chemical calculation methods (G3(MP2)) and compare both with available experimental results.