Revealing Reaction Mechanisms by Combining Raman Spectroscopy and Quantum Chemistry
Using Raman spectroscopy and density functional methods, an experimental and theoretical research team at Argonne National Laboratory led by Dr. Christopher L. Marshall have identified the molecular intermediates and reaction mechanisms during the polymerization of furfuryl alcohol (ChemCatChem, Cover story, September 19, 2011, vol. 3, issue 9, 1451-1458). Furfuryl alcohol, which is derived from biomass, is a sustainable building block for polymeric materials and alternative fuels.[1-7] Polymerization of furfuryl alcohol in acidic media has been proposed by several research groups.[8-14] However, the current work is the first to distinguish the controversial intermediate species (dienes and diketones) using a combination of Raman spectroscopy and theoretical calculations. A strong aliphatic C=C band observed in both the calculated and measured Raman spectra provides crucial evidence for understanding the polymerization reaction. It is confirmed that the formation of a conjugated diene structure rather than a diketone structure is involved in the furfuryl alcohol polymerization reaction. By combining experimental and theoretical investigations we can provide a more detailed molecular understanding of polymerization during the conversion of biomass to alternative fuels and industrial chemicals.
This work was supported as part of the Institute for Atom-efficient Chemical Transformations (IACT), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.
The cover picture shows furfuryl alcohol polymerization, an important reaction during the mineral acid treatment in aqueous solution. The identities of molecular intermediates and reaction mechanisms during the polymerization were investigated by Raman spectroscopy and density functional theory calculations. Detailed thermochemistry of protonation of furfuryl alcohol, initiation of polymerization, and formation of conjugated dienes and diketonic species were predicted using computational methods. In the Full Paper on p. 1451 ff., Taejin Kim, Rajeev S. Assary et al. report that a strong aliphatic CC band in the measured and calculated Raman spectra support the formation of conjugated diene structure, as a result of acid catalyzed furfuryl alcohol polymerization, compared to diketone structure. This combined experimental and theoretical investigation provides a detailed molecular understanding of polymerization during the conversion of biomass to platform chemicals for alternative fuels and industrial chemicals. The initials IACT stand for the Institute for Atom-efficient Chemical Transformations, an Energy Frontier Research Center funded by the U.S. Department of Energy.