6-amyl-α-pyrone (6PP) is a fermentation derived unsaturated lactone having considerable potential to be developed as a platform chemical. Due to the presence of different functional moities in the ring and position of the double bond attached with the ring, different reactions can be performed giving useful chemicals. For instance, ring-opening (RO) and decarboxylation of 6PP in water yielded non-2-en-4-one (1) (Fig 1a) with 95% conversion and nearly 60% selectivity at 498 K, without using any catalyst. The activation barrier was calculated to be 180 kJ/mol in presence of water using DFT, which compares well with the experimental apparent activation barrier of 166 kJ/mol. The selectivity of decarboxylated product was further enhanced using acidic silica-alumina and γ-alumina giving around 65% selectivity and 75% conversion at a reduced temperature of 463 K. The measured apparent activation energy for γ-alumina ( 99 kJ/mol) was comparable to the DFT calculated intrinsic endothermicity of the proton transfer step 98 kJ/mol (Fig 1b), which was essential for obtaining the ring-opened intermediate. The hydrogenation of non-2-en-4-one over Pd/C catalyst was further experimented to yield 4-nonanone (3) which can served as solvent or intermediate for other reactions. In order to produce longer chain hydrocarbons of diesel and jet fuel ranged fuels, mixed oxide (CaO-MgO) was synthesized and utilized as a catalyst for the C-C coupling reaction via aldol condensation reaction. The condensation of nonanone with furfural and 5-hydroxymethyl furfural (HMF) over CaO-MgO yielded upto 40% (5) and 60% (4) of the branched aldol products at 443 and 393 K (Fig 1a), which may further hydrogenated to give liquid transportation fuel.

Valorization of biomass derived lactones into fuels and chemicals

254th National Meeting (2017)

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