2,5-Dimethylfuran is a cyclic ether derived from sugar that has several attractive features as a potential biofuel. It has an energy density 40% higher than ethanol [1]. Because it does not blend with water, pipeline transport is viable. Its fuel characteristics, including a higher octane and cetane rating, also allow it to be combusted in a virtually unmodified engine. An existing infrastructure of glucose isomerase transformation for the food and beverage industry would allow many potential sugar feedstocks to be converted into 2,5-dimethylfuran. More studies need to investigate its toxicity, but it is thought to be comparable to gasoline, since it is a metabolite of hexane [2]. Further oxidation of 2,5-dimethylfuran into 2,5-furandicarboxylate gives a suitable monomer for polymerization into plastics that could replace petroleum-derived polyethylene terephthalate (PETE) [3].

Researchers have developed a route to synthesize dimethylfuran from fructose or glucose using a combined biochemical and thermochemical approach. The process involves pretreatment of cellulose or starch with enzymes to yield glucose. Several microbes have been found to degrade cellulose, including Phanerochaete chrysosporium, Trichoderma reesei, Acetobacter xylinum and Fibrobacter succinogenes S85 [4,5,6]. Alternatively, thermochemical and/or acid treatment of cellulose can give 5-hydroxymethylfurfural (5-HMF) directly [7]. This and many other thermochemical and enzymatic methods of treating biomass are covered elsewhere. Glucose isomerase can convert the glucose into fructose, which is reductively dehydrated with hydrochloric acid and water, or chromium chloride in an ionic liquid into 5-HMF [8]. The yield from fructose is higher than from glucose when using acid hydrolysis, but recent research has demonstrated that chromium chloride in an ionic liquid adequately reduces both sugars. Otherwise, the high-yield isomerization of glucose to fructose could maintain a higher overall yield. 5-HMF is subsequently reduced to dimethylfuran by a copper-ruthenium catalyst [9]. Continuing developments in biomass pretreatment as well as thermochemical catalysis give potential routes other than shown below, and the references provide more information.

The following is a 2,5-Dimethylfuran pathway map. For the biological pathway, organisms which carry out the pathway are given above, but other organisms may also carry out this biochemistry. Follow the links for more information on compounds or reactions.

[1] Román-Leshkov Y, Barrett CJ, Liu ZY, Dumesic JA. , 2007. Nature, Jun 21;447(7147):982-5.
[2] Iwata M, Takeuchi Y, Hisanaga N, Ono Y. Int Arch Occup Environ Health. 1983;53(1):1-8.
[3] Storbeck, R; Ballauff, M. Polymer (1993), 34(23), 5003-6
[4] Keller FA, Hamilton JE, Nguyen QA. Appl Biochem Biotechnol. 2003, 105-108:27-41.
[5] Bibollet X, Bosc N, Matulova M, Delort AM, Gaudet G, Forano E. J Biotechnol. 2000 Jan 28;77(1):37-47.
[6] Ilmén M, Saloheimo A, Onnela ML, Penttilä ME. Appl Environ Microbiol. 1997 Apr;63(4):1298-306.
[7] Srokol Z, Bouche AG, van Estrik A, Strik RC, Maschmeyer T, Peters JA. Carbohydr Res. 2004. Jul 12;339(10):1717-26
[8] Zhao H, Holladay JE, Brown H, Zhang ZC. Science. 2007, Jun 15;316(5831):1597-600.
[9] Schmidt LD, Dauenhauer PJ., 2007, Nature, Jun 21;447(7147):914-5.