2-methyl-1-propanol

Isobutanol (IUPAC nomenclature: 2-methylpropan-1-ol) is an organic compound with the formula (CH3)2CHCH2OH (sometimes represented as i-BuOH). This colorless, flammable liquid with a characteristic smell is mainly used as a solvent. Its isomers, the other butanols, include n-butanol, 2-butanol, and tert-butanol, all of which are important industrially. Isobutanol (IUPAC nomenclature: 2-methylpropan-1-ol) is an organic compound with the formula (CH3)2CHCH2OH (sometimes represented as i-BuOH). This colorless, flammable liquid with a characteristic smell is mainly used as a solvent. Its isomers, the other butanols, include n-butanol, 2-butanol, and tert-butanol, all of which are important industrially. Isobutanol is produced by the carbonylation of propylene. Two methods are practiced industrially, hydroformylation is more common and generates a mixture of isobutyraldehydes, which are hydrogenated to the alcohols and then separated. Reppe carbonylation is also practiced. Higher-chain alcohols have energy densities close to gasoline, are not as volatile or corrosive as ethanol, and do not readily absorb water. Furthermore, branched-chain alcohols, such as isobutanol, have higher-octane numbers, resulting in less knocking in engines. Although produced naturally during the fermentation of carbohydrates and may also be a byproduct of the decay process of organic matter, Isobutanol or C5 alcohols have never been produced from a renewable source with yields high enough to make them viable as a gasoline substitute before the 2008 Nature article that produced over 20g/L isobutanol from glucose in E.coli. To modify an organism to produce these compounds usually results in toxicity in the cell. This difficulty was bypassed by leveraging the native metabolic networks in E. coli but altered its intracellular chemistry using genetic engineering to produce these alcohols. Key pathways in E. coli were modified to produce several higher-chain alcohols from glucose, including isobutanol, 1-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol, and 2-phenylethanol. This strategy exploits the E. coli host's highly active amino acid biosynthetic pathway by shifting part of it to alcohol production. It is proposed that these unusual alcohols can be produced as efficiently as the biosynthesis of ethanol. Escherichia coli Escherichia coli, or E. coli, is a Gram-negative, rod-shaped bacteria. E. coli is the microorganism most likely to move on to commercial production of isobutanol. In its engineered form E. coli produces the highest yields of isobutanol of any microorganism. Methods such as elementary mode analysis have been used to improve the metabolic efficiency of E. coli so that larger quantities of isobutanol may be produced. E. coli is an ideal isobutanol bio-synthesizer for several reasons: The primary drawback of E. coli is that it is susceptible to bacteriophages when being grown. This susceptibility could potentially shut down entire bioreactors. Furthermore, the native reaction pathway for isobutanol in E. coli functions optimally at a limited concentration of isobutanol in the cell. To reduce the sensitivity of E. coli in high concentrations, mutants of the enzymes involved in synthesis can be generated by random mutagenesis. By chance, some mutants may prove to be more tolerant of isobutanol which will enhance the overall yield of the synthesis. Clostridium While cellulosic biomass like corn stover and switchgrass is abundant and cheap, it is much more difficult to utilize than corn and sugar cane. This is due in large part because of recalcitrance, or a plant's natural defenses to being chemically dismantled. Adding to the complexity is the fact biofuel production that involves several steps—pretreatment, enzyme treatment and fermentation—is more costly than a method that combines biomass utilization and the fermentation of sugars to biofuel into a single process.