78-83-1 Isobutanol

Institute of Biochemical Engineering, University of Stuttgart, Stuttgart, Germany 

2 The Access Code for the Microbial Production of Branched-Chain Alcohols 2-Ketoacid Decarboxylase and an Alcohol Dehydrogenase 

3 Metabolic Engineering Strategies for Directed Production of Isobutanol 

The future society and petrochemical-based industry are faced to energy and resource limitation and environmental problems due to the steadily decreasing availability of fossil fuels. Besides hydro-, wind-, and solar power, the biotechnological production of fuels and chemicals from renewable resources is regarded as key technology to 

Bioprocessing of Renewable Resources to Commodity Bioproducts, First Edition. Edited by Virendra S. Bisaria and Akihiko Kondo. 

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Isobutyl alcohol, isobutanol, 2-methyl-propanol, isopropyl carbinol, Me2CHCH20H. B.p. 108°C. Occurs in fusel-oil. Oxidized by potassium permanganate to 2-methyl-propanoic acid dehydrated by strong sulphuric acid to 2-methylpropene. 

The propylene-based chemicals, n- and isobutanol and 2-ethyl-1-hexanol [104-76-7] (2-EH) dominate the product spectmm. These chemicals represent 71% of the world s total oxo chemical capacity. In much of the developed world, plasticizers (qv), long based on 2-EH, are more often and more frequendy higher molecular weight, less volatile Cg, and C q alcohols such as isononyl alcohol, from dimerized normal butenes isodecanol, from propylene trimer and 2-propyl-1-heptanol, from / -butenes and aldol addition. Because of the competition from the higher molecular weight plasticizer alcohols,... 

Packed Tubes Cocurrent flow of immiscible hquids through a packed tube produces a one-stage contact, characteristic of hne mixers. For flow of isobutanol-water through a 0.5-in diameter tube packed with 6 in of 3-mm glass beads, Leacock and Churchill [Am. Jn.st. Chem. Eng. J., 7, 196 (1961)] find... 

Oxygenates and Chemicals A whole host of oxygenated products, i.e., fuels, fuel additives, and chemicals, can be produced from synthesis gas. These include such produc ts as methanol, ethylene, isobutanol, dimethyl ether, dimethyl carbonate, and many other hydrocarbons and oxyhydrocarbons. Typical oxygenate-producing reactions are ... 

Modification of urea-formaldehyde resins with other reagents gives rise to a number of useful materials. For example, co-condensation of urea-formaldehyde and a monohydric alcohol in the presence of small quantities of an acidic catalyst will involve simultaneous etherification and resinification. n-Propanol, n-butanol and isobutanol are commonly used for this purpose. As an example n-butanol will react with the methylol urea as shown in Figure 24.4. 

One class of materials with some inherent PSA properties includes polyvinyl-ethers. Vinyl ether monomers are industrially derived from the reaction of acetylene with alcohols [117]. The most common alcohols used are methanol, ethanol or isobutanol. A generic structure of the vinyl ether is shown below ... 

A mixture of methanol and butanol or isobutanol in water with a ratio of 4 4 22 in the grafting process produces a higher graft yield than a mixture of butanol or isobutanol in water with a ratio of 8 22. 

Partial replacement of ethanol by methanol has nearly no effect. In the case of propanol an increase in grafting is visible. This can be attributed to the mixing of higher carbon alcohols, e.g., butanol and isobutanol, with the active solvent methanol, which increases the miscibility of the monomer in these grafting systems and, consequently, increases the penetration of monomer to the active sites on the cellulose chains. 

White-rot fungus has been used as a biocatalyst for reduction and alkylation. The reaction of aromatic -keto nitriles with the white-rot fungus Curvularia lunata CECT 2130 in the presence of alcohols afforded alkylation-reduction reaction [291]. Alcohols such as ethanol, propanol, butanol, and isobutanol could be used (Figure 8.39d). 

Experiments were carried out using isotopically labelled methanol (97% 0) and ethanol (98% purchased from MSD Isotopes. Anhydrous isobutanol was purchased from Aldrich Chemical Co., Inc. and contained the natural abimdances of orygen isotopes, i.e. 99.8% and 0.2% O. Nafion-H was obtained fi om C. G. Processing, Inc. and Amberlyst resins were provided by Rohm and Haas. The 2SM-5 zeolite was provided by Mobil Research Development Corp. H-Mordenite, montmorillonite K-10, and silica-alumina 980 were obtained firom Norton, Aldrich, and Davison, respectively. y-AIumina was prepared from Catapal-B fi om Vista. 

A wide variety of soUd acid catalysts has been examined using the methanol/isobutanol reaction mixture to establish activity and selectivity patterns for alcohol coupling and dehydration reactions (Table 1). 

Percent isotopic composition ( 2 mol%) of O-containing products formed over the Amberlyst-35 catalyst (03 g) from the reaction of 0-methanol (or 0-ethanol) with 0-isobutanol at 110°C, 1 MPa, and GHSV = 14300 /kg catal/hr. 

Stuq>e Selective Reactions of Methanol/Isobutanol Mixtures... 

The probe reaction utilized a 1/1 molar mixture of methanol and isobutanol over H-mordenite, a strongly acidic zeolite comprised of linear one-dimensional channels made up of 12-ring 6.5 by 7.0 A windows [8]. There is a side-pocket system in H-... 

The results in Table 3 show that H-mordenite has a high selectivity and activity for dehydration of methanol to dimethylether. At 150°C, 1.66 mol/kg catal/hr or 95% of the methanol had been converted to dimethylether. This rate is consistent with that foimd by Bandiera and Naccache [10] for dehydration of methanol only over H-mordenite, 1.4 mol/kg catal/hr, when extrt lat to 150°C. At the same time, only 0.076 mol/kg catal/hr or 4% of the isobutanol present has been converted. In contrast, over the HZSM-5 zeolite, both methanol and isobutanol are converted. In fact, at 175 X, isobutanol conversion was higher than methanol conversion over HZSM-5. This presents a seemingly paradoxical case of shape selectivity. H-Mordenite, the zeolite with the larger channels, selectively dehydrates the smaller alcohol in the 1/1 methanol/ isobutanol mixture. HZSM-5, with smaller diameter pores, shows no such selectivity. In the absence of methanol, under the same conditions at 15(fC, isobutanol reacted over H-mordenite at the rate of 0.13 mol/kg catal/hr, higher than in the presence of methanol, but still far less than over H M-5 or other catalysts in this study. 

Space time yields of products formed over H-mordenite and HZSM-5 from a methanol/isobutanol = 1/1 reactant mixture (1.72 mol/kg catal/hr of each) at 0.1 MPa. 

Figure 1. Molecular graphics representations of [A] S 2 attack of a methanol molecule on a methyl oxonium ion in the side-pocket of the mordenite structure and [B] the size limitation of the bulky isobutanol molecule that prevents it from turning in the main channel to react with the methyl oxonium ion in the side-pocket.

Ad(ii) On catalysts with pores and cavities of molecular dimensions, exemplified by mordenite and ZSM-5, shape selectivity provides constraints of the transition state on the S 2 path in either preventing axial attack as that of methyl oxonium by isobutanol in mordenite that has to "turn the comer" when switching the direction of fli t through the main channel to the perpendicular attack of methyl oxonium in the side-pocket, or singling out a selective approach from several possible ones as in the chiral inversion in ethanol/2-pentanol coupling in HZSM-5 (14). Both of these types of spatial constraints result in superior selectivities to similar reactions in solutions. 

Conclusive evidence has been presented that surface-catalyzed coupling of alcohols to ethers proceeds predominantly the S 2 pathway, in which product composition, oxygen retention, and chiral inversion is controlled 1 "competitive double parkir of reactant alcohols or by transition state shape selectivity. These two features afforded by the use of solid add catalysts result in selectivities that are superior to solution reactions. High resolution XPS data demonstrate that Brpnsted add centers activate the alcohols for ether synthesis over sulfonic add resins, and the reaction conditions in zeolites indicate that Brpnsted adds are active centers therein, too. Two different shape-selectivity effects on the alcohol coupling pathway were observed herein transition-state constraint in HZSM-5 and reactant approach constraint in H-mordenite. None of these effects is a molecular sieving of the reactant molecules in the main zeolite channels, as both methanol and isobutanol have dimensions smaller than the main channel diameters in ZSM-S and mordenite. 

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