Dehydrogenation of Alcohols
Publication Date: 2010-Oct-27
The IP.com Prior Art Database
The transformation of alcohols into the corresponding carbonyl compounds is one of the most frequently performed reactions in organic synthesis. An industrially used type of this transformation which is frequently utilized are so called "dehydrogenation" or "oxidative dehydrogenation" reactions. Both technologies are particularly useful for the synthesis of basic chemicals, such as of butyraldehyde and isobutyraldehyde, from an oil-based raw materials. We have investigated if state of the art dehydrogenation or oxidative dehydrogenation techniques can be applied to bio-based or fermentatively obtained alcohols like butanol or isobutanol. It was found that bio-butyraldehyde and bio-isobutyraldehyde could be efficiently used as starting materials for further transformations, e. g. the synthesis of polyvinylbutyrate or polyalcohols. The results were essentially the same in terms of yield, selectivity and quality. Drawbacks with respect to the use of bio-based raw materials compared to conventional petro-based materials were not observed. It is therefore possible to change from a petro-based to a bio-based material feedstock for the production of butyraldehydes and their derivatives, especially NPG and TMP, if petro-based materials should run short in the near future.
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Dehydrogenation of Alcohols
The transformation of alcohols into the corresponding carbonyl compounds is one of the most frequently performed reactions in organic synthesis. Traditionally, stoichiometric and even over-stoichiometric amounts of (co-)oxidants are used for these conversions. These procedures, which eventually generate copious quantities of heavy metal waste, are hardly compatible with environmental regulations. A number of metal-catalyzed methods have been described as interesting alternatives; this has introduced an industrially used type of this transformation which is often called '"dehydrogenation" or "oxidative dehydrogenation". Endothermic dehydrogenations deliver hydrogen as useful couple product, while oxidative dehydrogenations are performed in presence of air or oxygen to give water and hence, rendering these reactions exothermic (Scheme 1). Both technologies are particularly useful for the synthesis of basic chemicals (Industrial Organic Chemistry,
K. Weissermel, H.-J. Arpe, Wiley VCH, 2003).
R OH R O
R OH + +
R = H, alkyl, alkenyl, aryl
Scheme 1: (Oxidative) Dehydrogenations of Alcohols.
Dehydrogenation of primary C1-C5 alcohols can be performed in presence or absence of air or other oxidants in batch or preferably in continuous mode (US4816606). These transformations are known in gas and liquid phase, and homogenous and heterogeneous catalysts have been described. Fixed bed, fluidized bed, moving bed, micro tubular, tube-cluster or other reactors concepts can be applied to the reaction preferably around atmospheric pressure (JP59048429, JP60200832, US5149884, EP1125634, JP2006257001, FR2924362). Gas-phase dehydrogenations can be performed preferably with Cu-containing catalysts on various supports like alumina, silica, glas or metal oxides, preferably zinc and chromic oxide (JP70028761, JP73019611, JP74027271, JP59048429, US5204308, US5227530, EP1000658, WO2009144032, SU342115) preferably between 100 - 450 °C. Cu-catalysts with various incorporated elements (Ag, Al, Ca, Ce, Co, Cr, Fe, Mg, Mo, Ni, Pt, Rh, V, W, Zn) have been reported as (supported) vapour phase dehydrogenation catalysts (SU345115, US3875239, DE2627230, EP37149, US4590175, US5198592, JP3194051, JP07316089, EP1125633, US7314960, CN101530804). Additionally, NiO/MnO/MgO (US4304943), transition metal carbides and/or nitrides (DE10130896), mixed Pd-Bi compounds (WO2008006792), vandadium pentoxide (EP747123), microporous zeolithes on inorganic oxides
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(US20060264318) and bimetallic platinum group metal compounds (WO2009060019) have been described as catalysts for this transformation. Furthermore, various other catalysts (e.g zinc oxide) have been described for large scale industrial dehydrogenations and might be used for C1 - C5 alcohols (Handbook of Heterogenous Catalysis, G. Ertl, H. Knözinger, F. Schüth, J. Weitkamp (Eds.), Wiley VCH, 2008)
Various Ru and Os c...