Carbon dioxide, electrochemical fixation

The difficulty to transform CO2 into other organic compounds lies in its high thermodynamic stability. Typical activation energies for the dissociation and recombination ofC02 are of 535 and 13 kJ/mol, respectively [5], The activation can occur by photochemical or electrochemical processes, by catalytic fixation or by metal-ligand insertion mechanisms. As documented in different reviews, organometallic compounds, metallo-enzyme sites and well defined metallic surfaces are able to activate carbon dioxide [6-16],... 

Source Reprinted from I. Nakabayashi, F. Ushizaki, and K. Uosaki, A Photoelectrochemical Carbon Dioxide Fixation Spontaneous Up-Quality Conversion of Organic Compounds, in Environmental Aspects of Electrochemistry and Photoelectrochemistry, M. Tomkiewicz, H. Yoneyama, R. Haynes, and Y, Hori, eds. proceedings vol. 93-18, p. 49, Table 1, 1993. Reproduced by permission of the Electrochemical Society, Inc.)... 

Fig. 15.22. Electrochemical behaviors of p-type photoex-cited semiconductors and Mg electrodes in C02-satu-rated acetonitrile solution with 50 mM of benzyl chloride. (Reprinted from H. Ueda, K. Nakabayashi, Z. Ushizaki, and K. Uosaki, A Photoelectrochemical Fixation of Carbon Dioxide. Spontaneous Up Quality Conversion of Organic Compound, Cherrt. Lett. 190 1748, Fig. 2, 1993. Reproduced with permission of The Chemical Society of Japan.)...

Electrochemical activation of carbon dioxide has been performed in [Bmim][BF4] (Figure 6.5). This is probably very efficient because of the excellent solubility of carbon dioxide in this RTIL, and this led to very mild conditions for the activation—only 1 atm pressure was needed This contrasts significantly with many other carbon dioxide fixations that have been reported. Additionally, no catalyst was required and the RTIL was recyclable. The scope for electrochemical reduction and fixation of carbon dioxide in RTILS is exciting and more results in this area are expected soon. 

A recent addition to the field of functional, catalytic ionic liquids comes in the area of carbon dioxide fixation. However, in this example, the reaction was performed under solvent free conditions and the ionic liquid was just used as a catalyst. Using [Bmim][OH], yields of up to 58% were obtained for the synthesis of disubstituted ureas from amines and carbon dioxide.By considering the electrochemical reduction of carbon dioxide discussed above, it is clear that ionic liquids could have an important role to play in the area of carbon dioxide fixation. 

The electrochemical incorporation of CO2 into perfluoroalkyl derivatives has been explored in the case of (perfluoroalkyl)alkyl iodides and (perfluoroalkyl)alkenes, with an electrochemical system based on the use of consumable anodes combined with organometallic catalysis by nickel complexes. Iodide derivatives have been functionalized to the corresponding carboxylic acids by reductive carboxylation. Interesting and new results have been obtained from the fixation of CO2 into perfluoroalkyl olefins. Good yields of carboxylic acids could be reached by a carefull control of the reaction conditions and of the nature of the catalytic system. The main carboxylic acids are derived from the incorporation of carbon dioxide with a double bond migration and loss of one fluorine atom from the CF2 in a position of the double bond. 

Carbon Dioxide Fixation Low-valent rhenium complexes are effective in the catalytic reduction of carbon dioxide. The conversion can be accomplished photolytically or electrochemically and is of interest with regard to fuel production and greenhouse gas remediation [9]. Electrocatalytic reduction of CO to CO is initiated by the reduction of fac-Re(bpy)(CO)3Cl or a related complex and can be accomplished in homogeneous solution [54, 55] or on a polymer-modified electrode surface [56]. Catalytic current... 

Electrochemical Fixation of Carbon Dioxide (Cathodic Reduction in the Presence of Carbon Dioxide)... 

Among the two electrochemical fixation of carbon dioxide in organic molecules, this entry focuses on electrochemical fixation of carbon dioxide with C-C bond formation giving carboxylic acid. 

Platinum, grassy carbon, graphite, stainless steel, carbon fiber, silver, lead, mercury pool, and some other metals are reported to be usable as cathode materials in electrochemical carboxylation. Among them, platinum, stainless steel, carbon fiber, and graphite are frequently used for an efficient formation of carboxylic acid by electrochemical fixation of carbon dioxide with a sacrificial anode, such as magnesium and aluminum [1-4], as a couple in an undivided cell (one-compartment cell). 

Efficient fixation of carbon dioxide in various kinds of organic molecules has been successfully carried out by electrochemical method with C-C... 

Electrochemical Fixation of Carbon Dioxide (Cathodic Reduction in the Presence of Carbon Dioxide), Scheme 4 Synthetic Routes to NSAIDs having 2-Arylpropanoic Acid Skeletons by Electrochemical Carboxylation... 

One of great synthetic applications of electrochemical fixation of carbon dioxide is synthesis of 2-arylpropanoic acids, nonsteroidal anti-inflammatory drugs (NSAlDs), and their derivatives. Electrochemical carboxylations of benzyl halides [1, 3, 8-13], aryl methyl ketones [14, 15], and a-bromostyrenes [16] are reported to be successfully applied to the synthesis of several NSAIDs, such as ibuprofen and naproxen, and their precursors and derivatives (Scheme 4). 

Especially, syntheses of fluorinated analogues of NSAIDs (Schemes 5 and 6) by electrochemical fixation of carbon dioxide [11-13] indicate usefulness, significance, advantage, and convenience of electrochemical method because the syntheses by using fixation of carbon dioxide seem to be difficult by the conventional chemical methods. 

Use of supercritical carbon dioxide [21] as both a reagent and a solvent and ionic liquid as a solvent [22,23] for the electrochemical fixation of carbon dioxide is still under development and would also be one of future directions in this area. 

Zhang K, Wang H, Zhao S, Niu D, Lu J (2009) Asymmetric electrochemical carboxylation of prochiral acetophenone an efficient route to optically active atrolactic acid via selective fixation of carbon dioxide. J Elctroanal Chem 630 35-41... 

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