Carbon dioxide activation

C.l. Carbon monoxide and carbon dioxide activation assisted by... 

A. Behr, Carbon Dioxide Activation by Metal Complexes, VCH, Weinheim, 1988. 

In recent years there has been a growing interest in the chemistry of carbon dioxide, stimulated by current anxieties about alternative petrochemical feedstocks. One aspect under active exploration involves carbon dioxide activation via coordination to a transition metal, and indeed transition metal ions do form C02 complexes.177 The number of simple and reasonably stable complexes is still relatively small and usually limited to low oxidation state metal ions. There are many systems where C02 is used as a reagent giving rise to systems which, while not true C02 complexes, may simplistically be viewed as the products of insertion into metal-ligand bonds, e.g. reaction (9), where if L = H, formates are produced if L = OH, carbonates or bicarbonates result L = NR2 yields dialkylcarbamates and if L = R, carboxylate products result. Much of this area has recently been reviewed and will not be considered further.149... 

Braunstein P, Matt D, Nobel D (1988) Carbon-dioxide activation and catalytic lactone synthesis by telomerization of butadiene and C02. J Am Chem Soc 110 3207-3212... 

Figure A. Adsorption isotherms for the carbon dioxide/activated carbon system. Reproduced with permission from Ref. 33. Copyright 1972, Chemical Society of Japan.

Mortlock, R. P., R. C. Valentine, and R. S. Wolfe Carbon dioxide activation in the pyruvate clastic system of Clostridium butyricum. J. Biol. Chem. 234, 1653-1656 (1959). 

Animal and bacterial enzymes that utilize or synthesize carbamyl phosphate have activity with acetyl phosphate. Acyl phosphatase hydrolyzes both substrates, and maybe involved in the specific dynamic action of proteins. Ornithine and aspartic transcarbamylases also synthesize acetylornithine and acetyl aspartate. Finally, bacterial carbamate kinase and animal carbamyl phosphate synthetase utilize acetyl phosphate as well as carbamyl phosphate in the synthesis of adenosine triphosphate. The synthesis of acetyl phosphate and of formyl phosphate by carbamyl phosphate synthetases is described. The mechanism of carbon dioxide activation by animal carbamyl phosphate synthetase is reviewed on the basis of the findings concerning acetate and formate activation. 

Morris AJ, McGibbon RT, Bocarsly AB. Electrocatalytic carbon dioxide activation the rate-determining step of pyridinium-catalyzed CO2 reduction. ChemSusChem. 2011 4 191-6. 

To activate carbon dioxide for chemical reactions, it is advantageous to fix and destabilize this rather inert molecule. An important strategy to control and influence the reactivity of CO2 is its coordination to amines, metal-bound imido moieties, or metal centers (144), which leads to a decrease of the CO bond order, while the molecule in most cases becomes considerably bent. In biochemical pathways, the CO2 adduct of the coenzyme biotin (17) is involved in various carboxylation and transcarboxylation reactions (146). Similar structural motifs could become important functional building blocks for bioinspired photoreactions involving carbon dioxide activation steps (Fig. 18). 

Fig. 18. Ligand architectures for coordinative carbon dioxide activation structure of the biotin-C02 coenzyme (17) involved in many biological carboxylations (146). Proposed pyridinium-COz adduct (18) accelerating electrocatalytic carbon dioxide reduction processes (147).

Eghbali and Li have recently reported a highly efficient method for the conversion of carbon dioxide to cyclic carbonates in water (Figure 3.14). The organic base l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was used as a simple carbon dioxide activator at a level of 0.1-0.3 equivalents per mole of alkene. The reaction is catalysed by a catalytic amount of bromine provided by tetra-butylammonium bromide (TBAB) or sodium bromide. During the course of... 

Textural characterisation of activated carbons obtained from poly(ethylene terephthalate) by carbon dioxide activation... 

Munoz-Guillena MJ, Illan-Gomez MJ, Martin-Martinez JM, Linares-Solano A et al (1992) Activated carbons from Spanish coals. 1. Two-stage carbon dioxide activation. Energy Fuels 6(1) 9-15... 

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