Reaction of CO2 with

The reaction of CO2 with allene using bis(dicyciohexylphosphino)ethane as a ligand affords a mixture of esters of methacrylic acid 17 and crotonic acid 18, and the lactone 19[12],... 

GirhotolAmine Process. This process developed by the Girdler Corporation is similar in operation to the alkali carbonate processes. However, it uses aqueous solutions of an ethanolamine, ie, either mono-, di-, or triethanolamine. The operation of the Girbotol process depends on the reversible nature of the reaction of CO2 with monoetbanolamine [141-43-5] to form monoethanolamine carbonate [21829-52-7]. 

Fig.l. QoCbvarious solvents in the reaction of CO2 with GMA using Aliquat... 

Figure 19. (a) Cluster size dependence of the rate constants for the reactions of CO2 with the large hydrated hydroxyl anions at T= 130 K O, experimental values for OH (H2O), —, calculated values for 0H (H20)n. (b) Dependence of rate constants on cluster size for the reactions of 0H (H20)n with SO2 at T = 135 K. Taken with permission from ref. 19. 

The reaction of Co2+ with ROOH limits initiation. In the quasistationary regime, the rate constants of formation and decomposition of hydroperoxide given by the following equations ... 

The reaction of CO2 with 1,3-butadienes in the presence of Ni catalysts usually gave an isomeric mixture of carboxylic acids 89 and 90 after hydrolysis (Scheme 32).47,48 The oxa-7r-allylnickel complexes 87 and 88 might be the reaction intermediates, which could be formed through oxidative cyclization of Ni(0) with C02 and the dienes. When Me2Zn was used as a transmetallation agent to react with the oxa-7r-allylnickel intermediates under a C02 atmosphere, further carboxylation took place at the 7r-allylnickel unit. Thus, the 1,4-diesters 95 were obtained after acidic hydrolysis and treatment with diazomethane as shown in Scheme 32.47... 

Equations 1 to 3 show some of fixation reactions of carbon dioxide. Equations la and lb present coupling reactions of CO2 with diene, triene, and alkyne affording lactone and similar molecules [2], in a process catalyzed by low valent transition metal compounds such as nickel(O) and palladium(O) complexes. Another interesting CO2 fixation reaction is copolymerization of CO2 and epoxide yielding polycarbonate (equation 2). This reaction is catalyzed by aluminum porphyrin and zinc diphenoxide [3],... 

Both CO2 activation and enolate formation are combined in the preparation of malonic acid derivatives. The reaction of CO2 with methacrylic esters or methacry-lonitrile and under visible light irradiation produced the corresponding aluminum porphyrin malonate complex. When diethylzinc was added to this system, Al(TPP)Et could be regenerated by axial ligand exchange reactions, and the malonic acid derivatives were formed catalytically with respect to the aluminum porphyrins in a one-pot photosynthetic route (Scheme 1). The first step in this... 

Table 1 lists some of the binding constants and rate constants measured for the reaction of CO2 with redox-active molecules. Various techniques have been used to measure these constants including cyclic voltammetry, pulsed radiolysis, and bulk electrolysis followed by UV-visible spectral measurements. The binding constants span an enormous range from less than 1 to 10 M [13-17]. Co(I) and Ni(I) macrocyclic complexes have been studied in some detail [13-16]. For the cobalt complexes, the CO2 binding constants K) and second-order rate constants for CO2 binding (kf) are largely determined by the Co(II/I) reduction potentials... 

These first two steps, electron transfer and CO2 binding, are also common to Fe, Co, and Ni macrocychc complexes. For these catalysts, one-electron reductions corresponding to Fe(I/0) [37-40], Fe(II/I) [41], Co(II/I) [42-44], and Ni(II/I) [45] couples are followed by reaction with CO2. However, for these catalytic systems, which operate at much more negative potentials than the Pd complexes, the ratedetermining step is not the reaction of CO2 with the reduced metal species. This reaction is very rapid. As shown in Table 1, the rate of reaction of Cod)(rac-Me6[14]4,ll-diene) with CO2 is 1.7 x 10 [14]. 

Diomides. These compds are the dibasic acid derivs of ammonia or amines, and contain two -CONH2 groups. Numerous combinations of diacids, diamines, and amino acids have been interacted. Copolymers contg various proportions of two or more diacids have been prepd (Ref 2). The diamide of carbonic acid is called urea, H2NCONH2. It is a product of animal metabolism and is prepd industrially by reaction of CO2 with excess NH3 at high temp, or by an older method involving the hydrolysis of cyanamide (Ref 5)... 

The reaction of CO2 with phenol has been studied using a number of photo-catalysts. It was found that 2-hydroxybenzoic acid and catechol were the main products and some selectivity was achieved by judicious choice of the photo-catalyst.71... 

Various unsaturated compounds, such as CO2, isocyanates and aldehydes, undergo Pd-catalysed cycloaddition with vinyl epoxides. Reaction of CO2 with 127 affords cyclic carbonates 128 with retention of the configuration at C(3), offering a method of cis hydroxylation of epoxides [66], and has been used for the synthesis of the side-chain unsaturated (—)-exo-brevicomin (129) [67], The tetrahydrofuran 131 was prepared by [3+2] cycloaddition of activated alkenes such as benzylidene malononitrile (130) with vinyl epoxide via Michael addition and allylation [68],... 

Reaction of CO2 with ethanolamines Kinetics from gas-absorption, Chem. Eng. Sci 1981, 36, 479-482. 

Considerable heat is evolved in the reaction of CO2 with Ascarite II a U tube that has absorbed a considerable amount of CO2 should be allowed to cool for about 15 min before it is weighed. 

Estimation of Process Involved in the Evolution Reaction of CO2 with the Aid of VCTIES. Curve 1 in Figure 6.4 realizes the polarogram at the interface between... 

REACTIONS OF CO2 WITH HYDROGEN AND FURTHER REACTION COMPONENTS... 

Green and co-workerii described the reaction of CO2 with Cp4MejAli M02 (281]. An MoC(0)OAJ system was formed via the insertion of carbon dioxide into an Mo-Al bond. Hydrolysis, extraction with hydrobromic acid, and the addition of aqueous hexafluoruphosphale yielded the carbonyl derivative lCp Mo(CO)Br]PF6, and the reaction of MoCpjHfMgBrCTHF) ] with CO2 yielded MoCpj(CO) (282,283]. 

The reaction of CO2 with Ni(PChx3)3 or [Ni(PChx3)2]2N2 in toluene at RT yields Ni(CO2XPChx3)2 0.75(C7Hg) as red-orange crystals that are air stable for a few hours. This complex has also been prepared by carrying out the reaction in liquid CO2. Other phosphines, Ni(C02)L2, are formed via Ni(C02)L3 species... 

The second method of recovery is also predicated on the reaction of CO2 with base. However, in this method the bases most often used are ethanolamine, ethylenediamine, phenethylamine, or hyamine hydroxide... 

In 1997, Baiker and coworkers reported that RuCl2(dppe)2 is an excellent catalyst for the reaction of CO2 with H2 and HN(CH3)2 to give DMF, with a TON and TOF of 740 000 and 360 000 h , respectively (Eq. 11.75) [139]. Changing the CO2 pressure from 85 atm to 18 atm reduced the activity from 360 000 h to 150 000 h . The authors claimed that this result indicates that supercritical conditions may not be necessary for high catalytic activity. 

Kinetic studies of the reaction of CO2 with radical anions generated from dialkyl fumarates and maleates showed that C-C bond formation was the rate-determining step. The pseudo first-order rate constants, kco2, for fumarate radical anions in C02-saturated DMF were found to vary between 0.35 and 1.5 s and to decrease in the same order as observed for dimerization [218]. Rate constants for maleates (kco2 varied from 32.0 s to 18.0 s ) were higher. Rather slow is the coupling of CO2 with the 4-keto isophorone in MeCN (k co2 = 0-35 s ) [219]. 

The dark reaction, known as the Calvin cycle, uses the reducing power of NADPH as well as the free energy stored in the ATP to assimilate carbon dioxide in the form of carbohydrates. The way by which Nature achieves carbon fixation is via the reaction of CO2 with ribulosebiphosphate (RuBP) to give two molecules of 3-phosphoglycerate, a process which is catalyzed by the enzyme RuBP-carboxylase. The phosphogylcerate is converted further to fructose 6-phosphate, the final product of the Calvin cycle. The overall reaction, despite its complex mechanism, corresponds to the simple Eq. (16) above. 

It should be noted that reactions (1) and (2) represent the sum of many intermediate reactions. These include the photosynthetic fixation of CO2 as biomass, the secretion of organic and carbonic acids by roots and associated microflora, the decomposition of litter and soil organic matter to form soil CO2, the reaction of CO2 with water to form carbonic acid, the reaction of organic and carbonic acids with calcium and magnesium silicates, and the formation of dissolved calcium, magnesium, and bicarbonate in soil and groundwater. 

Carbonic anhydrase is an enzyme of central importance to the production of gastric acid. This enzyme, which contains zinc, accelerates the naturally occurring reversible reaction of CO2 with water. Before considering the mechanism of action of the enzyme, note the resonating structure of CO2. The carbon-to-oxygen bonds are polar the molecular structure can be represented by the resonance hybrids shown in Figure 2.54. Note that in two of the three forms shown the central carbon atom has a positive charge. 

The reaction of CO2 with 1,3-butadiene leads to the formation of 2-ethylidene-5-hepten-4-olide (126) in low yields (equation 157) 587.588 oligomers of butadiene are the major products. 

Polar, aprotic solvents such as DMF were necessary for the formation of (126). [Pd(diphos)2] (104) gave the best performance as catalyst. Using [Pd(DBA)2] (105) as palladium source, a number of mono- and bi-dentate nitrogen, phosphorus and arsenic ligands were investigated and Me2PCH2CH2PMe2 was found to be nearly as efiective as diphos. The reaction of CO2 with a bis(i7 -allyl) complex of palladium was believed to be a key step in the process (equation 158). 

Sharma (S35), including the use of organic solvents (such as toluene, xylene, diethylene glycol, and polyethylene glycol) for the measurement of a and by the chemical method. In each case, the reaction between CO2 and selected amines is employed to determine a. For example, values of interfacial areas obtained in a reaction of CO2 with cyclohexylamine in xylene plus 10% isopropanol, in a 10-cm-i.d. column packed with 0.5 in. ceramic Raschig rings, are reported in Fig. 15. A comparison with the values for aqueous systems shows a 50% improvement attributable to the lower surface tension of xylene ([Pg.74]

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