Reactions of Carbon Dioxide

A comprehensive review of the catalysis of the Cope and Claisen rearrangements includes catalysis by transition metal complexes.  

Methyl (R)-3-oxo-7-(methoxycarbonyloxy)-8-nonenoate (47) undergoes intramolecular allylation catalysed by Pd(OAc)2/P2He to give racemic cyclohexanone derivative (48) but similar cyclization of the sodium salt of (47) gives an optically active producti . 

The isomerisation of trans-stilbene to its cis form is catalysed by (Cu(CH3CN)ij 1+/LL systems (LL = 2,2 -bipyridyl, o -phenanthroline and derivatives) upon irradiation with visible light ( 390 nm)i . Copper(I) trifluoromethane sulphonate catalyses photobicyclisation of myrcene to afford 6,6-dimethyl-2-methylenebicyclo[3.2.0]heptanel 3 and of ethyl N, N-diallycarbamates to afford bicyclic pyrrolidinesi .  

Acetylenes are metathesised by Mo(VI) alkylidyne complexes ligated by electron-withdrawing ligands eg 

Reactions of Carbon Dioxide.— The interaction of carbon dioxide with transition-metal complexes has been reviewed. Reaction of cmrbon dioxide with [TiCNMea) and 1,2-epoxycyclohexane followed by hydrolysis gives 2-hydroxy- 

CO2 with [Pd -CHaC(Me)CH2 OAc]g-PCy3 in benzene gives predominantly (58), in addition to 2-ethylidenehepta-4,6-dienoic acids. In contrast, in DMF with [Pd(dppe)2] the five-membered lactone (59) is formed. PdCla in the presence of base (e.g. KHCO3) catalyses reaction (22). 1  

A text and the proceedings of a conference describe catalytic applications of transition-metal compounds in organic synthesis. New developments in nickel-catalysed carbon-carbon bond formation and the coupling of alkyl groups using transition-metal catalysts have also been reviewed. [TiGp2Cl2] catalyses reaction (23) (n = 1 or 2, X = Mg) carbonylation of the product followed by hydrolysis gives y- or 5-lactones (i.e. X = CO).  

Perego, and V. Tartiari, Inorg. Chim. Acta, 1978, 28, LI47. 

Sugita, and Y. Takezaki, Chem. Letters, 1977, 1495. 

Examples of C02 insertion into M-H and M-C bonds are numerous. Less common are instances of carbon dioxide insertion into M-O and M-N bonds. There are excellent reviews which encompass these areas by Eisenberg and Hendriksen (4), Volpin and Kolomnikov (24), Kolomnikov and Grigoryan (25), and Sneeden (26). Hence we will emphasize developments since the time of these reviews (i.e., from 1979 to present) with our perspective being primarily that of understanding mechanistic aspects of these insertion processes. Some overlap with these earlier reviews will necessarily occur during such efforts. 

In principle the insertion of C02 into a transition metal hydrogen bond can result in either M-0 or M-C bond formation, i.e., production of metalloformate (4) or metallocarboxylic acid (5) derivatives. Thus far, 

C02 to the metal center directly parallels that of metal - olefin binding (36). For the olefin insertion reaction, activation parameters support a concerted reaction process as depicted above with a relatively low enthalpy of activation, i.e., simultaneous bond breaking and bond making, and a negative activation entropy (37). Thus far, no studies determining the corresponding activation parameters for the C02 insertion process have been reported. 

This variance in intimate mechanisms is likely seen in the reactions of HCr(CO)5 and HW(CO)j with C02 to provide HC02M(C0)j derivatives (45). For example, carbon monoxide dissociation in the chromium anion, as evinced by l3CO exchange studies, occurs at a rate indistinguishable by conventional techniques from that of C02 insertion. Consistent with this observation, the rate of decarboxylation of HC02Cr(CO)jis retarded in an atmosphere of carbon monoxide. Similar behavior was noted in decarboxy- 

It is worthwhile to note that in the reaction of the group 6B metal hexacarbonyls with the azide anion to provide isocyanatometallates, a concerted mechanism is proposed based on kinetic parameters which involves a three-centered transition state (7), and that the activation enthalpy is some 22.6 kJ lower for tungsten than for chromium (52). This reactivity sequence correlates with an increase in M-CO bond distances going from chromium to tungsten hexacarbonyl (53-55). 

There appeared several reports treating the activating effect of carbon dioxide on the dimerization or telomerization of butadiene, as described before. But in none of these reactions did carbon dioxide behave as a reactant. Sasaki, Inoue, and Hashimoto found that carbon dioxide was incorporated to a small extent into the dimer of butadiene (103). 

The reaction carried out at 120°C in DMF using a palladium catalyst coordinated by bis(diphenylphosphino)-1,2-ethane (39) produced 2-ethyl- 

The following mechanism was proposed for the reaction of carbon dioxide with butadiene  

The cobalt(I) compound K(THF)o,5 Co(Pr -salen) reacts with COj to give [Co(Pr -salen)(C02)K(THF)] which has structure (13.225). Recently, the complex [Mo(C02)2 (PMe3)4] containing two CO2 molecules was obtained. Based on spectroscopic studies, a tram structure with two / -C02 ligands was proposed.  

The iridium compound [IrCl(C8H,4)(PMe3)3] reacts with carbon dioxide to afford the complex (13.226). Coordinated CO2 undergoes migratory insertion to the 

The c7-carbyl complexes react similarly [see reactions (4.181 )-(4.186)]. The insertion of CO 2 into the M —O bond leads to the formation of metal carbonates. An analogous reaction involving the M —N bond in metal amide complexes affords carbamates. 

The reaction of CO2 with complexes containing M —N bonds may proceed according to the mechanisms (13.236) and (13.237). Carbon dioxide reacts with 1,3-dienes, 

Carbon dioxide reacts with 1-hexyne to give 4,6-dibutyl-2-pyrone in addition to tributylbenzenes [equation (13.239)]. A stoichiometric reaction of dienes with CO2 

Koinuma, Saishin No C Kagaku To Sono Cijutsu Ni Kansuru Koshukai Tekisuto, 1979, 22. 

Several syntheses involving the complexation of a Cr(CO 3 group to arenes to enhance and direct nucleophilic attack have been reported. In the presence of water and [Ru3(CO)ia], alkyl exchange between tertiary amines occurs [reaction (30)]. Reactions of the type (31) are catalysed by [Ru3(CO)i3] to 

Tamao and M. Kumada in Organometallic Reactions and Syntheses , ed. E. I. Becker and M. Tsutsui, Plenum, New York, 1980. 

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Only about 10% of the total urea production is used for amino resins, which thus appear to have a secure source of low cost raw material. Urea is made by the reaction of carbon dioxide and ammonia at high temperature and pressure to yield a mixture of urea and ammonium carbamate the latter is recycled. 

Morta.r, Mortar, principally slaked lime and sand, sets because of the evaporation of water, the deposition of calcium hydroxide, and the absorption of water by the bricks or cement blocks, foUowed by hardening as a result of the absorption and reaction of carbon dioxide. 

The ammonium carbamate then loses a molecule of water to produce urea [57-13-6] CO(NH2)2- Commercially, this is probably the most important reaction of carbon dioxide and it is used worldwide ia the production of urea (qv) for synthetic fertilizers and plastics (see Amino resins Carbamic acid). 

The naturally occurring compound urea, CO(NH,), was first synthesized by Friedrich Wohler in Germany in 1828 by heating ammonium cyanate. This synthesis was a significant event because it was the first time that an organic compound had been produced from an inorganic substance. Urea may also be made by the reaction of carbon dioxide and ammonia ... 

Acetic acid, CH,COOH(l), could be produced from (a) the reaction of methanol with carbon monoxide (b) the oxidation of ethanol (c) the reaction of carbon dioxide with... 

Urea, NH2CONH2, is the diamide of carbonic acid, (HO)2CO, and is manufactured in large volume for use in fertilizers and plastics by the reaction of carbon dioxide and ammonia. 

Sullivan, B. P, K. Krist, and H. E. Guard, Eds., Electrochemical and Electrocatalytic Reactions of Carbon Dioxide, Elsevier, Amsterdam, 1993. 

The reactions of carbon dioxide with zinc hydroxide complexes of the 3-t-butyl 5-methyl and 3,5-di-wo-propyl pyrazolyl derivatives were investigated. IR spectroscopy demonstrated formation of a bicarbonate derivative of the former complex and NMR showed a rapid reversible... 

Ito and co-workers observed the formation of zinc bound alkyl carbonates on reaction of carbon dioxide with tetraaza macrocycle zinc complexes in alcohol solvents.456 This reversible reaction was studied by NMR and IR, and proceeds by initial attack of a metal-bound alkoxide species. The metal-bound alkyl carbonate species can be converted into dialkyl carbonate. Spectroscopic studies suggested that some complexes showed monodentate alkyl carbonates, and varying the macrocycle gave a bidentate or bridging carbonate. Darensbourg isolated arylcarbonate compounds from zinc alkoxides as a by-product from work on polycarbonate formation catalysis.343... 

Zinc carbamate complexes are well known, and the structural types and stabilities can be compared with thiocarbamates and dithiocarbamates which are discussed in Sections 6.8.11.1.3 and 6.8.7.1.4482 Carbamates of zinc can be formed from the reaction of carbon dioxide with alkylzinc alkyl amides and further reaction with alkylzinc can give a distorted cubane structure.483 The tetrameric diethylcarbamate species initially formed can also be used to produce monomeric or dimeric carbamate structures in reaction with amines tetramethylethylenediamine forms a monomer [(Me2NCH2)2Zn(02CN(C2H5)2)2] with an octahedral zinc center and pyridine forms a dimer[CsH5NZn2Me(02CN(C2H5)2)3] with tetrahedral zinc centers.484... 

Stanton and Merz studied the reaction of carbon dioxide addition to zinc hydroxide, as a model for zinc metallo-enzyme human carbonic anhydrase IIJ 36. It was shown that the LDA calculations (DFT(SVWN)) were not reliable for locating transition state structures whereas the post-LDA ones (DFT(B88/P86)) led to the transition state structures and ener-... 

A reaction of carbon dioxide that is essential for life forms is that of photosynthesis in which C02 is converted by plants into glucose. The process can be summarized as... 

C02 Acceptor A fluidized bed coal gasification process in which the heat is provided by the exothermic reaction of carbon dioxide with calcium oxide. Developed by the Conoco Coal Development Company in the 1970s. 

Figure 5.2. Reactions of carbon dioxide and water, which illustrate its involvement in control of soil water pH.

The concept of employing three components, all of which contribute one carbon atom to the final allene unit (see Scheme 5.4), is illustrated in its purest form by the reaction of carbon dioxide (165) with 2 equiv. of an alkylidenetriphenylphosphorane 166, the process very likely involving the generation in the first step of a ketene intermediate 167, which subsequently reacts with further 166 to yield the allene product 168 (Scheme 5.25) [66]. 

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],... 

Miscellaneous Reactions.—A full report has appeared of the reactions of carbon dioxide and carbon disulphide with tervalent phosphorus aryl esters and amines the products are ureas and thioureas, respectively.74 The suggested mechanism, previously invoked for similar reactions of carboxylic acids, involves the N-phosphonium salt (97). 

Kolbe hydrocarbon synthesis orgchem The production of an alkane by the electrolysis of a water-soluble salt of a carboxylic acid. kol-bo. hT-dro kar-bon, sin-th3-s3s Kolbe-Schmitt synthesis org chem The reaction of carbon dioxide with sodium phenoxide at 125°C to give salicyclic acid. kol-bo shmit, sin-th3-s3s Konowaioff ruie phys chem An empirical rule which states that in the vapor over a liquid mixture there is a higher proportion of that component which, when added to the liquid, raises its vapor pressure, than of other components., k6-n9 va-lof, rul ... 

This enzyme [EC 4.2.1.1], also referred to as carbonate dehydratase, is a zinc-dependent enzyme that catalyzes the reaction of carbon dioxide with water to form carbonic acid (or, of bicarbonate and a proton). See also Proton Transfer in Aqueous Solution Manometric Assay Methods Marcus Rate Theory... 

Reaction of carbon dioxide with Af-[l-chloro-2,2,2-trifluoro-l-(trifluoromethyl)-ethyl]-A, A -dialkylformamidines has been described as a procedure to prepare 4-(diaLkylamino)-5(2f/)-oxazolones 51 (Scheme 7.13 Table 7.9, Fig. 7.10). Mechanistically, this reaction probably does not proceed via a nitrile ylide given the observed regioselectivities and the dependence of the reaction rate on the solvent. 

Carbon dioxide is one of the maj or global warming gases. The ocean acts as a reservoir for carbon dioxide and therefore will slow the effects of this gas on global warming. How is this air-water transfer rate dependent on the rate of reaction of carbon dioxide with liquid water to form H2CO3 ... 

Electrochemical Reactions of Carbon Dioxide 205 Tab. 1 CO2 binding constants and rates for selected redox-active compounds... 

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