Carboxylic acids carbon dioxide

Alkane Alcohol Aldehyde Carboxylic acid Carbon dioxide... 

In the poly carboxylic acids, carbon dioxide is the major product of radiolysis, but the carbon monoxide yields are greater than they are for the aliphatic carboxylic acids. However, the radical yields are not greater than expected on the basis of the model compounds, which suggests that excited states play an important role in the degradation of these poly acids. 

Alcohols Carboxylic acids Carbon dioxide Octa-9,12-dien-l-yl acetate... 

Carboxylic acids Carbon dioxide Formic acid Fumaric acid... 

CARBOXYLIC ACIDS Carbon dioxide. Chloroacetonitride. Difr) -Cyclopentadivinyl) (chloro)hydridozirconium. Dihalobis(triphenylphosphine)palladium(ll) complexes. CARDENOLIDES S-Methyl p-toluene thiosulfonate. 

An electrosynthetic procedure has been described for converting alkyl halides into the homologous carboxylic acids. Carbon dioxide... 

The adduct (31) formed from dialkyl sulphates and DMF is a potent esteri-fying agent for a range of carboxylic acids. Carbon dioxide-catalysed ester exchange has been described. Carboxylic acids react readily with diphenyl disulphide in the presence of triphenylphosphine to afford the corresponding phenyl thioesters. ... 

Carboxyl and nitrile groups are usually introduced in synthesis with commercial carboxylic acid derivatives, nitriles, or cyanide anion. Carbanions can be carboxylated with carbon dioxide (H.F. Ebel, 1970) or dialkyl carbonate (J. Schmidlin, 1957). 

Resorcinol carboxylation with carbon dioxide leads to a mixture of 2,4-dihydroxyben2oic acid [89-86-1] (26) and 2,6-dihydroxyben2oic acid [303-07-1] (27) (116). The condensation of resorcinol with chloroform under basic conditions, in the presence of cyclodextrins, leads exclusively to 2,4-dihydroxyben2aldehyde [95-01-2] (28) (117). Finally, the synthesis of l,3-bis(2-hydroxyethoxy)ben2ene [102-40-9] (29) has been described with ethylene glycol carbonate in basic medium (118), in the presence of phosphines (119). Ethylene oxide, instead of ethyl glycol carbonate, can also be used (120). 

An important extension of this carboxylation strategy has recently been suggested by Zhang and Young (1997) who studied the degradation of two polycyclic aromatic hydrocarbons (PAHs), naphthalene and phenanthrene, in a sulfate-reducing sediment. The naphthalene was found to be converted to 2-naphthoic acid and the phenanthrene to phenanthrene carboxylic acid (see below). Further degradation to C02 was rapid after the presumptive initial carboxylation. Possibly carbon dioxide derivatives can be made so electrophilic by enzymatic interactions (shown... 

The reactivity of enols was shown by Kresge61 to be very low with little carbanion character. Therefore, upon breaking the carbon-carbon bond in the decarboxylation of these acids, the adjacent leaving group possesses minimal carbanion character and will not be subject to significant carboxylation by carbon dioxide. Alternatively, if decarboxylation leads to the enolate, which has carbanion character, the internal return of C02 would become a competing factor. 

Salt formation can be used to identify and purify acids. Carboxylic acids are depro-tonated by the weak base sodium bicarbonate, forming the sodium salt of the acid, carbon dioxide, and water. An unknown compound that is insoluble in water, but dissolves in a sodium bicarbonate solution with a release of bubbles of carbon dioxide, is almost certainly a carboxylic acid. 

In an earlier investigation by the author (1), the product of Step 6 was isolated and converted into the carboxylic acid by reacting with magnesium then carboxylating with carbon dioxide. 

In short, the aminobutyric chain of I is oxidized to the level of an ester and the terminal carboxylic acid carbon to the level of carbon dioxide. This implies a grand total of three oxidative operations (not two), two on account of 2 mol of quinone, and one because of the C-COOH bond disconnection. 

A number of cases are known of ring contraction of tropolones to phenols, with extrusion of the carbonyl group as carboxylate or carbon dioxide. Examples are the conversions of the benzotropolone (216) to the naphthol ester (217 73%) with methanolic potash the pyridinotropolone (218) to the quinoline (219 50%) in dilute alkali the aminotropolone (220) to the methylsalicyclic acid (221 82%) on diazotization and the tropolonecarboxylate (222) to the dicarboxylic acid (223 78%) on brief alkali fu-... 

To our knowledge, only one report exists in which the formation of carboxylic acid by radical carboxylation with carbon dioxide has been documented. Curran and co-workers observed the formation of 9-anthracenecarboxylic acid in 10% yield, together with 71% yield of anthracene, when the radical reduction of 9-io-doanthracene with the ethylene-spaced fluorous tin hydride was run using supercritical CO2 (90°C, 280 atm) as the reaction media (Scheme 4-41) [69], As demonstrated in this example, the CO2 trapping reaction by radicals is not an efficient process and therefore is of limited synthetic utility. The rate constant for the addition is yet to be determined, but kinetic studies to date indicate that generally the decarboxylation of acyloxyl radicals is a rapid process [70]. 

Richter and Vogel oxidized cyclohexane in supercritical water for a varying reaction time from 5 to 80 sec range. The partial oxidation resulted in the desired cyclohexanone product, but the yield was very low (Fig. 7). The by-products included carboxylic acids, carbon monoxide, and carbon dioxide. 

Currently, carbon dioxide is used as a chemical feedstock for the production of carboxylic acids, carbonates, carbon monoxide, and urea (14—16). Despite the fact that numerous chemical reactions utilizing carbon dioxide are thermodynamically advantageous, there is often a substantial kinetic barrier to their occurrence. Transition metal compounds can serve to catalyze reactions of carbon dioxide, i.e., in the utilization of carbon dioxide in synthetic organic chemistry, transition metal complexes can simultaneously activate both carbon dioxide and other substrate molecules such as hydrogen or olefins. 

For carboxylations with carbon dioxide reversed-order addition is generally carried out, i.e. the solution or suspension of the metallated compound is poured on the powdered dry ice , which may be covered with an organic solvent. The reason for applying this technique is that alkali salts of carboxylic acids can undergo an attack by the organometallic derivative ... 

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